Java Callable并发编程模板

submit方法会产生Future对象，它用Callable返回结果的特定类型进行了参数化，可以用isDone()的方法来查询Future是否已经完成。当任务完成是，它具有一个结果，可以调用get()方法来获取该结果。

/**
* @Title: TaskWithResult.java
* @Package zeze
* @Description: TODO(用一句话描述该文件做什么)
* @author A18ccms A18ccms_gmail_com
* @date 2017年2月8日 上午10:51:26
* @version V1.0
*/
package zeze;

import java.util.ArrayList;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class CallableDemo {
    public static void main(String[] args) {
        ExecutorService exec = Executors.newCachedThreadPool();
        ArrayList<Future<String>> results = new ArrayList<Future<String>>();
        for (int i = 0; i < 10; i++) {
            results.add(exec.submit(new TaskWithResult(i)));
        }
        for (Future<String> fs : results) {
            try {
                System.out.println(fs.get());
            } catch (Exception e) {
                System.err.println(e);
            } finally {
                exec.shutdown();
            }
        }

    }
}

class TaskWithResult implements Callable<String> {

    private int id;

    public TaskWithResult(int id) {
        this.id = id;
    }

    @Override
    public String call() {
        return "result of TaskWithResult " + id;
    }

}

用isDone()的方法来查询Future是否已经完成

boolean isDone = false;
        while (!isDone) {
            logger.info(Thread.currentThread().getName() + " 线程是否结束?"+ runningFlag+"; 队列大小=" + nextDepthQueue.size());
            isDone = true;
            for (Future<Object> future : futureList) {
                if (!future.isDone()) {
                    isDone = false;
                    try {
                        Thread.sleep(3000);
                    } catch (InterruptedException e) {
                    }
                    break;
                }
            }
}

改进版：

package test;

import java.util.ArrayList;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

/***
 *
 * @ClassName: EbayMultiplyThreadCheck
 * @Description: TODO
 * @author zeze
 * @date 2017年2月16日 上午8:49:46
 *
 */
public class EbayMultiplyThreadCheck {
    public static void main(String[] args) {
        ExecutorService exec = Executors.newFixedThreadPool(10);
        ArrayList<Future<String>> results = new ArrayList<Future<String>>();

        for (int i = 0; i < 10; i++) {
            String email = "asd" + i + "@qq.com";
            results.add(exec.submit(new TaskWithResult(email)));
        }

        boolean isDone = false;
        while (!isDone) {
            isDone = true;
            for (Future<String> future : results) {
                if (!future.isDone()) {
                    isDone = false;
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                    }
                    break;
                }
            }
        }
        exec.shutdown();
    }
}

class TaskWithResult implements Callable<String> {

    private String email;

    public TaskWithResult(String email) {
        this.email = email;
    }

    @Override
    public String call() {
        System.out.println(email);
        return null;
    }

}

Runnable 实现：

/**
* @Title: RunnableDemo.java
* @Package zeze
* @Description: TODO(用一句话描述该文件做什么)
* @author A18ccms A18ccms_gmail_com
* @date 2017年3月13日 下午4:08:09
* @version V1.0
*/
package zeze;

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

import javafx.animation.Animation.Status;

/**
 * @ClassName: RunnableDemo
 * @Description: TODO
 * @author zeze
 * @date 2017年3月13日 下午4:08:09
 *
 */
public class RunnableDemo implements Runnable {

	protected int countDown = 10;
	private static int taskCount = 0;
	private final int id = taskCount++;

	public RunnableDemo() {
	}

	public RunnableDemo(int countDown) {
		this.countDown = countDown;
	}

	public String status() {
		return "#" + id + "(" + (countDown > 0 ? countDown : "LiftOff!") + ").";
	}

	@Override
	public void run() {
		while (countDown-- > 0) {
			System.out.print(status());
			Thread.yield();// 将CPU从一个线程转移给另一个线程
		}
	}

	public static void main(String[] args) {

		System.out.println("这个任务的run()不是单独的线程驱动，是在main()中直接调用");
		RunnableDemo launch = new RunnableDemo();
		launch.run();
		System.out.println();
		System.out.println("************************************");

		System.out.println("在新线程中启动任务");
		Thread thread = new Thread(new RunnableDemo());
		thread.start();
		System.out.println("Waiting for LiftOff");
		System.out.println("************************************");

		System.out.println("添加多个线程去驱动更多的任务");
		for (int i = 0; i < 5; i++) {
			new Thread(new RunnableDemo()).start();
		}
		System.out.println("Waiting for LiftOff");

		System.out.println("************************************");
		System.out.println("使用executor");
		ExecutorService exec = Executors.newCachedThreadPool();
		exec=Executors.newFixedThreadPool(5);
		for (int i = 0; i < 5; i++) {
			exec.execute(new RunnableDemo());
		}
		exec.shutdown();
	}

}