用PopupWindow实现下拉列表

<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:background="#10000000"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="10dp"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/tv_content"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:layout_marginLeft="10dp"
            android:layout_weight="1"
            android:background="@color/white"
            android:padding="6dp"
            android:textColor="#cc000000"
            android:textSize="17sp" />

        <ImageButton
            android:id="@+id/btn_popup_spinner"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_marginRight="10dp"
            android:layout_gravity="center_vertical"
            android:background="@drawable/down_arrow" />
    </LinearLayout>
</LinearLayout>

public class PopupSpinnerActivity extends Activity {
	private TextView tv_content;
	private PopupWindow popupMenu;
	private ListView mListView; //下拉列表的ListView
	private ArrayList<String> contentListData;
	private MyPopupDataAdapter adapter;
	private ImageButton btn_popupmenu;

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

		initPopupSpinnerView();
}

     /**
	 * 初始化控件
	 */
	private void initPopupSpinnerView() {
		tv_content = (TextView) findViewById(R.id.tv_content);
		btn_popupmenu = (ImageButton) findViewById(R.id.btn_popup_spinner);
//		tv_content.getPaint().setFlags(Paint.UNDERLINE_TEXT_FLAG);//加下划线
//		tv_content.getPaint().setAntiAlias(true); //抗锯齿
		btn_popupmenu.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				showSelectPoupWindow();
			}
		});
	}

	/**
	 * 设置下拉列表及内容
	 */
	private void showSelectPoupWindow() {
		initPopupListData();

		popupMenu = new PopupWindow(mListView, tv_content.getWidth() + btn_popupmenu.getWidth(), 200);
		popupMenu.setOutsideTouchable(true);//设置外部可被点击
		popupMenu.setFocusable(true);
		popupMenu.setBackgroundDrawable(new BitmapDrawable());
		popupMenu.showAsDropDown(tv_content, 0, 0); //对齐此控件,后两个参数是距离控件的左和上下距离
	}

	private void initPopupListData() {
		mListView = new ListView(this);
		mListView.setDividerHeight(1);
		mListView.setVerticalScrollBarEnabled(false); //消除滚动条
		//mListView.setBackgroundResource(R.drawable.popup_listview_background);

		contentListData = new ArrayList<String>();
		for (int i = 0; i < 20; i++) {
			String content = "popup list item data  " + i;
			contentListData.add(content);
		}

		adapter = new MyPopupDataAdapter();
		mListView.setAdapter(adapter);
		mListView.setOnItemClickListener(new OnItemClickListener() {
			@Override
			public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
				Toast.makeText(getApplicationContext(), "点击了item " + position, Toast.LENGTH_SHORT).show();
				String itemContent = contentListData.get(position);
				tv_content.setText(itemContent);
				popupMenu.dismiss();
			}
		});
	}

	public class MyPopupDataAdapter extends BaseAdapter {

		@Override
		public int getCount() {
			return contentListData == null ? 0 : contentListData.size();
		}

		@Override
		public Object getItem(int position) {
			return contentListData.get(position);
		}

		@Override
		public long getItemId(int position) {
			return position;
		}

		@Override
		public View getView(final int position, View convertView, ViewGroup parent) {
			ViewHolder holder = null;
			if (convertView == null) {
				convertView = View.inflate(PopupSpinnerActivity.this, R.layout.popup_list_item, null);
				holder = new ViewHolder();
				holder.tv_value = (TextView) convertView.findViewById(R.id.tv_value);
				holder.btn_delete = (ImageButton) convertView.findViewById(R.id.btn_delete);
				convertView.setTag(holder);
			} else {
				holder = (ViewHolder) convertView.getTag();
			}
			holder.tv_value.setText(contentListData.get(position));
			holder.btn_delete.setOnClickListener(new OnClickListener() {
				@Override
				public void onClick(View v) {
					contentListData.remove(position);
					adapter.notifyDataSetChanged();
					if (contentListData.size() == 0) {
						popupMenu.dismiss();
					}
				}
			});
			return convertView;
		}

		class ViewHolder {
			TextView tv_value;
			ImageButton btn_delete;
		}
	}
}