Concurrent - Executors - newCachedThreadPool()

原创转载请注明出处：http://agilestyle.iteye.com/blog/2343390

使用Executors的newCachedThreadPool()创建的是无界线程池，可以进行线程的自动回收。

所谓的“无界线程池”就是池中存放线程个数是理论上的Integer.MAX_VALUE最大值。

 

ExecutorTest1.java

package org.fool.java.concurrent.executor;

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

public class ExecutorTest1 {
    public static void main(String[] args) {
        ExecutorService executorService = Executors.newCachedThreadPool();

        executorService.execute(new Runnable() {
            @Override
            public void run() {
                try {
                    System.out.println("Runnable 1 begin " + System.currentTimeMillis());

                    Thread.sleep(1000);

                    System.out.println("Thread A");
                    System.out.println("Runnable 1 end " + System.currentTimeMillis());
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });

        executorService.execute(new Runnable() {
            @Override
            public void run() {
                try {
                    System.out.println("Runnable 2 begin " + System.currentTimeMillis());

                    Thread.sleep(1000);

                    System.out.println("Thread B");
                    System.out.println("Runnable 2 end " + System.currentTimeMillis());
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

Run

Note:

线程A和线程B机会是同一时间开始执行的，2个线程之间是异步执行的。

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ExecutorTest2.java

package org.fool.java.concurrent.executor;

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

public class ExecutorTest2 {
    public static void main(String[] args) {
        ExecutorService executorService = Executors.newCachedThreadPool();

        for(int i = 0; i < 5; i++) {
            executorService.execute(new Runnable() {
                @Override
                public void run() {
                    System.out.println("invoked!");
                }
            });
        }
    }
}

Run

复用线程对象

MyThread.java

package org.fool.java.concurrent.executor;

public class MyThread implements Runnable {

    private String name;

    public MyThread(String name) {
        this.name = name;
    }

    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName() + " name=" + name + " begin " + System.currentTimeMillis());
        System.out.println(Thread.currentThread().getName() + " name=" + name + " end " + System.currentTimeMillis());
    }
}

ExecutorTest3.java

package org.fool.java.concurrent.executor;

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

public class ExecutorTest3 {
    public static void main(String[] args) throws InterruptedException {
        ExecutorService executorService = Executors.newCachedThreadPool();

        for(int i = 0; i < 5; i++) {
            executorService.execute(new MyThread(String.valueOf(i + 1)));
        }

        Thread.sleep(1000);

        System.out.println();

        for(int i = 0; i < 5; i++) {
            executorService.execute(new MyThread(String.valueOf(i + 1)));
        }
    }
}

Run

 

使用newCachedThreadPool(ThreadFactory threadFactory)定制线程工厂

MyThreadFactory.java

package org.fool.java.concurrent.executor;

import java.util.concurrent.ThreadFactory;

public class MyThreadFactory implements ThreadFactory {
    @Override
    public Thread newThread(Runnable r) {
        Thread thread = new Thread(r);

        thread.setName("My Own Thread");

        return thread;
    }
}

ExecutorTest4.java

package org.fool.java.concurrent.executor;

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

public class ExecutorTest4 {
    public static void main(String[] args) throws InterruptedException {
        MyThreadFactory myThreadFactory = new MyThreadFactory();

        ExecutorService executorService = Executors.newCachedThreadPool(myThreadFactory);

        executorService.execute(new Runnable() {
            @Override
            public void run() {
                System.out.println(Thread.currentThread().getName() + " invoked...");
            }
        });
    }
}

Run