主布局

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.popupwindow.MainActivity"
    android:id="@+id/main" >
    <!-- 注意这里要设置布局文件的id为main,后面要调用到 -->
    <!-- 定义按钮和点击事件 -->
    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="135dp"
        android:text="打开PopupWindow" 
        android:onClick="openPopupWindow"
        />
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="@drawable/aa" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="这是PopupWindow" 
        android:textSize="30dp"
        android:textColor="#823627"/>
</LinearLayout>

package com.example.popupwindow;

import android.app.Activity;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.PopupWindow;

public class MainActivity extends Activity {

	private PopupWindow popupWindow;
	private View parent;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		/*
		 * 得到布局填充符getLayoutInflater()，也可通过系统服务getSystemService(name)得到
		 * inflate指定布局文件的id
		 */
		View contentView = getLayoutInflater().inflate(R.layout.popup_window, null);
		/*
		 * 第一个参数:PopupWindow要显示的界面
		 * 第二个参数:PopupWindow的宽
		 * 第三个参数:PopupWindow的高
		 */
		popupWindow = 
				new PopupWindow(contentView, ViewGroup.LayoutParams.MATCH_PARENT,
						ViewGroup.LayoutParams.WRAP_CONTENT);
		popupWindow.setFocusable(true);
		//让小窗口取得焦点，不然怎么点也不会有反应
		popupWindow.setBackgroundDrawable(new BitmapDrawable());
        //点空白处关掉Popup窗口，在背景new一个位图对象就可以了
		parent = this.findViewById(R.id.main);
		//以上main为当前Activity对应的布局文件
	}
	public void openPopupWindow(View v){
         //显示PopupWindow的方法要多个，可设置具体显示位置方式
		popupWindow.showAtLocation(parent, Gravity.BOTTOM, 0, 0);
	}
}

点击按钮

Android对话框（四）PopupWindow