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：
下面是核心代码：
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《Android高手进阶教程》9.Android Handler的使用，看一看，加深了解：
下面是核心代码：
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);
}
}
效果如下图：
这样就可以初始化PopupWindow了，呵呵，这一节的布局文件有点多
