浅谈Android中线程池的管理

// 这里开启一个子线程进行耗时操作
 new Thread() {
  @Override
  public void run() {
   .......
   Message mMessage = new Message();
   mMessage.what = 1;
   //在这里发送给消息队列
   mMyHandler.sendMessage(mMessage);
   }
  }.start();
 /**
  * 这里就是处理的地方 通过msg.what进行处理分辨
  */
 class MyHandler extends Handler{
  @Override
  public void handleMessage(Message msg) {
   super.handleMessage(msg);
   switch (msg.what){
   //取出对应的消息进行处理
    ........
   }
  }
 }

# ActivityThread.main
public static void main(String[] args) {
  //省略代码。。。。。
  
  //在这里创建了一个消息队列！
  Looper.prepareMainLooper();

  ActivityThread thread = new ActivityThread();
  thread.attach(false);

  if (sMainThreadHandler == null) {
   sMainThreadHandler = thread.getHandler();
  }

  //这句我也没有看懂 这不是一直都不会执行的么
  if (false) {
   Looper.myLooper().setMessageLogging(new
     LogPrinter(Log.DEBUG, "ActivityThread"));
  }

  Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
  //消息队列跑起来了！
  Looper.loop();

  throw new RuntimeException("Main thread loop unexpectedly exited");
 }

public Handler(Callback callback, boolean async) {
  mLooper = Looper.myLooper();
  //注意看这里抛出的异常 如果这里mLooper==null
  if (mLooper == null) {
   throw new RuntimeException(
    "Can't create handler inside thread that has not called Looper.prepare()");
  }
  //获取消息队列
  mQueue = mLooper.mQueue;
  mCallback = callback;
  mAsynchrOnous= async;
 }

new Thread() {
  Handler mHandler = null;
  @Override
  public void run() {
   //在这里获取
   Looper.prepare();
   mHandler = new Handler();
   //在这里启动
   Looper.loop();
  }
 }.start();

new Thread() {
   @Override
   public void run() {
    doing.....
   }
  }.start();

new Thread(new Runnable() {
   @Override
   public void run() {
    doing.....
   }
  }).start();

/**
 * ================================================
 * 作 者：夏沐尧 Github地址：https://github.com/XiaMuYaoDQX
 * 版 本：1.0
 * 创建日期： 2018/1/10
 * 描 述：
 * 修订历史：
 * ================================================
 */
class FutureDemo {
 //创建一个单例线程
 static ExecutorService mExecutor = Executors.newSingleThreadScheduledExecutor();

 public static void main(String[] args) throws ExecutionException, InterruptedException {
  ftureWithRunnable();
  ftureWithCallable();
  ftureTask();
 }

 /**
  * 没有指定返回值，所以返回的是null,向线程池中提交的是Runnable
  *
  * @throws ExecutionException
  * @throws InterruptedException
  */
 private static void ftureWithRunnable() throws ExecutionException, InterruptedException {
  Future<&＃63;> result1 = mExecutor.submit(new Runnable() {
   @Override
   public void run() {
    fibc(20);
    System.out.println(Thread.currentThread().getName());
   }
  });
  System.out.println("Runnable" + result1.get());
 }

 /**
  * 提交了Callable，有返回值，可以获取阻塞线程获取到数值
  *
  * @throws ExecutionException
  * @throws InterruptedException
  */
 private static void ftureWithCallable() throws ExecutionException, InterruptedException {
  Future result2 = mExecutor.submit(new Callable() {
   @Override
   public Integer call() throws Exception {
    System.out.println(Thread.currentThread().getName());
    return fibc(20);
   }
  });
  System.out.println("Callable" + result2.get());
 }

 /**
  * 提交的futureTask对象
  * @throws ExecutionException
  * @throws InterruptedException
  */
 private static void ftureTask() throws ExecutionException, InterruptedException {
  FutureTask futureTask = new FutureTask(new Callable() {
   @Override
   public Integer call() throws Exception {
    System.out.println(Thread.currentThread().getName());
    return fibc(20);
   }
  });
  mExecutor.submit(futureTask);
  System.out.println("futureTask" + futureTask.get());

 }

 private static int fibc(int num) {
  if (num == 0) {
   return 0;
  }
  if (num == 1) {
   return 1;
  }
  return fibc(num - 1) + fibc(num - 2);
 }
}

public class ThreadPoolExecutorTest { 
 public static void main(String[] args) { 
 ExecutorService cachedThreadPool = Executors.newCachedThreadPool(); 
 for (int i = 0; i <10; i++) { 
 final int index = i; 
 try { 
 Thread.sleep(index * 1000); 
 } catch (InterruptedException e) { 
 e.printStackTrace(); 
 } 
 cachedThreadPool.execute(new Runnable() { 
 public void run() { 
  System.out.println(index); 
 } 
 }); 
 } 
 } 
} 

public class ThreadPoolExecutorTest { 
 public static void main(String[] args) { 
 ExecutorService fixedThreadPool = Executors.newFixedThreadPool(3); 
 for (int i = 0; i <10; i++) { 
 final int index = i; 
 fixedThreadPool.execute(new Runnable() { 
 public void run() { 
  try { 
  System.out.println(index); 
  Thread.sleep(2000); 
  } catch (InterruptedException e) { 
  e.printStackTrace(); 
  } 
 } 
 }); 
 } 
 } 
} 

public class ThreadPoolExecutorTest { 
 public static void main(String[] args) { 
 ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5); 
 scheduledThreadPool.schedule(new Runnable() { 
 public void run() { 
 System.out.println("delay 3 seconds"); 
 } 
 }, 3, TimeUnit.SECONDS); 
 } 
} 

public class ThreadPoolExecutorTest { 
 public static void main(String[] args) { 
 ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5); 
 scheduledThreadPool.scheduleAtFixedRate(new Runnable() { 
 public void run() { 
 System.out.println("delay 1 seconds, and excute every 3 seconds"); 
 } 
 }, 1, 3, TimeUnit.SECONDS); 
 } 
} 

public class ThreadPoolExecutorTest { 
 public static void main(String[] args) { 
 ExecutorService singleThreadExecutor = Executors.newSingleThreadExecutor(); 
 for (int i = 0; i <10; i++) { 
 final int index = i; 
 singleThreadExecutor.execute(new Runnable() { 
 public void run() { 
  try { 
  System.out.println(index); 
  Thread.sleep(2000); 
  } catch (InterruptedException e) { 
  e.printStackTrace(); 
  } 
 } 
 }); 
 } 
 } 
}