Java线程池

Java线程池

Java多线程使用线程池效果更好, 目的如连接池.

第一个实例.

ThreadPool.java

package com.lichen.test; 

import java.util.concurrent.ArrayBlockingQueue; 
import java.util.concurrent.ThreadPoolExecutor; 
import java.util.concurrent.TimeUnit; 

public class ThreadPool { 

  private static int produceTaskSleepTime = 2; 
  private static int consumeTaskSleepTime = 2000; 
  private static int produceTaskMaxNumber = 10; 

  public static void main(String[] args) { 
    // 构造一个线程池 
     ThreadPoolExecutor threadPool = new ThreadPoolExecutor(2, 4, 3, 
         TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(3), 
        new ThreadPoolExecutor.DiscardOldestPolicy()); 

    for (int i = 1; i <= produceTaskMaxNumber; i++) { 
      try { 
        // 产生一个任务，并将其加入到线程池 
         String task = "task@ " + i; 
         System.out.println("put " + task); 
         threadPool.execute(new ThreadPoolTask(task)); 

        // 便于观察，等待一段时间 
         Thread.sleep(produceTaskSleepTime); 
       } catch (Exception e) { 
         e.printStackTrace(); 
       } 
     } 
   } 
}

 

ThreadPoolTask.java

package com.lichen.test; 

public class ThreadPoolTask implements Runnable { 
  // 保存任务所需要的数据 
  private Object threadPoolTaskData; 
  private static int consumeTaskSleepTime = 2000; 

   ThreadPoolTask(Object tasks) { 
    this.threadPoolTaskData = tasks; 
   } 

  public void run() { 
    // 处理一个任务，这里的处理方式太简单了，仅仅是一个打印语句 
     System.out.println("start .." + threadPoolTaskData); 
    try { 
      //便于观察，等待一段时间 
       Thread.sleep(consumeTaskSleepTime); 
     } catch (Exception e) { 
       e.printStackTrace(); 
     } 
     threadPoolTaskData = null; 
   } 

  public Object getTask() { 
    return this.threadPoolTaskData; 
   } 
}

 

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第二个实例.

TestThreadPool.java

package com.lichen.test; 

import java.util.concurrent.ExecutorService; 
import java.util.concurrent.Executors; 

public class TestThreadPool { 
  public static void main(String args[]) throws InterruptedException { 
    //只有2个线程 
     ExecutorService exec = Executors.newFixedThreadPool(2); 
    for (int index = 0; index < 100; index++) { 
       Runnable run = new Runnable() { 
        public void run() { 
          long time = (long) (Math.random() * 1000); 
           System.out.println("Sleeping " + time + "ms"); 
          try { 
             Thread.sleep(time); 
           } catch (InterruptedException e) { 
             e.printStackTrace(); 
           } 
         } 
       }; 
       exec.execute(run); 
     } // must shutdown 
     exec.shutdown(); 
   } 
}