让ProgressDialog在setCancelable(false)时按返回键可dismiss

最近发现Android4.0系统中ProgressDialog设置为setCancelable(true)时，点击ProgressDialog以外的区域也可以让ProgressDialog dismiss掉。但有时我们不希望是这样的效果，于是将ProgressDialog设置setCancelable(false)，再点击ProgressDialog以外的区域就不会出现前面所说的情况了，然而这样以来再按返回键时就不起作用了，只能等待程序执行到dissmiss处为止。其实，只要为ProgressDialog添加KeyListener来对返回键予以处理就可以解决这个问题了。

1. package cn.winfirm.examples.base;
   
2. 
   
3. import android.app.Activity;
   
4. import android.app.ProgressDialog;
   
5. import android.content.DialogInterface;
   
6. import android.content.DialogInterface.OnKeyListener;
   
7. import android.os.Bundle;
   
8. import android.view.KeyEvent;
   
9. import android.view.Window;
   
10. 
    
11. /**
    
12.  * Activity的基类，带一个ProgressDialog，可双击取消其显示
    
13.  *
    
14.  * @author savant
    
15.  *
    
16.  */
    
17. public class BaseActivityextends Activity{
    
18. 
    
19.     private ProgressDialog progressDialog = null;
    
20. 
    
21.     @Override
    
22.     protected void onCreate(Bundle savedInstanceState){
    
23.         super.onCreate(savedInstanceState);
    
24.         requestWindowFeature(Window.FEATURE_NO_TITLE);
    
25.     }
    
26. 
    
27.     /**
    
28.      * show loading progress dialog
    
29.      */
    
30.     public voidshowDialog(){
    
31.         if (null== progressDialog){
    
32.             progressDialog = ProgressDialog.show(BaseActivity.this,"", "正在加载，请稍候...");
    
33.             progressDialog.setCancelable(false);
    
34.         } else{
    
35.             progressDialog.show();
    
36.         }
    
37.         progressDialog.setOnKeyListener(onKeyListener);
    
38.     }
    
39. 
    
40.     /**
    
41.      * add a keylistener for progress dialog
    
42.      */
    
43.     private OnKeyListener onKeyListener = new OnKeyListener(){
    
44.         @Override
    
45.         public boolean onKey(DialogInterface dialog, int keyCode,KeyEvent event){
    
46.             if (keyCode ==KeyEvent.KEYCODE_BACK&& event.getAction()== KeyEvent.ACTION_DOWN){
    
47.                 dismissDialog();
    
48.             }
    
49.             return false;
    
50.         }
    
51.     };
    
52. 
    
53.     /**
    
54.      * dismiss dialog
    
55.      */
    
56.     public void dismissDialog(){
    
57.         if (isFinishing()){
    
58.             return;
    
59.         }
    
60.         if (null!= progressDialog&& progressDialog.isShowing()){
    
61.             progressDialog.dismiss();
    
62.         }
    
63.     }
    
64. 
    
65.     /**
    
66.      * cancel progress dialog if nesseary
    
67.      */
    
68.     @Override
    
69.     public void onBackPressed(){
    
70.         if (progressDialog!= null && progressDialog.isShowing()){
    
71.             dismissDialog();
    
72.         } else{
    
73.             super.onBackPressed();
    
74.         }
    
75.     }
    
76. }