Android 自定义spinner下拉框实现

一:前言
本人参考博客:http://blog.csdn.net/jdsjlzx/article/details/41316417 最近在弄一个下拉框,发现Android自带的很难实现我的功能,于是去网上找到一份Demo,但是发现没有封装的好,并且还有很多重复的代码,于是我在这位前辈的基础上进行了修改.并且重新进行了封装,代码变得简单,并且具有可读性.

二:实现原理
1.就是一个TextView 弄一个弧形的背景图片,然后设置一个点击事件.
2.点击TextView之后显示一个PopupWindow,Popupwindow是自定义的,里面显示一个ListView.ListView也设置了左边.右边.底部的边框.

三:效果图如下

四:代码实现:

1).MainActivity.java  程序入口,初始化数据,初始化自定义PopupWIndow,TextView点击之后显示PopupWIndow,处理ListView的点击事件.

/** 
 * 主Activity  用来实现popupwindow 
 * @author ansen 
 */  
public class MainActivity extends Activity {  
    private SpinerPopWindow<String> mSpinerPopWindow;  
    private List<String> list;  
    private TextView tvValue;  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
  
        initData();  
  
        tvValue = (TextView) findViewById(R.id.tv_value);  
        tvValue.setOnClickListener(clickListener);  
        mSpinerPopWindow = new SpinerPopWindow<String>(this, list,itemClickListener);  
        mSpinerPopWindow.setOnDismissListener(dismissListener);  
    }  
      
    /** 
     * 监听popupwindow取消 
     */  
    private OnDismissListener  dismissListener=new OnDismissListener() {  
        @Override  
        public void onDismiss() {  
            setTextImage(R.drawable.icon_down);  
        }  
    };  
  
    /** 
     * popupwindow显示的ListView的item点击事件 
     */  
    private OnItemClickListener itemClickListener = new OnItemClickListener() {  
        @Override  
        public void onItemClick(AdapterView<?> parent, View view, int position,long id) {  
            mSpinerPopWindow.dismiss();  
            tvValue.setText(list.get(position));  
            Toast.makeText(MainActivity.this, "点击了:" + list.get(position),Toast.LENGTH_LONG).show();  
        }  
    };  
  
    /** 
     * 显示PopupWindow 
     */  
    private OnClickListener clickListener = new OnClickListener() {  
        @Override  
        public void onClick(View v) {  
            switch (v.getId()) {  
            case R.id.tv_value:  
                mSpinerPopWindow.setWidth(tvValue.getWidth());  
                mSpinerPopWindow.showAsDropDown(tvValue);  
                setTextImage(R.drawable.icon_up);  
                break;  
            }  
        }  
    };  
  
    /** 
     * 初始化数据 
     */  
    private void initData() {  
        list = new ArrayList<String>();  
        for (int i = 0; i < 5; i++) {  
            list.add("test:" + i);  
        }  
    }  
  
    /** 
     * 给TextView右边设置图片 
     * @param resId 
     */  
    private void setTextImage(int resId) {  
        Drawable drawable = getResources().getDrawable(resId);  
        drawable.setBounds(0, 0, drawable.getMinimumWidth(),drawable.getMinimumHeight());// 必须设置图片大小，否则不显示  
        tvValue.setCompoundDrawables(null, null, drawable, null);  
    }  
}  

2).activity_main.xml  这个文件也没啥好说的  就是两个TextView。

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    xmlns:tools="http://schemas.android.com/tools"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:orientation="vertical" >  
    <LinearLayout  
        android:layout_width="match_parent"  
        android:layout_height="wrap_content"  
        android:layout_margin="5dp"  
        android:orientation="horizontal">  
  
        <TextView  
            android:id="@+id/tv_value"  
            android:layout_width="0dp"  
            android:layout_height="wrap_content"  
            android:layout_weight="1"  
            android:background="@drawable/shape_help_category_tv_bg"  
            android:drawableRight="@drawable/icon_down"  
            android:padding="10dp"  
            android:textColor="@color/content_color"  
            android:text="请选择父类别"  
            android:textSize="20sp"/>  
  
        <TextView  
            android:layout_marginLeft="5dp"  
            android:layout_width="0dp"  
            android:layout_height="wrap_content"  
            android:layout_weight="1"  
            android:background="@drawable/shape_help_category_tv_bg"  
            android:drawableRight="@drawable/icon_down"  
            android:textColor="@color/content_color"  
            android:padding="10dp"  
            android:text="请选择子类别"  
            android:textSize="20sp" />  
    </LinearLayout>  
</LinearLayout>  

3).SpinerPopWindow.java  自定义Popupwindow类 初始化PopupWindow显示的布局,以及一些参数,并且给listView设置适配器

 * 自定义PopupWindow  主要用来显示ListView  
 * @author Ansen  
 * @param <T>  
 * @param <T>  
 * @create time 2015-11-3  
 */  
public class SpinerPopWindow<T> extends PopupWindow {  
    private LayoutInflater inflater;  
    private ListView mListView;  
    private List<T> list;  
    private MyAdapter  mAdapter;  
      
    public SpinerPopWindow(Context context,List<T> list,OnItemClickListener clickListener) {  
        super(context);  
        inflater=LayoutInflater.from(context);  
        this.list=list;  
        init(clickListener);  
    }  
      
    private void init(OnItemClickListener clickListener){  
        View view = inflater.inflate(R.layout.spiner_window_layout, null);  
        setContentView(view);         
        setWidth(LayoutParams.WRAP_CONTENT);  
        setHeight(LayoutParams.WRAP_CONTENT);  
        setFocusable(true);  
            ColorDrawable dw = new ColorDrawable(0x00);  
        setBackgroundDrawable(dw);  
        mListView = (ListView) view.findViewById(R.id.listview);  
        mListView.setAdapter(mAdapter=new MyAdapter());  
        mListView.setOnItemClickListener(clickListener);  
    }  
      
    private class MyAdapter extends BaseAdapter{  
        @Override  
        public int getCount() {  
            return list.size();  
        }  
  
        @Override  
        public Object getItem(int position) {  
            return list.get(position);  
        }  
  
        @Override  
        public long getItemId(int position) {  
            return position;  
        }  
  
        @Override  
        public View getView(int position, View convertView, ViewGroup parent) {  
            ViewHolder holder=null;  
            if(convertView==null){  
                holder=new ViewHolder();  
                convertView=inflater.inflate(R.layout.spiner_item_layout, null);  
                holder.tvName=(TextView) convertView.findViewById(R.id.tv_name);  
                convertView.setTag(holder);  
            }else{  
                holder=(ViewHolder) convertView.getTag();  
            }  
            holder.tvName.setText(getItem(position).toString());  
            return convertView;  
        }  
    }  
      
    private class ViewHolder{  
        private TextView tvName;  
    }  
}  

4).spiner_window_layout.xml    PopupWindow显示的布局文件 里面就一个ListView控件

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="fill_parent"  
    android:layout_height="wrap_content"  
    android:layout_alignParentRight="true"  
    android:orientation="vertical">  
  
    <ListView  
        android:id="@+id/listview"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:cacheColorHint="#00000000"  
        android:background="@drawable/shape_popupwindow_list_bg"  
        android:scrollbars="none" >  
    </ListView>  
</LinearLayout>  

还有一些其他布局,我就不一一贴出来了,有兴趣的可以去看看源码.这个Demo还是比较简单的,相信大家都能看懂.
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