Android开发中PopupWindow用法实例分析

private TextView tv_appmanager_title;
private ListView lv_app_manager;
private LinearLayout ll_appmanager_loading;
private AppManagerProvider provider;
private List<AppManagerInfo> infos ;
private AppManagerAdapter adapter;
private PopupWindow localPopupWindow;
private Handler handler = new Handler(){
  public void handleMessage(android.os.Message msg) {
    switch (msg.what) {
    case Constants.MSG_APP_MANAGER:
      ll_appmanager_loading.setVisibility(View.INVISIBLE);
      adapter = new AppManagerAdapter(infos, AppManagerActivity.this);
      lv_app_manager.setAdapter(adapter);
      break;
    }
  };
};
@Override
protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.appmanager);
  lv_app_manager = (ListView) this.findViewById(R.id.lv_app_manager);
  ll_appmanager_loading = (LinearLayout) this.findViewById(R.id.ll_appmanager_loading);
  ll_appmanager_loading.setVisibility(View.VISIBLE);
  new Thread(){
    public void run() {
      provider = new AppManagerProvider(AppManagerActivity.this);
      infos = provider.getAppManagerInfo();
      Message msg = new Message();
      msg.what = Constants.MSG_APP_MANAGER;
      handler.sendMessage(msg);
    };
  }.start();
  lv_app_manager.setOnItemClickListener(new OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> parent, View view,
        int position, long id) {
      if(null != localPopupWindow){
        localPopupWindow.dismiss();
        localPopupWindow = null;
      }
      int [] location = new int[2];
      view.getLocationInWindow(location);
      int x = location[0] + 60;
      int y = location[1];
      TextView tv = new TextView(AppManagerActivity.this);
      AppManagerInfo info = (AppManagerInfo) lv_app_manager.getItemAtPosition(position);
      tv.setText(info.getPackName());
      tv.setTextSize(20);
      tv.setTextColor(Color.RED);
      localPopupWindow = new PopupWindow(tv, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
      Drawable background = new ColorDrawable(Color.GRAY);
      localPopupWindow.setBackgroundDrawable(background);
      localPopupWindow.showAtLocation(tv, 51, x, y);
    }
  });
  lv_app_manager.setOnScrollListener(new OnScrollListener() {
    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
      if(null != localPopupWindow){
        localPopupWindow.dismiss();
        localPopupWindow = null;
      }
    }
    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
        int visibleItemCount, int totalItemCount) {
      if(null != localPopupWindow){
        localPopupWindow.dismiss();
        localPopupWindow = null;
      }
    }
  });
}