长按显示菜单选项，系统菜单，上下文菜单

今天看视频学了新的知识，那就是通过两种不同的方式实现菜单（java代码实现、xml文件实现）菜单。先来上几个程序运行截图：

这是三个小案例的截图，我就不废话那么多，直接上例子代码了。

案例一代码就是一个java代码。是通过java代码实现菜单的。

MainActivity.java

package cn.edu.aynu.rjxy.activity;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        //getMenuInflater().inflate(R.menu.main, menu);
        //使用java代码实现菜单，最多显示6个子菜单
        MenuItem menuItem = menu.add(1001, 100, 1, "系统菜单");
        menuItem.setTitle("菜单一");
        MenuItem menuItem2 = menu.add(1001, 101, 2, "用户菜单");
        menuItem2.setTitle("菜单二");
        MenuItem menuItem3 = menu.add(1001, 102, 2, "客户菜单");
        menuItem3.setTitle("菜单三");
        return true;
    }
    
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case 100:
            Toast.makeText(MainActivity.this, "选择了菜单一", 0).show();
            break;
        case 101:
            Toast.makeText(MainActivity.this, "选择了菜单二", 0).show();
            break;
        case 102:
            Toast.makeText(MainActivity.this, "选择了菜单三", 0).show();
            break;

        default:
            break;
        }
        return super.onOptionsItemSelected(item);
    }
    
}

案例二代码：

在下面你的截图中的xml文件中写下面的代码：

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

    <item
        android:id="@+id/action_settings"
        android:icon="@drawable/ic_launcher"
        android:orderInCategory="100"
        android:showAsAction="ifRoom|withText"
        android:title="@string/action_settings">
        <menu >
            <item 
                android:id="@+id/create_new"
                android:title="新建文件夹">                
            </item>
            <item 
                android:id="@+id/open"
                android:title="打开文件夹">                
            </item>  
        </menu>    
    </item>
    <item 
        android:id="@+id/sys"
        android:icon="@drawable/ic_launcher"
        android:orderInCategory="101"
        android:showAsAction="never"
        android:title="用户菜单">
        <menu>
            <group 
                android:id="@+id/group1">
                <item 
                    android:id="@+id/load"
                    android:title="加载文件">
                </item>
            </group>
            <group 
                android:id="@+id/group2">
                <item 
                    android:id="@+id/save"
                    android:title="保存文件">
                </item>
            </group>
        </menu>
    </item>
</menu>

MainActivity.java

package cn.edu.aynu.rjxy;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case R.id.create_new:
            //加载意图
            //Intent intent = new Intent(MainActivity.this,LoginActivity.class);
            //item.setIntent(intent);
            Toast.makeText(MainActivity.this, "新建文件夹", 0).show();
            break;
        case R.id.load:
            Toast.makeText(MainActivity.this, "加载文件夹", 0).show();
            break;
        case R.id.open:
            Toast.makeText(MainActivity.this, "打开文件夹", 0).show();
            break;
        case R.id.save:
            Toast.makeText(MainActivity.this, "保存文件夹", 0).show();
            break;

        default:
            break;
        }
        return super.onOptionsItemSelected(item);
    }
    
}

案例三代码：

下面代码的改写位置同上面的一样。

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

    <item
        android:id="@+id/edit"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="edit"/>
    <item
        android:id="@+id/share"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="share"/>
    <item
        android:id="@+id/delete"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="delete"/>

</menu>

MainActivity.java

package cn.edu.aynu.rjxy.activity;

import java.util.ArrayList;
import java.util.List;

import cn.edu.aynu.rjxy.activity.R.menu;

import android.os.Bundle;
import android.R.anim;
import android.app.Activity;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class MainActivity extends Activity {
    private ListView listview;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listview = (ListView) findViewById(R.id.listView1);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, getData());
        listview.setAdapter(adapter);
        //给listview注册上下文菜单
        registerForContextMenu(listview);
    }
    public List<String> getData(){
        List<String> list = new ArrayList<String>();
        for (int i = 0; i < 7; i++) {
            list.add("jack"+i);
        }
        return list;
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v,
            ContextMenuInfo menuInfo) {
        //加载xml中的上下文菜单
        super.onCreateContextMenu(menu, v, menuInfo);
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main, menu);
    }
    @Override
    public boolean onContextItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case R.id.edit:
            Toast.makeText(MainActivity.this, "edit", 0).show();
            break;
        case R.id.share:
            Toast.makeText(MainActivity.this, "share", 0).show();
            break;
        case R.id.delete:
            Toast.makeText(MainActivity.this, "delete", 0).show();
            break;
        default:
            break;
        }
        return super.onContextItemSelected(item);
    }
}