Android 开发笔记___实战项目：购物车

　　购物车的应用很广泛，电商app基本上都有它的身影。由于它用到了多种存储方式，通过项目对数据的存储有更高层次的了解。

1.设计思路

　　首先看看购物车的外观。第一次进入时里面是空的，去购物页面加入购物车以后，返回到购物车才能看到商品列表。

• • • 商品图表
    • 名称
    • 数量
    • 单价
    • 总价

　　一般购物车图标出现在几乎所有的页面，或者某一个角落。

　　一旦有新的商品加入购物车，购物车图标上的商品数量就加一。

　　任何页面点击购物车图标直接进入购物车页面

　　

　　用到的存储方式：

• • 数据库SQLite：是最直观的数据库，购物车里的商品列表一定放在SQLite中，增删改查都少不了它。
  • 共享参数sharedpreferences：不同页面上的购物车图标都有数字，表示商品数量。因为每个页面都要显示，如果用sqlite每次都要查询的话，就会很费资源。又因为商品数量需要持久存储，所以也不合适放在全局内存，不然下次启动就会清空。
  • SD卡文件：通常电商app的图标都来自服务器端，又因为图片下载很耗流量，因此一次加载后面从SD卡中读取之前加载的内容，加载又快又不耗流量，一举两得。
  • 全局内存：上面说了，访问SD卡果然是个好主意，然而商品频道、购物车频道等可能在一个页面显示多张商品小图，如果每张小图都访问依次SD卡，频繁的SD卡访问读写是很耗资源的。更好的办法是把商品小图加载进全局内存，这样直接从内存中获取图片，高效又快速。之所以不把商品大图放入全局内存，是因为大图很耗空间，一不小心就会占用几十兆内存。

2.小知识

　　菜单Menu

　　　　1. 选项菜单------optionMenu

　　　　　　　　通过按菜单键或点击事件触发

　　　　　　2.上下文菜单----contextMenu

　　　　　　　　通过长按事件触发

　　　　都有对应的菜单布局文件，放在res/menu目录下。

　　

　　1.选项菜单------optionMenu

　　　　弹出选项菜单的途径有3种：

　　　　　　（1）按菜单键

　　　　　　（2）在代码中手动打开，即调用openOptionMenu方法

　　　　　　（3）按工具栏右侧的溢出菜单按钮

　　　    需要重写两种方法：

• • • onCreateOptionMenu：在页面打开时调用，需要指定菜单列表的XML文件。
    • onOptionItemSelected：在列表的菜单项被选中时调用，需要对不同的菜单项做分支处理

  • <menu xmlns:android="http://schemas.android.com/apk/res/android" >
    
        <item
            android:id="@+id/menu_change_time"
            android:orderInCategory="1"
            android:title="改变时间"/>
    
        <item
            android:id="@+id/menu_change_color"
            android:orderInCategory="8"
            android:title="改变颜色"/>
        
        <item
            android:id="@+id/menu_change_bg"
            android:orderInCategory="9"
            android:title="改变背景"/>
        
    </menu>

    

  • <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:focusable="true"
        android:focusableInTouchMode="true"
        android:orientation="vertical"
        android:padding="10dp" >
    
        <Button
            android:id="@+id/btn_option"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="打开选项菜单，也可直接按菜单键"
            android:textColor="@color/black"
            android:textSize="17sp" />
        
        <TextView
            android:id="@+id/tv_option"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:gravity="left|center"
            android:textColor="@color/black"
            android:textSize="17sp" />
    
    </LinearLayout>

    package com.example.alimjan.hello_world;
    
    /**
     * Created by alimjan on 7/13/2017.
     */
    
            import com.example.alimjan.hello_world.Utils.DateUtil;
            import android.app.Activity;
            import android.content.Context;
            import android.content.Intent;
            import android.graphics.Color;
            import android.os.Bundle;
            import android.support.v7.app.AppCompatActivity;
            import android.util.Log;
            import android.view.Menu;
            import android.view.MenuItem;
            import android.view.View;
            import android.view.View.OnClickListener;
            import android.widget.TextView;
    
    public class class_4_5_2_1 extends Activity implements OnClickListener {
    
        private static final String TAG = "MenuOptionActivity";
        private TextView tv_option;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.code_4_5_2_1);
            tv_option = (TextView) findViewById(R.id.tv_option);
            findViewById(R.id.btn_option).setOnClickListener(this);
    
            setRandomTime();
        }
    
        @Override
        public void onClick(View v) {
            if (v.getId() == R.id.btn_option) {
                //注意：如果当前页面继承自AppCompatActivity，并且appcompat版本不低于22.1.0
                //那么调用openOptionsMenu方法将不会弹出菜单。这应该是Android的一个bug
                openOptionsMenu();
            }
        }
    
        @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            getMenuInflater().inflate(R.menu.menu_option, menu);
            return true;
        }
    
        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            int id = item.getItemId();
            if (id == R.id.menu_change_time) {
                setRandomTime();
            } else if (id == R.id.menu_change_color) {
                tv_option.setTextColor(getRandomColor());
            } else if (id == R.id.menu_change_bg) {
                tv_option.setBackgroundColor(getRandomColor());
            }
            return true;
        }
    
        private void setRandomTime() {
            String desc = DateUtil.getCurDateStr("yyyy-MM-dd HH:mm:ss") + " 这里是菜单显示文本";
            tv_option.setText(desc);
        }
    
        private int[] mColorArray = {
                Color.BLACK, Color.WHITE, Color.RED, Color.YELLOW, Color.GREEN,
                Color.BLUE, Color.CYAN, Color.MAGENTA, Color.GRAY, Color.DKGRAY
        };
        private int getRandomColor() {
            int random = (int) (Math.random()*10 % 10);
            return mColorArray[random];
        }
        public static void startHome(Context mContext) {
            Intent intent = new Intent(mContext, class_4_5_2_1.class);
            mContext.startActivity(intent);
        }
    
    }

　　2.上下文菜单----ContextMenu

　　　　弹出上下文菜单的途径有两种：

　　　　　　（1）默认在某个控件长按时弹出。

　　　　　　　　　通常在onStart方法中加入registerForContextMenu方法为指定控件注册上下文菜单，在onStop函数中加入unregisterForContextMenu方法为指定控件注销上下文　　　　　　　　　　                        　　菜单

　　　　　　（2）在长按事件之外的其他时间中打开上下文菜单，先执行registerForContextMenu方法注册菜单，然后执行openContextMenu方法打开菜单，最后执行　　　　　　　　                              unregisterForContextMenu方法注销菜单。

