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 = ; i < ; 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(, , 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=""
            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=""
            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 --
 */
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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