PopupWindow是一个弹出式窗口，它可以展示任意View。他会浮在当前窗口的上方展示。

下面看代码：
复制代码 代码如下:
public class MyActivity extends Activity{
private PopupWindow menu;
private LayoutInflater inflater;
private View layout;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

setContentView(R.layout.main);

//实例化PopupWindow创建菜单

initMenu();

}
//判断按键 菜单的显示与隐藏
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(!menu.isShowing()&&keyCode == KeyEvent.KEYCODE_MENU){
show();
}else{
menu.dismiss();
}
if(keyCode == KeyEvent.KEYCODE_BACK&&menu.isShowing()){
menu.dismiss();
}
return true;

}
//实例化PopupWindow创建菜单
private void initMenu(){
//获取LayoutInflater实例
inflater = (LayoutInflater) this.getSystemService(LAYOUT_INFLATER_SERVICE);
//获取弹出菜单的布局
layout = inflater.inflate(R.layout.menu,null);
//设置popupWindow的布局
menu = new PopupWindow(layout, WindowManager.LayoutParams.WRAP_CONTENT,WindowManager.LayoutParams.WRAP_CONTENT);
}
//显示菜单
private void show(){
//设置位置
menu.showAtLocation(this.findViewById(R.id.main), Gravity.BOTTOM|Gravity.CENTER_HORIZONTAL,0,0); //设置在屏幕中的显示位置
}
}

菜单的布局文件：

复制代码 代码如下:
<?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:orientation="horizontal"

>

<ImageView

android:id="@+id/icon_1"

android:background="@drawable/icon_1"

android:layout_width="40dp"

android:layout_height="40dp"/>

<ImageView

android:id="@+id/icon_2"

android:background="@drawable/icon_2"

android:layout_width="40dp"

android:layout_height="40dp"/>

<ImageView

android:id="@+id/icon_3"

android:background="@drawable/icon3"

android:layout_width="40dp"

android:layout_height="40dp"/>

<ImageView

android:id="@+id/icon_4"

android:background="@drawable/icon4"

android:layout_width="40dp"

android:layout_height="40dp"/>
</LinearLayout>