　　　　需要重写以下两种方法：

• • • onCreateContextMenu：在此指定菜单列表的XML文件，作为上下文菜单列表项的来源。
    • onContextItemSelected：在此对不同的菜单项做分支处理。

  • <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:focusable="true"
        android:focusableInTouchMode="true"
        android:orientation="vertical"
        android:padding="10dp" >
    
        <Button
            android:id="@+id/btn_context"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="打开上下文菜单，长按下面文本亦可"
            android:textColor="@color/black"
            android:textSize="17sp" />
    
        <TextView
            android:id="@+id/tv_context"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:gravity="left|center"
            android:textColor="@color/black"
            android:textSize="17sp" />
    
    </LinearLayout>

    package com.example.alimjan.hello_world;
    
    /**
     * Created by alimjan on 7/13/2017.
     */
            import com.example.alimjan.hello_world.Utils.DateUtil;
    
            import android.content.Context;
            import android.content.Intent;
            import android.graphics.Color;
            import android.os.Bundle;
            import android.support.v7.app.AppCompatActivity;
            import android.view.ContextMenu;
            import android.view.ContextMenu.ContextMenuInfo;
            import android.view.View.OnClickListener;
            import android.view.MenuItem;
            import android.view.View;
            import android.view.Window;
            import android.widget.TextView;
    
    public class class_4_5_2_2 extends AppCompatActivity implements OnClickListener {
    
        private TextView tv_context;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.code_4_5_2_2);
            tv_context = (TextView) findViewById(R.id.tv_context);
            findViewById(R.id.btn_context).setOnClickListener(this);
    
            setRandomTime();
        }
    
        @Override
        public void onClick(View v) {
            if (v.getId() == R.id.btn_context) {
                registerForContextMenu(v);
                openContextMenu(v);
                unregisterForContextMenu(v);
            }
        }
    
        @Override
        protected void onResume() {
            registerForContextMenu(tv_context);
            super.onResume();
        }
    
        @Override
        protected void onPause() {
            unregisterForContextMenu(tv_context);
            super.onPause();
        }
    
        @Override
        public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
            getMenuInflater().inflate(R.menu.menu_option, menu);
        }
    
        @Override
        public boolean onContextItemSelected(MenuItem item) {
            int id = item.getItemId();
            if (id == R.id.menu_change_time) {
                setRandomTime();
            } else if (id == R.id.menu_change_color) {
                tv_context.setTextColor(getRandomColor());
            } else if (id == R.id.menu_change_bg) {
                tv_context.setBackgroundColor(getRandomColor());
            }
            return true;
        }
    
        private void setRandomTime() {
            String desc = DateUtil.getCurDateStr("yyyy-MM-dd HH:mm:ss") + " 这里是菜单显示文本";
            tv_context.setText(desc);
        }
    
        private int[] mColorArray = {
                Color.BLACK, Color.WHITE, Color.RED, Color.YELLOW, Color.GREEN,
                Color.BLUE, Color.CYAN, Color.MAGENTA, Color.GRAY, Color.DKGRAY
        };
        private int getRandomColor() {
            int random = (int) (Math.random()*10 % 10);
            return mColorArray[random];
        }
        public static void startHome(Context mContext) {
            Intent intent = new Intent(mContext, class_4_5_2_2.class);
            mContext.startActivity(intent);
        }
    
    }

    上下文菜单的菜单列表固定显示在页面中部，菜单外的其他区域颜色会变深。

3.开始敲代码

　　步骤①　　想好代码文件与布局文件的名称。（这里因为放到自己的笔记本上，文件名按照序号来起。）

　　   步骤②　　在AndroidManiFest.xml文件中补充相应的配置。

　　   步骤③  　　敲业务逻辑以及布局文件的代码。

　　

　　下面贴代码：

shoppingcatractivity.java：

package com.example.alimjan.hello_world;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.util.TypedValue;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Gravity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.view.Window;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.example.alimjan.hello_world.Utils.FileUtil;
import com.example.alimjan.hello_world.bean.CartInfo;
import com.example.alimjan.hello_world.bean.GoodsInfo;
import com.example.alimjan.hello_world.dataBase.CartDBHelper;
import com.example.alimjan.hello_world.dataBase.GoodsDBHelper;
import com.example.alimjan.hello_world.Utils.DateUtil;
import com.example.alimjan.hello_world.Utils.SharedUtil;

import java.util.ArrayList;
import java.util.HashMap;

/**
 * Created by alimjan on 2017/07/13.
 */
public class ShoppingCartActivity extends Activity implements OnClickListener {

    private final static String TAG = "ShoppingCartActivity";
    private ImageView iv_menu;
    private TextView tv_title;
    private TextView tv_count;
    private TextView tv_total_price;
    private LinearLayout ll_content;
    private LinearLayout ll_cart;
    private LinearLayout ll_empty;
    private int mCount;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_shopping_cart);
        iv_menu = (ImageView) findViewById(R.id.iv_menu);
        tv_title = (TextView) findViewById(R.id.tv_title);
        tv_count = (TextView) findViewById(R.id.tv_count);
        tv_total_price = (TextView) findViewById(R.id.tv_total_price);
        ll_content = (LinearLayout) findViewById(R.id.ll_content);
        ll_cart = (LinearLayout) findViewById(R.id.ll_cart);
        ll_empty = (LinearLayout) findViewById(R.id.ll_empty);
        
        iv_menu.setOnClickListener(this);
        findViewById(R.id.btn_shopping_channel).setOnClickListener(this);
        findViewById(R.id.btn_settle).setOnClickListener(this);
        iv_menu.setVisibility(View.VISIBLE);
        tv_title.setText("购物车");
    }
    
    //显示购物车图标中的商品数量
    private void showCount(int count) {
        mCount = count;
        tv_count.setText(""+mCount);
        if (mCount == 0) {
            ll_content.setVisibility(View.GONE);
            ll_cart.removeAllViews();
            ll_empty.setVisibility(View.VISIBLE);
        } else {
            ll_content.setVisibility(View.VISIBLE);
            ll_empty.setVisibility(View.GONE);
        }
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.iv_menu) {
            openOptionsMenu();
        } else if (v.getId() == R.id.btn_shopping_channel) {
            Intent intent = new Intent(this, ShoppingChannelActivity.class);
            startActivity(intent);
        } else if (v.getId() == R.id.btn_settle) {
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.setTitle("结算商品");
            builder.setMessage("客官抱歉，支付功能尚未开通，请下次再来");
            builder.setPositiveButton("我知道了", null);
            builder.create().show();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_cart, menu);
        return true;
    }
    
