Handler对象的Message运用

Handler对象的Message应用

知识点

???? 接受子线程发送的消息数据，并用此消息数据配合主线程更新UI。

???? 根据消息数据中的标识msg.what，分类处理相应的操作。

?

范例程序

??? 为了让线程对象Runnable运行过程中，可以不断地将信息往Activity传递，所以用了Android.os.Handler对象及Android.os.Message对象，且在类成员变量中声明了两个整数：STOP_NOTIFIER与RUNNING_NOTIFIER，这两个整数将作为信息传递出来时的信号标识，前者为线程对象Runnable需要喊停的标识，后者为线程对象Runnable正在运行的标识。

??? 本范例中，摆放一个按钮和一个进度条控件。按钮用于复位参数和启动线程对象Runnable。

具体代码如下：

?

1. package?com.lyg.progressbarhandler;??
2. ??
3. import?android.app.Activity;??
4. import?android.os.Bundle;??
5. import?android.os.Handler;??
6. import?android.os.Message;??
7. import?android.util.Log;??
8. import?android.view.View;??
9. import?android.view.View.OnClickListener;??
10. import?android.view.Window;??
11. import?android.view.WindowManager;??
12. import?android.widget.Button;??
13. import?android.widget.ProgressBar;??
14. ??
15. public?class?progressBarHandler?extends?Activity?{??
16. ????/**?Called?when?the?activity?is?first?created.?*/??
17. ????/*?自定义Handler信息代码，作为标识事件处理?*/??
18. ????protected?static?final?int?STOP_NOTIFIER?=?0x108;//停止标识??
19. ????protected?static?final?int?RUNNING_NOTIFIER?=?0x109;//运行标识??
20. ??
21. ????private?Button?bnStart;??
22. ????private?ProgressBar?progBar;??
23. ??????
24. ????@Override??
25. ????public?void?onCreate(Bundle?savedInstanceState)?{??
26. ????????super.onCreate(savedInstanceState);??
27. ??????????
28. ????????//全屏显示??
29. ????????//?注：以下两行不可放在setContentView之后，否则报错。??
30. ????????requestWindowFeature(Window.FEATURE_NO_TITLE);??
31. ????????getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,??
32. ????????????????WindowManager.LayoutParams.FLAG_FULLSCREEN);??
33. ??
34. ????????setContentView(R.layout.main);??
35. ??
36. ????????progBar?=?(ProgressBar)?findViewById(R.id.progressbar);??
37. ????????bnStart?=?(Button)?findViewById(R.id.bnstart);??
38. ????????bnStart.setOnClickListener(new?bnStartOnClickListener());??
39. ??
40. ????????//?初始化进度条控件??
41. ????????progBar.setProgress(0);??
42. ??
43. ????}??
44. ??????
45. ????class?bnStartOnClickListener?implements?OnClickListener{??
46. ??
47. ????????@Override??
48. ????????public?void?onClick(View?arg0)?{??
49. ????????????//?TODO?Auto-generated?method?stub??
50. ????????????//线程调用跟踪??
51. ????????????Log.d("lyg",?"onClick-->id="+Thread.currentThread().getId()+"?name="+Thread.currentThread().getName());??
52. ??????????????
53. ????????????progBar.setProgress(0);//设置进度控件当前进度为0??
54. ??????????????
55. ????????????//将线程对象runable放到消息队列中??
56. ????????????handler.post(runable);??
57. ????????}??
58. ????}??
59. ??????
60. ????//Handler构建之后，会监听传来的消息??
61. ????Handler?handler=new?Handler(){??
62. ????????@Override??
63. ????????public?void?handleMessage(Message?msg)?{??
64. ????????????//?TODO?Auto-generated?method?stub??
65. ????????????super.handleMessage(msg);??
66. ????????????System.out.println("Handler?handleMessage");??
67. ????????????switch(msg.what)??
68. ????????????{??
69. ????????????????case?STOP_NOTIFIER:??
70. ????????????????{??
71. ????????????????????progBar.setProgress(msg.arg1);//设置进度控件的当前进度为msg.arg1??
72. ????????????????????handler.removeCallbacks(runable);//清除队列中的未执行的runable??
73. ????????????????}??
74. ????????????????break;??
75. ????????????????case?RUNNING_NOTIFIER:??
76. ????????????????{??
77. ????????????????????progBar.setProgress(msg.arg1);//设置进度控件的当前进度为msg.arg1li