Android高手进阶教程(十)之----Android PopupWindow的使用!!!

大家好，我们这一节讲的是Android PopupWindow的使用! 在我理解其实PopupWindow其实类似于一个不能动的Widget(仅从显示效果来说!)

它是浮在别的窗口之上的.

下面我将给大家做一个简单的Demo，类似于音乐播放器的Widget的效果，点击Button的时候出来PopupWindow,首先我们看一下效果图:

package com.android.tutor;  
import android.app.Activity;  
import android.content.Context;  
import android.os.Bundle;  
import android.view.Gravity;  
import android.view.LayoutInflater;  
import android.view.View;  
import android.view.View.OnClickListener;  
import android.view.ViewGroup.LayoutParams;  
import android.widget.Button;  
import android.widget.PopupWindow;  
public class PopupWindowDemo extends Activity  implements OnClickListener{  
    private Button btn;  
      
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
          
        btn = (Button)findViewById(R.id.btn);  
        btn.setOnClickListener(this);  
    }  
    @Override  
    public void onClick(View v) {  
        Context mContext = PopupWindowDemo.this;  
        if (v.getId() == R.id.btn) {  
            LayoutInflater mLayoutInflater = (LayoutInflater) mContext  
                    .getSystemService(LAYOUT_INFLATER_SERVICE);  
            View music_popunwindwow = mLayoutInflater.inflate(  
                    R.layout.music_popwindow, null);  
            PopupWindow mPopupWindow = new PopupWindow(music_popunwindwow, LayoutParams.FILL_PARENT,  
                    LayoutParams.WRAP_CONTENT);  
              
            mPopupWindow.showAtLocation(findViewById(R.id.main), Gravity.RIGHT|Gravity.BOTTOM, 0, 0);  
        }  
    }  
}

需要强调的是这里PopupWindow必须有某个事件触发才会显示出来，不然总会抱错，不信大家可以试试!

随着这个问题的出现，就会同学问了，那么我想初始化让PopupWindow显示出来，那怎么办了，不去寄托于其他点击事件，

在这里我用了定时器Timer来实现这样的效果,当然这里就要用到Handler了，如果大家不理解的可以返回

package com.android.tutor;  
import java.util.Timer;  
import java.util.TimerTask;  
import android.app.Activity;  
import android.content.Context;  
import android.os.Bundle;  
import android.os.Handler;  
import android.os.Message;  
import android.view.Gravity;  
import android.view.LayoutInflater;  
import android.view.View;  
import android.view.ViewGroup.LayoutParams;  
import android.widget.PopupWindow;  
public class PopupWindowDemo extends Activity{  
    private Handler mHandler = new Handler(){  
          
        public void handleMessage(Message msg) {  
            switch (msg.what) {  
            case 1:  
                showPopupWindow();  
                break;  
            }  
        };  
    };  
      
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
          
        //create the timer   
        Timer timer = new Timer();  
        timer.schedule(new initPopupWindow(), 100);  
    }  
      
    private class initPopupWindow extends TimerTask{  
        @Override  
        public void run() {  
              
            Message message = new Message();  
            message.what = 1;  
            mHandler.sendMessage(message);  
              
        }         
    }  
      
      
    public void showPopupWindow() {  
        Context mContext = PopupWindowDemo.this;  
        LayoutInflater mLayoutInflater = (LayoutInflater) mContext  
                .getSystemService(LAYOUT_INFLATER_SERVICE);  
        View music_popunwindwow = mLayoutInflater.inflate(  
                R.layout.music_popwindow, null);  
        PopupWindow mPopupWindow = new PopupWindow(music_popunwindwow,  
                LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);  
        mPopupWindow.showAtLocation(findViewById(R.id.main), Gravity.CENTER, 0, 0);  
    }  
}