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == R.id.menu_shopping) {
            Intent intent = new Intent(this, ShoppingChannelActivity.class);
            startActivity(intent);
        } else if (id == R.id.menu_clear) {
            //清空购物车数据库
            mCartHelper.deleteAll();
            ll_cart.removeAllViews();
            SharedUtil.getIntance(this).writeShared("count", "0");
            showCount(0);
            mCartGoods.clear();
            mGoodsMap.clear();
            Toast.makeText(this, "购物车已清空", Toast.LENGTH_SHORT).show();
        } else if (id == R.id.menu_return) {
            finish();
        }
        return true;
    }

    private HashMap<Integer, CartInfo> mCartGoods = new HashMap<Integer, CartInfo>();
    private View mContextView;
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
        mContextView = v;
        getMenuInflater().inflate(R.menu.menu_goods, menu);
    }

    @Override
    public boolean onContextItemSelected(MenuItem item) {
        CartInfo info = mCartGoods.get(mContextView.getId());
        int id = item.getItemId();
        if (id == R.id.menu_detail) {
            //跳转到查看商品详情页面
            goDetail(info.goods_id);
        } else if (id == R.id.menu_delete) {
            //从购物车删除商品的数据库操作
            long goods_id = info.goods_id;
            mCartHelper.delete("goods_id="+goods_id);
            ll_cart.removeView(mContextView);
            //更新购物车中的商品数量
            int left_count = mCount-info.count;
            for (int i=0; i<mCartArray.size(); i++) {
                if (goods_id == mCartArray.get(i).goods_id) {
                    left_count = mCount-mCartArray.get(i).count;
                    mCartArray.remove(i);
                    break;
                }
            }
            SharedUtil.getIntance(this).writeShared("count", ""+left_count);
            showCount(left_count);
            Toast.makeText(this, "已从购物车删除"+mGoodsMap.get(goods_id).name, Toast.LENGTH_SHORT).show();
            mGoodsMap.remove(goods_id);
            refreshTotalPrice();
        }
        return true;
    }
    
    private void goDetail(long rowid) {
        Intent intent = new Intent(this, ShoppingDetailActivity.class);
        intent.putExtra("goods_id", rowid);
        startActivity(intent);
    }

    private GoodsDBHelper mGoodsHelper;
    private CartDBHelper mCartHelper;
    private String mFirst = "true";
    
    @Override
    protected void onResume() {
        super.onResume();
        mCount = Integer.parseInt(SharedUtil.getIntance(this).readShared("count", "0"));
        showCount(mCount);
        mGoodsHelper = GoodsDBHelper.getInstance(this, 1);
        mGoodsHelper.openWriteLink();
        mCartHelper = CartDBHelper.getInstance(this, 1);
        mCartHelper.openWriteLink();
        mFirst = SharedUtil.getIntance(this).readShared("first", "true");
        downloadGoods();
        SharedUtil.getIntance(this).writeShared("first", "false");
        showCart();
    }
    
    @Override
    protected void onPause() {
        super.onPause();
        mGoodsHelper.closeLink();
        mCartHelper.closeLink();
    }

    private int mBeginViewId = 0x7F24FFF0;
    private ArrayList<CartInfo> mCartArray = new ArrayList<CartInfo>();
    private HashMap<Long, GoodsInfo> mGoodsMap = new HashMap<Long, GoodsInfo>();
    private void showCart() {
        mCartArray = mCartHelper.query("1=1");
        Log.d(TAG, "mCartArray.size()="+mCartArray.size());
        if (mCartArray==null || mCartArray.size()<=0) {
            return;
        }
        ll_cart.removeAllViews();
        LinearLayout ll_row = newLinearLayout(LinearLayout.HORIZONTAL, LayoutParams.WRAP_CONTENT);
        ll_row.addView(newTextView(0, 2, Gravity.CENTER, "图片", Color.BLACK, 15));
        ll_row.addView(newTextView(0, 3, Gravity.CENTER, "名称", Color.BLACK, 15));
        ll_row.addView(newTextView(0, 1, Gravity.CENTER, "数量", Color.BLACK, 15));
        ll_row.addView(newTextView(0, 1, Gravity.CENTER, "单价", Color.BLACK, 15));
        ll_row.addView(newTextView(0, 1, Gravity.CENTER, "总价", Color.BLACK, 15));
        ll_cart.addView(ll_row);
        for (int i=0; i<mCartArray.size(); i++) {
            final CartInfo info = mCartArray.get(i);
            GoodsInfo goods = mGoodsHelper.queryById(info.goods_id);
            Log.d(TAG, "name="+goods.name+",price="+goods.price+",desc="+goods.desc);
            mGoodsMap.put(info.goods_id, goods);
            ll_row = newLinearLayout(LinearLayout.HORIZONTAL, LayoutParams.WRAP_CONTENT);
            ll_row.setId(mBeginViewId+i);
            //添加商品小图
            ImageView iv_thumb = new ImageView(this);
            LinearLayout.LayoutParams iv_params = new LinearLayout.LayoutParams(
                    0, LayoutParams.WRAP_CONTENT, 2);
            iv_thumb.setLayoutParams(iv_params);
            iv_thumb.setScaleType(ScaleType.FIT_CENTER);
            iv_thumb.setImageBitmap(MainApplication.getInstance().mIconMap.get(info.goods_id));
            ll_row.addView(iv_thumb);
            //添加商品名称与描述
            LinearLayout ll_name = new LinearLayout(this);
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
                    0, LayoutParams.MATCH_PARENT, 3);
            ll_name.setLayoutParams(params);
            ll_name.setOrientation(LinearLayout.VERTICAL);
            ll_name.addView(newTextView(-3, 1, Gravity.LEFT, goods.name, Color.BLACK, 17));
            ll_name.addView(newTextView(-3, 1, Gravity.LEFT, goods.desc, Color.GRAY, 12));
            ll_row.addView(ll_name);
            //添加商品数量、单价和总价
            ll_row.addView(newTextView(1, 1, Gravity.CENTER, ""+info.count, Color.BLACK, 17));
            ll_row.addView(newTextView(1, 1, Gravity.RIGHT, ""+(int)goods.price, Color.BLACK, 15));
            ll_row.addView(newTextView(1, 1, Gravity.RIGHT, ""+(int)(info.count*goods.price), Color.RED, 17));
            //给商品行添加点击事件
            ll_row.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                    goDetail(info.goods_id);
                }
            });
            //给商品行注册上下文菜单
            unregisterForContextMenu(ll_row);
            registerForContextMenu(ll_row);
            mCartGoods.put(ll_row.getId(), info);
            ll_cart.addView(ll_row);
        }
        refreshTotalPrice();
    }
    
