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();
  }
}