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：

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

}

}

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菜单的布局文件：

<?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="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>

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