    private void refreshTotalPrice() {
        int total_price = 0;
        for (CartInfo info : mCartArray) {
            GoodsInfo goods = mGoodsMap.get(info.goods_id);
            total_price += goods.price*info.count;
        }
        tv_total_price.setText(""+total_price);
    }
    
    private LinearLayout newLinearLayout(int orientation, int height) {
        LinearLayout ll_new = new LinearLayout(this);
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
                LayoutParams.MATCH_PARENT, height);
        //params.setMargins(2, 2, 2, 2);
        ll_new.setLayoutParams(params);
        ll_new.setOrientation(orientation);
        ll_new.setBackgroundColor(Color.WHITE);
        return ll_new;
    }

    private TextView newTextView(int height, float weight, int gravity, String text, int textColor, int textSize) {
        TextView tv_new = new TextView(this);
        if (height == -3) {  //垂直排列
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
                    LayoutParams.MATCH_PARENT, 0, weight);
            tv_new.setLayoutParams(params);
        } else {  //水平排列
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
                    0, (height==0)?LayoutParams.WRAP_CONTENT:LayoutParams.MATCH_PARENT, weight);
            tv_new.setLayoutParams(params);
        }
        tv_new.setText(text);
        tv_new.setTextColor(textColor);
        tv_new.setTextSize(TypedValue.COMPLEX_UNIT_SP, textSize);
        tv_new.setGravity(Gravity.CENTER|gravity);
        return tv_new;
    }

    private String[] mNameArray = {
            "iphone7", "Mate8", "小米5", "vivo X6S", "OPPO R9plus", "魅族Pro6"
            };
    private String[] mDescArray = {
            "Apple iPhone 7 128GB 玫瑰金色 移动联通电信4G手机",
            "华为 HUAWEI Mate8 3GB+32GB版 移动联通4G手机（月光银）",
            "小米手机5 全网通 高配版 3GB内存 64GB 白色",
            "vivo X6S 金色 全网通4G 双卡双待 4GB+64GB",
            "OPPO R9plus 4GB+64GB内存版 金色 全网通4G手机 双卡双待",
            "魅族Pro6全网通公开版 4+32GB 银白色 移动联通电信4G手机 双卡双待"
            };
    private float[] mPriceArray = {5888, 2499, 1799, 2298, 2499, 2199};
    private int[] mThumbArray = {
            R.drawable.iphone_s, R.drawable.huawei_s, R.drawable.xiaomi_s,
            R.drawable.vivo_s, R.drawable.oppo_9p_s, R.drawable.meizu_s
            };
    private int[] mPicArray = {
            R.drawable.iphone, R.drawable.huawei, R.drawable.xiaomi,
            R.drawable.vivo, R.drawable.oppo_9p, R.drawable.meizu
            };
    //模拟网络数据，初始化数据库中的商品信息
    private void downloadGoods() {
        String path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/";
        if (mFirst.equals("true")) {
            for (int i=0; i<mNameArray.length; i++) {
                GoodsInfo info = new GoodsInfo();
                info.name = mNameArray[i];
                info.desc = mDescArray[i];
                info.price = mPriceArray[i];
                long rowid = mGoodsHelper.insert(info);
                info.rowid = rowid;
                //往全局内存写入商品小图
                Bitmap thumb = BitmapFactory.decodeResource(getResources(), mThumbArray[i]);
                MainApplication.getInstance().mIconMap.put(rowid, thumb);
                String thumb_path = path + rowid + "_s.jpg";
                FileUtil.saveImage(thumb_path, thumb);
                info.thumb_path = thumb_path;
                //往SD卡保存商品大图
                Bitmap pic = BitmapFactory.decodeResource(getResources(), mPicArray[i]);
                String pic_path = path + rowid + ".jpg";
                FileUtil.saveImage(pic_path, pic);
                pic.recycle();
                info.pic_path = pic_path;
                mGoodsHelper.update(info);
            }
        } else {
            ArrayList<GoodsInfo> goodsArray = mGoodsHelper.query("1=1");
            for (int i=0; i<goodsArray.size(); i++) {
                GoodsInfo info = goodsArray.get(i);
                Bitmap thumb = BitmapFactory.decodeFile(info.thumb_path);
                MainApplication.getInstance().mIconMap.put(info.rowid, thumb);
            }
        }
    }

    public static void startHome(Context mContext) {
        Intent intent = new Intent(mContext, ShoppingCartActivity.class);
        mContext.startActivity(intent);
    }

}

ShoppingChannelActivity:

package com.example.alimjan.hello_world;

import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;
import android.widget.TextView;
import android.widget.Toast;

import com.example.alimjan.hello_world.bean.CartInfo;
import com.example.alimjan.hello_world.bean.GoodsInfo;
import com.example.alimjan.hello_world.dataBase.CartDBHelper;
import com.example.alimjan.hello_world.dataBase.GoodsDBHelper;
import com.example.alimjan.hello_world.Utils.DateUtil;
import com.example.alimjan.hello_world.Utils.SharedUtil;

import java.util.ArrayList;

/**
 * Created by alimjan on 2017/07/13.
 */
public class ShoppingChannelActivity extends AppCompatActivity implements OnClickListener {

    private final static String TAG = "ShoppingChannelActivity";
    private TextView tv_title;
    private TextView tv_count;
    private LinearLayout ll_channel;
    private int mCount;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_shopping_channel);
        tv_title = (TextView) findViewById(R.id.tv_title);
        tv_count = (TextView) findViewById(R.id.tv_count);
        ll_channel = (LinearLayout) findViewById(R.id.ll_channel);
        findViewById(R.id.iv_cart).setOnClickListener(this);
        tv_title.setText("手机商场");
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.iv_cart) {
            Intent intent = new Intent(this, ShoppingCartActivity.class);
            startActivity(intent);
        }
    }

    private void addToCart(long goods_id) {
        mCount++;
        tv_count.setText(""+mCount);
        SharedUtil.getIntance(this).writeShared("count", ""+mCount);
        CartInfo info = mCartHelper.queryByGoodsId(goods_id);
        if (info != null) {
            info.count++;
            info.update_time = DateUtil.getCurDateStr("");
            mCartHelper.update(info);
        } else {
            info = new CartInfo();
            info.goods_id = goods_id;
            info.count = 1;
            info.update_time = DateUtil.getCurDateStr("");
            mCartHelper.insert(info);
        }
    }

    private GoodsDBHelper mGoodsHelper;
    private CartDBHelper mCartHelper;
    
