Android-初識Handler-子線程異步更新UI

簡單的例子：子線程異步的更新UI，同時不影響主線程的操作本身界面的操作
下面是main.xml配置文件

1. <?xml version="1.0" encoding="utf-8"?>
2. <LinearLayout xmlns:Android="http://schemas.android.com/apk/res/android"
3. android:layout_width="fill_parent"
4. android:layout_height="fill_parent"
5. android:orientation="vertical" >
7. <Button
8. android:id="@+id/btnFirst"
9. android:layout_width="fill_parent"
10. android:layout_height="wrap_content"
11. android:text="按鈕1" >
12. </Button>
14. <Button
15. android:id="@+id/btnSecond"
16. android:layout_width="fill_parent"
17. android:layout_height="wrap_content"
18. android:text="按鈕2" >
19. </Button>
21. </LinearLayout>

代碼：

1. package com.liujin.game;
3. import android.app.Activity;
4. import android.os.Bundle;
5. import android.os.Handler;
6. import android.os.Looper;
7. import android.os.Message;
8. import android.view.View;
9. import android.view.View.OnClickListener;
10. import android.widget.Button;
12. public class TestHandlerImage extends Activity implements OnClickListener {
13. private Button btnFirst, btnSecond;
14. public void onCreate(Bundle savedInstanceState) {
15. super.onCreate(savedInstanceState);
16. setContentView(R.layout.main);
17. btnFirst = (Button) this.findViewById(R.id.btnFirst);//得到按鈕
18. btnSecond = (Button) this.findViewById(R.id.btnSecond);
19. btnFirst.setOnClickListener(this);//設置監控
20. btnSecond.setOnClickListener(this);
21. MyThread myThread = new MyThread();//開啟子線程
22. myThread.start();
24. }
26. @Override
27. public void onClick(View view) {
28. switch (view.getId()) {
29. case R.id.btnFirst:
30. btnFirst.setText("我點擊按鈕1");
31. btnSecond.setText("等待點擊");
32. break;
33. case R.id.btnSecond:
34. btnFirst.setText("等待點擊");
35. btnSecond.setText("我點擊按鈕2");
36. break;
37. }
38. }
40. class MyThread extends Thread {
41. TitleEventHandler handler;
42. public int sleepTime=1000;
43. public int Interval=0;
44. public void run() {
45. Looper mainLooper = Looper.getMainLooper();//得到主線程的Looper，每一個Activity都默認自帶一個Looper看上一篇的源碼
46. handler = new TitleEventHandler(mainLooper);
47. handler.removeMessages(0);
48. Message msg = null;
49. Long start,end;
50. int time = 15;
51. while (true) {//下面的代碼很簡單就是定時的每過一秒發送一個消息給主線程
52. try {
53. time--;
54. start=System.currentTimeMillis();
55. msg = handler.obtainMessage(1, 1, 1, "當前還剩" + (time + 1)+ "秒");
56. handler.sendMessage(msg);//發送消息
57. end=System.currentTimeMillis();
58. Interval=(int) (end-start);
59. if(Interval<sleepTime){//定時睡覺疫苗
60. Thread.sleep(sleepTime-Interval);
61. }
62. } catch (InterruptedException e) {
63. }
64. }
65. }
66. }
68. class TitleEventHandler extends Handler {
69. public TitleEventHandler() {
70. super();
71. }
73. public TitleEventHandler(Looper looper) {
74. super(looper);
75. }
77. @Override
78. public void handleMessage(Message msg) {
79. super.handleMessage(msg);
80. setTitle((String) msg.obj);
81. }
82. }
83. }

下面是main.xml配置文件