最近看到新浪微博顶部栏的微博分组效果很炫，从网上查了一些资料明白原来是用PopupWindow实现的，今天自己也写了一个例子实现了这种效果，希望对大家有帮助。

         PopupWindow就是弹出窗口的意思，类似windows下面的开始按钮。PopupWindow可以实现浮层效果，而且可以自定义显示位置，出现和退出时的动画.

            首先定义新浪微博的顶部栏,title_two_button.xml和main.xml

<?xml version="1.0" encoding="utf-8"?><FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="wrap_content" >    <TextView        android:id="@+id/tvtitle"        android:layout_width="fill_parent"        android:layout_height="45dip"        android:background="@drawable/search_bg"        android:gravity="center"        android:text="天堂没有路"        android:textColor="@color/black"        android:textSize="25dip" />    <Button        android:id="@+id/btn_title_left"        android:layout_width="50dip"        android:layout_height="35dip"        android:layout_gravity="center_vertical"        android:background="@drawable/title_button"        android:textColor="@color/white" />    <Button        android:id="@+id/btn_title_right"        android:layout_width="50dip"        android:layout_height="35dip"        android:layout_gravity="right"        android:layout_marginRight="2dip"        android:layout_marginTop="4dip"        android:background="@drawable/title_button2"        android:textColor="@color/white" /></FrameLayout>

<?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="fill_parent"    android:background="@android:color/white"    android:orientation="vertical" >    <include        android:id="@+id/top_title"        layout="@layout/title_two_button" /></LinearLayout>

接下来定义弹出对话框的布局文件group_list.xml和group_item_view.xml

<?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="fill_parent"    android:background="@drawable/group_bg"    android:orientation="vertical"     >    <ImageView        android:id="@+id/iv_group_list_bg_divider"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:background="@drawable/group_divider"         />    <ListView        android:id="@+id/lvGroup"        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:divider="@drawable/group_divider"          /></LinearLayout>

<?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="@dimen/group_item_height"    android:orientation="vertical" >    <TextView        android:id="@+id/groupItem"       android:textColor="#ffffff"       android:textSize="18dp"        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:gravity="center" /></LinearLayout>

自定义一个适配器：GroupAdapter

import java.util.List;import cn.com.karl.popwindow.R;import android.content.Context;import android.graphics.Color;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.TextView;public class GroupAdapter extends BaseAdapter {	private Context context;	private List<String> list;	public GroupAdapter(Context context, List<String> list) {		this.context = context;		this.list = list;	}	@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 viewGroup) {				ViewHolder holder;		if (convertView==null) {			convertView=LayoutInflater.from(context).inflate(R.layout.group_item_view, null);			holder=new ViewHolder();						convertView.setTag(holder);						holder.groupItem=(TextView) convertView.findViewById(R.id.groupItem);					}		else{			holder=(ViewHolder) convertView.getTag();		}		holder.groupItem.setTextColor(Color.BLACK);		holder.groupItem.setText(list.get(position));				return convertView;	}	static class ViewHolder {		TextView groupItem;	}}

最后是我要实现弹出对话框的核心类PoupWindowDemoActivity

import java.util.ArrayList;import java.util.List;import cn.com.karl.adapter.GroupAdapter;import android.app.Activity;import android.content.Context;import android.graphics.drawable.BitmapDrawable;import android.os.Bundle;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.Window;import android.view.WindowManager;import android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.ListView;import android.widget.PopupWindow;import android.widget.TextView;import android.widget.Toast;public class PoupWindowDemoActivity extends Activity {	private PopupWindow popupWindow;	private ListView lv_group;	private View view;	private View top_title;	private TextView tvtitle;	private List<String> groups;	public void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		this.requestWindowFeature(Window.FEATURE_NO_TITLE);		setContentView(R.layout.main);		top_title = this.findViewById(R.id.top_title);		tvtitle = (TextView) top_title.findViewById(R.id.tvtitle);		tvtitle.setText("天堂没有路");		tvtitle.setOnClickListener(new View.OnClickListener() {			@Override			public void onClick(View v) {				showWindow(v);			}		});	}		private void showWindow(View parent) {		if (popupWindow == null) {			LayoutInflater layoutInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);			view = layoutInflater.inflate(R.layout.group_list, null);			lv_group = (ListView) view.findViewById(R.id.lvGroup);			// 加载数据			groups = new ArrayList<String>();			groups.add("全部");			groups.add("我的微博");			groups.add("好友");			groups.add("亲人");			groups.add("同学");			groups.add("朋友");			groups.add("陌生人");			GroupAdapter groupAdapter = new GroupAdapter(this, groups);			lv_group.setAdapter(groupAdapter);			// 创建一个PopuWidow对象			popupWindow = new PopupWindow(view, 300, 350);		}		// 使其聚集		popupWindow.setFocusable(true);		// 设置允许在外点击消失		popupWindow.setOutsideTouchable(true);		// 这个是为了点击“返回Back”也能使其消失，并且并不会影响你的背景		popupWindow.setBackgroundDrawable(new BitmapDrawable());		WindowManager windowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);		// 显示的位置为:屏幕的宽度的一半-PopupWindow的高度的一半		int xPos = windowManager.getDefaultDisplay().getWidth() / 2				- popupWindow.getWidth() / 2;		Log.i("coder", "xPos:" + xPos);		popupWindow.showAsDropDown(parent, xPos, 0);		lv_group.setOnItemClickListener(new OnItemClickListener() {			@Override			public void onItemClick(AdapterView<?> adapterView, View view,					int position, long id) {				Toast.makeText(PoupWindowDemoActivity.this,						groups.get(position), 1000)						.show();				if (popupWindow != null) {					popupWindow.dismiss();				}			}		});	}}

这样就完成了一个弹出对话框的效果，下面来看一下吧！

再看一张新浪微博的弹出对话框效果：

已经完成，我们可以把这项功能加入自己的做的新浪微博里，为自己的应用增添点特色色彩吧！