    @Override
    protected void onResume() {
        super.onResume();
        mCount = Integer.parseInt(SharedUtil.getIntance(this).readShared("count", "0"));
        tv_count.setText(""+mCount);
        mGoodsHelper = GoodsDBHelper.getInstance(this, 1);
        mGoodsHelper.openReadLink();
        mCartHelper = CartDBHelper.getInstance(this, 1);
        mCartHelper.openWriteLink();
        //展示商品列表
        showGoods();
    }
    
    @Override
    protected void onPause() {
        super.onPause();
        mGoodsHelper.closeLink();
        mCartHelper.closeLink();
    }

    private LayoutParams mFullParams, mHalfParams;
    private void showGoods() {
        ll_channel.removeAllViews();
        mFullParams = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        mHalfParams = new LayoutParams(0, LayoutParams.WRAP_CONTENT, 1);
        mHalfParams.setMargins(2, 2, 2, 2);
        LinearLayout ll_row = newLinearLayout(LinearLayout.HORIZONTAL, 0);
        ArrayList<GoodsInfo> goodsArray = mGoodsHelper.query("1=1");
        int i=0;
        for (; i<goodsArray.size(); i++) {
            final GoodsInfo info = goodsArray.get(i);
            LinearLayout ll_goods = newLinearLayout(LinearLayout.VERTICAL, 1);
            ll_goods.setBackgroundColor(Color.WHITE);
            //添加商品标题
            TextView tv_name = new TextView(this);
            tv_name.setLayoutParams(mFullParams);
            tv_name.setGravity(Gravity.CENTER);
            tv_name.setText(info.name);
            tv_name.setTextColor(Color.BLACK);
            tv_name.setTextSize(TypedValue.COMPLEX_UNIT_SP, 17);
            ll_goods.addView(tv_name);
            //添加商品小图
            ImageView iv_thumb = new ImageView(this);
            iv_thumb.setLayoutParams(new LayoutParams(
                    LayoutParams.MATCH_PARENT, 200));
            iv_thumb.setScaleType(ScaleType.FIT_CENTER);
            iv_thumb.setImageBitmap(MainApplication.getInstance().mIconMap.get(info.rowid));
            iv_thumb.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                    Intent intent = new Intent(ShoppingChannelActivity.this, ShoppingDetailActivity.class);
                    intent.putExtra("goods_id", info.rowid);
                    startActivity(intent);
                }
            });
            ll_goods.addView(iv_thumb);
            //添加商品价格
            LinearLayout ll_bottom = newLinearLayout(LinearLayout.HORIZONTAL, 0);
            TextView tv_price = new TextView(this);
            tv_price.setLayoutParams(new LayoutParams(0, LayoutParams.WRAP_CONTENT, 2));
            tv_price.setGravity(Gravity.CENTER);
            tv_price.setText(""+(int)info.price);
            tv_price.setTextColor(Color.RED);
            tv_price.setTextSize(TypedValue.COMPLEX_UNIT_SP, 15);
            ll_bottom.addView(tv_price);
            //添加购物车按钮
            Button btn_add = new Button(this);
            btn_add.setLayoutParams(new LayoutParams(0, LayoutParams.WRAP_CONTENT, 3));
            btn_add.setGravity(Gravity.CENTER);
            btn_add.setText("加入购物车");
            btn_add.setTextColor(Color.BLACK);
            btn_add.setTextSize(TypedValue.COMPLEX_UNIT_SP, 15);
            btn_add.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                    addToCart(info.rowid);
                    Toast.makeText(ShoppingChannelActivity.this, 
                            "已添加一部"+info.name+"到购物车", Toast.LENGTH_SHORT).show();
                }
            });
            ll_bottom.addView(btn_add);
            ll_goods.addView(ll_bottom);
            //添加商品项目
            ll_row.addView(ll_goods);
            if (i%2 == 1) {
                ll_channel.addView(ll_row);
                ll_row = newLinearLayout(LinearLayout.HORIZONTAL, 0);
            }
        }
        if (i%2 == 0) {
            ll_row.addView(newLinearLayout(LinearLayout.VERTICAL, 1));
            ll_channel.addView(ll_row);
        }
    }

    private LinearLayout newLinearLayout(int orientation, int weight) {
        LinearLayout ll_new = new LinearLayout(this);
        ll_new.setLayoutParams((weight==0)?mFullParams:mHalfParams);
        ll_new.setOrientation(orientation);
        return ll_new;
    }

}

ShoppingDetailActivity:

package com.example.alimjan.hello_world;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;


import com.example.alimjan.hello_world.bean.CartInfo;
import com.example.alimjan.hello_world.bean.GoodsInfo;
import com.example.alimjan.hello_world.dataBase.CartDBHelper;
import com.example.alimjan.hello_world.dataBase.GoodsDBHelper;
import com.example.alimjan.hello_world.Utils.DateUtil;
import com.example.alimjan.hello_world.Utils.SharedUtil;

/**
 * Created by alimjan on 2017/07/13.
 */
public class ShoppingDetailActivity extends AppCompatActivity implements OnClickListener {

    private TextView tv_title;
    private TextView tv_count;
    private TextView tv_goods_price;
    private TextView tv_goods_desc;
    private ImageView iv_goods_pic;
    private int mCount;
    private long mGoodsId;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_shopping_detail);
        tv_title = (TextView) findViewById(R.id.tv_title);
        tv_count = (TextView) findViewById(R.id.tv_count);
        tv_goods_price = (TextView) findViewById(R.id.tv_goods_price);
        tv_goods_desc = (TextView) findViewById(R.id.tv_goods_desc);
        iv_goods_pic = (ImageView) findViewById(R.id.iv_goods_pic);
        findViewById(R.id.iv_cart).setOnClickListener(this);
        findViewById(R.id.btn_add_cart).setOnClickListener(this);
        
        mCount = Integer.parseInt(SharedUtil.getIntance(this).readShared("count", "0"));
        tv_count.setText(""+mCount);
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.iv_cart) {
            Intent intent = new Intent(this, ShoppingCartActivity.class);
            startActivity(intent);
        } else if (v.getId() == R.id.btn_add_cart) {
            //添加购物车数据库
            addToCart(mGoodsId);
            Toast.makeText(this, "成功添加至购物车", Toast.LENGTH_SHORT).show();
        }
    }
    
    private void addToCart(long goods_id) {
        mCount++;
        tv_count.setText(""+mCount);
        SharedUtil.getIntance(this).writeShared("count", ""+mCount);
        CartInfo info = mCartHelper.queryByGoodsId(goods_id);
        if (info != null) {
            info.count++;
            info.update_time = DateUtil.getCurDateStr("");
            mCartHelper.update(info);
        } else {
            info = new CartInfo();
            info.goods_id = goods_id;
            info.count = 1;
            info.update_time = DateUtil.getCurDateStr("");
            mCartHelper.insert(info);
        }
    }

    private GoodsDBHelper mGoodsHelper;
    private CartDBHelper mCartHelper;
    
