The document discusses the relationship between Handlers and Threads in Android. It explains that Runnable is a task that can be executed, Thread is a process that can run tasks, and Handler allows communication between threads by sending Message objects. The document also discusses how to create HandlerThreads, which are persistent thread classes in Android, and how to use runOnUiThread() to run tasks on the main UI thread from other threads.

1. Handler和Thread的關係
Johnny Sung
2013/08/22
多執行緒-
1
Thursday, August 22, 13

2. 關於我
• I'm an Android developer.
Also learning iOS development.
• Information Management
in Shih Hsin University
• 相關作品：
• Good! 愛點兒
• 世新廣播電台
• 主要語⾔言：
• Obj-C / Java / C# / PHP
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3. Good! 愛點兒
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4. 世新廣播電台
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5. 5
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6. 6
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7. 問題
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8. 8
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9. 9
ANR = Activity Not Responding
http://developer.android.com/training/articles/perf-anr.html
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10. MultiThreading 多執行緒
•Runnable
•Thread
•Handler
•Message
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11. 11
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12. Runnable
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13. 13
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14. class GetWebPicture implements Runnable
{
@Override
public void run()
{
// ........
}
}
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15. Thread
顧名思義，它就叫執⾏行緒
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16. 16
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17. Thread又有分二種
•單次型 Thread(Java原有的)
•常駐型 HandlerThread (Android特有的)
常駐型 HandlerThread留到後⾯面再說
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18. 18
new Thread(new Runnable()
{
@Override
public void run()
{
// ......
}
}).start();
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19. new Thread()
{
@Override
public void run()
{
// ....
}
}.start();
19
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20. Main Thread(UI Thread)20
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21. Main Thread(UI Thread)20
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22. new Thread()
{
@Override
public void run()
{
// ....
}
}.start();
Thread1
Main Thread(UI Thread)20
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23. new Thread()
{
@Override
public void run()
{
// ....
}
}.start();
Thread1
Main Thread(UI Thread)20
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24. new Thread()
{
@Override
public void run()
{
// ....
}
}.start();
Thread1
Main Thread(UI Thread)
runOnUiThread(new Runnable()
{
public void run()
{
// ......
}
});
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25. new Thread()
{
@Override
public void run()
{
// ....
}
}.start();
Thread1
Main Thread(UI Thread)
runOnUiThread(new Runnable()
{
public void run()
{
// ......
}
});
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26. HandlerThread
是⼀一種常駐型的Thread
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27. mThread = new HandlerThread("name");
mThread.start();
mThreadHandler = new Handler(mThread.getLooper())
{
public void handleMessage(android.os.Message msg)
{
switch (msg.what)
{
case START_SERVER:
// .....
break;
case STOP_SERVER:
// .....
break;
default:
break;
}
}
};
在onCreate()之中
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28. 在onDestroy()之中
if (mThread != null)
mThread.quit();
寫在Service裡⾯面不錯⽤用
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29. Main Thread(UI Thread)
onCreate()
onResume()
onPause()
onDestroy()
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30. HandlerThread1
Main Thread(UI Thread)
onCreate()
onResume()
onPause()
onDestroy()
mThread = new HandlerThread("name");
mThread.start();
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31. HandlerThread1
Main Thread(UI Thread)
onCreate()
onResume()
onPause()
onDestroy()
mThread = new HandlerThread("name");
mThread.start();
if (mThread != null)
mThread.quit();
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32. HandlerThread1
Main Thread(UI Thread)
onCreate()
onResume()
onPause()
onDestroy()
mThread = new HandlerThread("name");
mThread.start();
if (mThread != null)
mThread.quit();
(Idle)
(Running)
(Running)
(Idle)
(Idle)
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33. Handler
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34. 26
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35. Handler mHandler = new Handler()
{
@Override
public void handleMessage(Message msg)
{
switch (msg.what)
{
case 0:
// .......
break;
case 1:
// .......
break;
case 2:
// .......
break;
default:
break;
}
}
};
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36. Message
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37. Message就是要一言以蔽之
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38. 用一個值 (一句話)
代表一堆事情(Runnable)
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39. 31
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40. obtainMessage(int what);
obtainMessage(int what, int arg1, int arg2);
obtainMessage(int what, int arg1, int arg2, Object obj);
obtainMessage(int what, Object obj);
發訊息
記得加上.sendToTarget()才會發送
sendEmptyMessage(int what)
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41. http://developer.android.com/reference/android/os/Handler.html
其他常用的Method
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42. 我只想寫個小東西
Message & Handler 方式對我來說太複雜了
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43. 有沒有更快的方法？
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44. 有!
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45. runOnUiThread()
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46. runOnUiThread(new Runnable()
{
public void run()
{
// ......
}
});
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47. 讓我們看一下原始碼
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48. https://github.com/android/platform_frameworks_base/blob/master/core/java/android/app/Activity.java
// Reference from Activity.java
/**
* Runs the specified action on the UI thread. If the current thread is the
* UI thread, then the action is executed immediately. If the current thread
* is not the UI thread, the action is posted to the event queue of the UI
* thread.
*
* @param action
* the action to run on the UI thread
*/
public final void runOnUiThread(Runnable action)
{
if (Thread.currentThread() != mUiThread)
{
mHandler.post(action);
} else
{
action.run();
}
}
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49. 41
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50. Q & A
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51. Follow me on Blog
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52. Follow me on Facebook
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