Android自定义spinner下拉框实现的实现

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;@Overrideprotected 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() {@Overridepublic void onDismiss() {setTextImage(R.drawable.icon_down);}};/** * popupwindow显示的ListView的item点击事件 */private OnItemClickListener itemClickListener = new OnItemClickListener() {@Overridepublic 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() {@Overridepublic 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{@Overridepublic int getCount() {return list.size();}@Overridepublic Object getItem(int position) {return list.get(position);}@Overridepublic long getItemId(int position) {return position;}@Overridepublic 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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