    @Override
    protected void onResume() {
        super.onResume();
        mGoodsHelper = GoodsDBHelper.getInstance(this, 1);
        mGoodsHelper.openReadLink();
        mCartHelper = CartDBHelper.getInstance(this, 1);
        mCartHelper.openWriteLink();
        //展示商品信息
        showDetail();
    }
    
    @Override
    protected void onPause() {
        super.onPause();
        mGoodsHelper.closeLink();
        mCartHelper.closeLink();
    }
    
    private void showDetail() {
        mGoodsId = getIntent().getLongExtra("goods_id", 0l);
        if (mGoodsId > 0) {
            GoodsInfo info = mGoodsHelper.queryById(mGoodsId);
            tv_title.setText(info.name);
            tv_goods_desc.setText(info.desc);
            tv_goods_price.setText(""+info.price);
            Bitmap pic = BitmapFactory.decodeFile(info.pic_path);
            iv_goods_pic.setImageBitmap(pic);
        }
    }

}

activity_shopping_cart.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffdd"
    android:orientation="vertical" >

    <include layout="@layout/activity_shopping_title" />

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="5dp" >
            
            <LinearLayout
                android:id="@+id/ll_content"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical"
                android:visibility="gone" >

                <LinearLayout
                    android:id="@+id/ll_cart"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:orientation="vertical" >
                </LinearLayout>
                
                <LinearLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:orientation="horizontal"
                    android:padding="10dp" >

                    <TextView
                        android:layout_width="0dp"
                        android:layout_height="wrap_content"
                        android:layout_weight="1"
                        android:gravity="center|right"
                        android:text="总金额："
                        android:textColor="@color/black"
                        android:textSize="17sp" />

                    <TextView
                        android:id="@+id/tv_total_price"
                        android:layout_width="0dp"
                        android:layout_height="wrap_content"
                        android:layout_weight="2"
                        android:gravity="center|left"
                        android:textColor="@color/red"
                        android:textSize="25sp" />

                    <Button
                        android:id="@+id/btn_settle"
                        android:layout_width="0dp"
                        android:layout_height="wrap_content"
                        android:layout_weight="1"
                        android:gravity="center"
                        android:text="结算"
                        android:textColor="@color/black"
                        android:textSize="20sp" />
                </LinearLayout>

            </LinearLayout>

            <LinearLayout
                android:id="@+id/ll_empty"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical"
                android:visibility="gone" >

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginBottom="100dp"
                    android:layout_marginTop="100dp"
                    android:gravity="center"
                    android:text="哎呀，购物车空空如也，快去选购商品吧"
                    android:textColor="@color/black"
                    android:textSize="17sp" />

                <Button
                    android:id="@+id/btn_shopping_channel"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:text="逛逛手机商场"
                    android:textColor="@color/black"
                    android:textSize="17sp" />
            </LinearLayout>
        </FrameLayout>
    </ScrollView>

</LinearLayout>

activity_shopping_channel.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffdd"
    android:orientation="vertical" >

    <include layout="@layout/activity_shopping_title" />

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <LinearLayout
            android:id="@+id/ll_channel"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="5dp"
            android:orientation="vertical" >
        </LinearLayout>
    </ScrollView>

</LinearLayout>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffdd"
    android:orientation="vertical" >

    <include layout="@layout/activity_shopping_title" />

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="5dp"
            android:orientation="vertical" >

            <ImageView
                android:id="@+id/iv_goods_pic"
                android:layout_width="match_parent"
                android:layout_height="400dp"
                android:scaleType="fitCenter" />

            <TextView
                android:id="@+id/tv_goods_price"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textColor="@color/red"
                android:textSize="22sp" />

            <TextView
                android:id="@+id/tv_goods_desc"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textColor="@color/black"
                android:textSize="15sp" />

            <Button
                android:id="@+id/btn_add_cart"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="加入购物车"
                android:textColor="@color/black"
                android:textSize="17sp" />
        </LinearLayout>
    </ScrollView>

</LinearLayout>

　　一些工具类：

package com.example.alimjan.hello_world.Utils;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.Locale;

public class FileUtil {

    public static void saveText(String path, String txt) {
        try {
            FileOutputStream fos = new FileOutputStream(path);
            fos.write(txt.getBytes());
            fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static String openText(String path) {
        String readStr = "";
        try {
            FileInputStream fis = new FileInputStream(path);
            byte[] b = new byte[fis.available()];
            fis.read(b);
            readStr = new String(b);
            fis.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return readStr;
    }

    public static void saveImage(String path, Bitmap bitmap) {
        try {
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(path));
            bitmap.compress(Bitmap.CompressFormat.JPEG, 80, bos);
            bos.flush();
            bos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    public static Bitmap openImage(String path) {
        Bitmap bitmap = null;
        try {
            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(path));
            bitmap = BitmapFactory.decodeStream(bis);
            bis.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return bitmap;
    }
    
    public static ArrayList<File> getFileList(String path, String[] extendArray) {
        ArrayList<File> displayedContent = new ArrayList<File>();
        File[] files = null;
        File directory = new File(path);
        if (extendArray != null && extendArray.length>0) {
            FilenameFilter fileFilter = getTypeFilter(extendArray);
            files = directory.listFiles(fileFilter);
        } else {
            files = directory.listFiles();
        }

        if (files != null) {
            for (File f : files) {
                if (!f.isDirectory() && !f.isHidden()) {
                    displayedContent.add(f);
                }
            }
        }
        return displayedContent;
    }

    public static FilenameFilter getTypeFilter(String[] extendArray) {
        final ArrayList<String> fileExtensions = new ArrayList<String>();
        for (int i=0; i<extendArray.length; i++) {
            fileExtensions.add(extendArray[i]);
        }
        FilenameFilter fileNameFilter = new FilenameFilter() {
            @Override
            public boolean accept(File directory, String fileName) {
                boolean matched = false;
                File f = new File(String.format("%s/%s",
                        directory.getAbsolutePath(), fileName));
                matched = f.isDirectory();
                if (!matched) {
                    for (String s : fileExtensions) {
                        s = String.format(".{0,}\%s$", s);
                        s = s.toUpperCase(Locale.getDefault());
                        fileName = fileName.toUpperCase(Locale.getDefault());
                        matched = fileName.matches(s);
                        if (matched) {
                            break;
                        }
                    }
                }
                return matched;
            }
        };
        return fileNameFilter;
    }

