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. packagecn.winfirm.examples.base;
   
2. 
   
3. importandroid.app.Activity;
   
4. importandroid.app.ProgressDialog;
   
5. importandroid.content.DialogInterface;
   
6. importandroid.content.DialogInterface.OnKeyListener;
   
7. importandroid.os.Bundle;
   
8. importandroid.view.KeyEvent;
   
9. importandroid.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. publicclassBaseActivityextendsActivity{
    
18. 
    
19. privateProgressDialog progressDialog=null;
    
20. 
    
21. @Override
    
22. protectedvoidonCreate(Bundle savedInstanceState){
    
23. super.onCreate(savedInstanceState);
    
24. requestWindowFeature(Window.FEATURE_NO_TITLE);
    
25. }
    
26. 
    
27. /**
    
28. * show loading progress dialog
    
29. */
    
30. publicvoidshowDialog(){
    
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. privateOnKeyListener onKeyListener=newOnKeyListener(){
    
44. @Override
    
45. publicbooleanonKey(DialogInterfacedialog,intkeyCode,KeyEventevent){
    
46. if(keyCode==KeyEvent.KEYCODE_BACK&&event.getAction()==KeyEvent.ACTION_DOWN){
    
47. dismissDialog();
    
48. }
    
49. returnfalse;
    
50. }
    
51. };
    
52. 
    
53. /**
    
54. * dismiss dialog
    
55. */
    
56. publicvoiddismissDialog(){
    
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. publicvoidonBackPressed(){
    
70. if(progressDialog!=null&&progressDialog.isShowing()){
    
71. dismissDialog();
    
72. }else{
    
73. super.onBackPressed();
    
74. }
    
75. }
    
76. }