}

package com.example.alimjan.hello_world.dataBase;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

import com.example.alimjan.hello_world.bean.GoodsInfo;

import java.util.ArrayList;

public class GoodsDBHelper extends SQLiteOpenHelper {
    private static final String TAG = "GoodsDBHelper";
    private static final String DB_NAME = "goods.db";
    private static final int DB_VERSION = 1;
    private static GoodsDBHelper mHelper = null;
    private SQLiteDatabase mDB = null;
    private static final String TABLE_NAME = "goods_info";

    private GoodsDBHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }

    private GoodsDBHelper(Context context, int version) {
        super(context, DB_NAME, null, version);
    }

    public static GoodsDBHelper getInstance(Context context, int version) {
        if (version > 0 && mHelper == null) {
            mHelper = new GoodsDBHelper(context, version);
        } else if (mHelper == null) {
            mHelper = new GoodsDBHelper(context);
        }
        return mHelper;
    }

    public SQLiteDatabase openReadLink() {
        if (mDB == null || mDB.isOpen() != true) {
            mDB = mHelper.getReadableDatabase();
        }
        return mDB;
    }

    public SQLiteDatabase openWriteLink() {
        if (mDB == null || mDB.isOpen() != true) {
            mDB = mHelper.getWritableDatabase();
        }
        return mDB;
    }

    public void closeLink() {
        if (mDB != null && mDB.isOpen() == true) {
            mDB.close();
            mDB = null;
        }
    }
    
    public String getDBName() {
        if (mHelper != null) {
            return mHelper.getDatabaseName();
        } else {
            return DB_NAME;
        }
    }
    
    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.d(TAG, "onCreate");
        String drop_sql = "DROP TABLE IF EXISTS " + TABLE_NAME + ";";
        Log.d(TAG, "drop_sql:" + drop_sql);
        db.execSQL(drop_sql);
        String create_sql = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME + " ("
                + "_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,"
                + "name VARCHAR NOT NULL," + "desc VARCHAR NOT NULL,"
                + "price FLOAT NOT NULL," + "thumb_path VARCHAR NOT NULL,"
                + "pic_path VARCHAR NOT NULL"
                + ");";
        Log.d(TAG, "create_sql:" + create_sql);
        db.execSQL(create_sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }
    
    public int delete(String condition) {
        int count = mDB.delete(TABLE_NAME, condition, null);
        return count;
    }

    public int deleteAll() {
        int count = mDB.delete(TABLE_NAME, "1=1", null);
        return count;
    }

    public long insert(GoodsInfo info) {
        ArrayList<GoodsInfo> infoArray = new ArrayList<GoodsInfo>();
        infoArray.add(info);
        return insert(infoArray);
    }
    
    public long insert(ArrayList<GoodsInfo> infoArray) {
        long result = -1;
        for (int i = 0; i < infoArray.size(); i++) {
            GoodsInfo info = infoArray.get(i);
            // 如果存在相同rowid的记录，则更新记录
            if (info.rowid > 0) {
                String condition = String.format("rowid='%d'", info.rowid);
                update(info, condition);
                result = info.rowid;
                continue;
            }
            // 不存在唯一性重复的记录，则插入新记录
            ContentValues cv = new ContentValues();
            cv.put("name", info.name);
            cv.put("desc", info.desc);
            cv.put("price", info.price);
            cv.put("thumb_path", info.thumb_path);
            cv.put("pic_path", info.pic_path);
            result = mDB.insert(TABLE_NAME, "", cv);
            // 添加成功后返回行号，失败后返回-1
            if (result == -1) {
                return result;
            }
        }
        return result;
    }

    public int update(GoodsInfo info, String condition) {
        ContentValues cv = new ContentValues();
        cv.put("name", info.name);
        cv.put("desc", info.desc);
        cv.put("price", info.price);
        cv.put("thumb_path", info.thumb_path);
        cv.put("pic_path", info.pic_path);
        int count = mDB.update(TABLE_NAME, cv, condition, null);
        return count;
    }

    public int update(GoodsInfo info) {
        return update(info, "rowid="+info.rowid);
    }

    public ArrayList<GoodsInfo> query(String condition) {
        String sql = String.format("select rowid,_id,name,desc,price,thumb_path,pic_path" +
                " from %s where %s;", TABLE_NAME, condition);
        Log.d(TAG, "query sql: "+sql);
        ArrayList<GoodsInfo> infoArray = new ArrayList<GoodsInfo>();
        Cursor cursor = mDB.rawQuery(sql, null);
        if (cursor.moveToFirst()) {
            for (;; cursor.moveToNext()) {
                GoodsInfo info = new GoodsInfo();
                info.rowid = cursor.getLong(0);
                info.xuhao = cursor.getInt(1);
                info.name = cursor.getString(2);
                info.desc = cursor.getString(3);
                info.price = cursor.getFloat(4);
                info.thumb_path = cursor.getString(5);
                info.pic_path = cursor.getString(6);
                infoArray.add(info);
                if (cursor.isLast() == true) {
                    break;
                }
            }
        }
        cursor.close();
        return infoArray;
    }
    
    public GoodsInfo queryById(long rowid) {
        GoodsInfo info = null;
        ArrayList<GoodsInfo> infoArray = query(String.format("rowid='%d'", rowid));
        if (infoArray.size() > 0) {
            info = infoArray.get(0);
        }
        return info;
    }

}

package com.example.alimjan.hello_world.dataBase;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

import com.example.alimjan.hello_world.bean.CartInfo;

import java.util.ArrayList;

public class CartDBHelper extends SQLiteOpenHelper {
    private static final String TAG = "CartDBHelper";
    private static final String DB_NAME = "cart.db";
    private static final int DB_VERSION = 1;
    private static CartDBHelper mHelper = null;
    private SQLiteDatabase mDB = null;
    private static final String TABLE_NAME = "cart_info";

    private CartDBHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }

    private CartDBHelper(Context context, int version) {
        super(context, DB_NAME, null, version);
    }

    public static CartDBHelper getInstance(Context context, int version) {
        if (version > 0 && mHelper == null) {
            mHelper = new CartDBHelper(context, version);
        } else if (mHelper == null) {
            mHelper = new CartDBHelper(context);
        }
        return mHelper;
    }

    public SQLiteDatabase openReadLink() {
        if (mDB == null || mDB.isOpen() != true) {
            mDB = mHelper.getReadableDatabase();
        }
        return mDB;
    }

    public SQLiteDatabase openWriteLink() {
        if (mDB == null || mDB.isOpen() != true) {
            mDB = mHelper.getWritableDatabase();
        }
        return mDB;
    }

    public void closeLink() {
        if (mDB != null && mDB.isOpen() == true) {
            mDB.close();
            mDB = null;
        }
    }
    
    public String getDBName() {
        if (mHelper != null) {
            return mHelper.getDatabaseName();
        } else {
            return DB_NAME;
        }
    }
    
    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.d(TAG, "onCreate");
        String drop_sql = "DROP TABLE IF EXISTS " + TABLE_NAME + ";";
        Log.d(TAG, "drop_sql:" + drop_sql);
        db.execSQL(drop_sql);
        String create_sql = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME + " ("
                + "_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,"
                + "goods_id LONG NOT NULL," + "count INTEGER NOT NULL,"
                + "update_time VARCHAR NOT NULL"
                + ");";
        Log.d(TAG, "create_sql:" + create_sql);
        db.execSQL(create_sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }
    
    public int delete(String condition) {
        int count = mDB.delete(TABLE_NAME, condition, null);
        return count;
    }

    public int deleteAll() {
        int count = mDB.delete(TABLE_NAME, "1=1", null);
        return count;
    }

    public long insert(CartInfo info) {
        ArrayList<CartInfo> infoArray = new ArrayList<CartInfo>();
        infoArray.add(info);
        return insert(infoArray);
    }
    
    public long insert(ArrayList<CartInfo> infoArray) {
        long result = -1;
        for (int i = 0; i < infoArray.size(); i++) {
            CartInfo info = infoArray.get(i);
            Log.d(TAG, "goods_id="+info.goods_id+", count="+info.count);
            // 如果存在相同rowid的记录，则更新记录
            if (info.rowid > 0) {
                String condition = String.format("rowid='%d'", info.rowid);
                update(info, condition);
                result = info.rowid;
                continue;
            }
            // 不存在唯一性重复的记录，则插入新记录
            ContentValues cv = new ContentValues();
            cv.put("goods_id", info.goods_id);
            cv.put("count", info.count);
            cv.put("update_time", info.update_time);
            result = mDB.insert(TABLE_NAME, "", cv);
            // 添加成功后返回行号，失败后返回-1
            if (result == -1) {
                return result;
            }
        }
        return result;
    }

    public int update(CartInfo info, String condition) {
        ContentValues cv = new ContentValues();
        cv.put("goods_id", info.goods_id);
        cv.put("count", info.count);
        cv.put("update_time", info.update_time);
        int count = mDB.update(TABLE_NAME, cv, condition, null);
        return count;
    }

    public int update(CartInfo info) {
        return update(info, "rowid="+info.rowid);
    }

    public ArrayList<CartInfo> query(String condition) {
        String sql = String.format("select rowid,_id,goods_id,count,update_time" +
                " from %s where %s;", TABLE_NAME, condition);
        Log.d(TAG, "query sql: "+sql);
        ArrayList<CartInfo> infoArray = new ArrayList<CartInfo>();
        Cursor cursor = mDB.rawQuery(sql, null);
        if (cursor.moveToFirst()) {
            for (;; cursor.moveToNext()) {
                CartInfo info = new CartInfo();
                info.rowid = cursor.getLong(0);
                info.xuhao = cursor.getInt(1);
                info.goods_id = cursor.getLong(2);
                info.count = cursor.getInt(3);
                info.update_time = cursor.getString(4);
                infoArray.add(info);
                if (cursor.isLast() == true) {
                    break;
                }
            }
        }
        cursor.close();
        return infoArray;
    }
    
    public CartInfo queryById(long rowid) {
        CartInfo info = null;
        ArrayList<CartInfo> infoArray = query(String.format("rowid='%d'", rowid));
        if (infoArray.size() > 0) {
            info = infoArray.get(0);
        }
        return info;
    }

    public CartInfo queryByGoodsId(long goods_id) {
        CartInfo info = null;
        ArrayList<CartInfo> infoArray = query(String.format("goods_id='%d'", goods_id));
        if (infoArray.size() > 0) {
            info = infoArray.get(0);
        }
        return info;
    }

}

package com.example.alimjan.hello_world.bean;

public class GoodsInfo {
    public long rowid;
    public int xuhao;
    public String name;
    public String desc;
    public float price;
    public String thumb_path;
    public String pic_path;
    
    public GoodsInfo() {
        rowid = 0l;
        xuhao = 0;
        name = "";
        desc = "";
        price = 0;
        thumb_path = "";
        pic_path = "";
    }
}

package com.example.alimjan.hello_world.bean;

public class CartInfo {
    public long rowid;
    public int xuhao;
    public long goods_id;
    public int count;
    public String update_time;
    
    public CartInfo() {
        rowid = 0l;
        xuhao = 0;
        goods_id = 0l;
        count = 0;
        update_time = "";
    }
}

<menu xmlns:android="http://schemas.android.com/apk/res/android" >

    <item
        android:id="@+id/menu_shopping"
        android:orderInCategory="1"
        android:title="去商场购物"/>

    <item
        android:id="@+id/menu_clear"
        android:orderInCategory="2"
        android:title="清空购物车"/>
    
    <item
        android:id="@+id/menu_return"
        android:orderInCategory="9"
        android:title="返回"/>
    
</menu>

<menu xmlns:android="http://schemas.android.com/apk/res/android" >

    <item
        android:id="@+id/menu_detail"
        android:orderInCategory="1"
        android:title="查看商品详情"/>

    <item
        android:id="@+id/menu_delete"
        android:orderInCategory="2"
        android:title="从购物车删除"/>
    
</menu>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval" >

    <solid android:color="#ff6666" />

</shape>

 

到此也就完成的差不多了，一些工具类放在下面了。