Java并发编程实例--6.线程的join方法_java 并发 join使用实例-优快云博客

本文通过两个具体的例子，展示了如何使用Java中的Thread类的join()方法实现线程间的同步。首先介绍了数据源加载和网络连接加载两个任务，并通过主线程等待这两个任务完成后再继续执行的方式，确保了资源初始化完毕后才开始其他操作。

有时我们需要等到某个线程执行完毕。例如，我可能有一个线程来初始化资源完毕然后其他线程才能开始执行。
谓词，我们可以使用Thread类的join()方法。

本例中，我们将学习使用这个方法。

DataSourcesLoader.java

package com.dylan.thread.ch1.c06;

import java.util.Date;
import java.util.concurrent.TimeUnit;

/**
 * @author xusucheng
 * @create 2018-04-25
 **/
public class DataSourcesLoader implements Runnable{
    @Override
    public void run() {
        System.out.printf("Beginning data sources loading: %s\n",new
                Date());
        try {
            TimeUnit.SECONDS.sleep(4);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.printf("Data sources loading has finished: %s\n",new Date());
    }
}

NetworkConnectionsLoader.java

package com.dylan.thread.ch1.c06;

import java.util.Date;
import java.util.concurrent.TimeUnit;

/**
 * @author xusucheng
 * @create 2018-04-25
 **/
public class NetworkConnectionsLoader implements Runnable {
    @Override
    public void run() {
        // Writes a message
        System.out.printf("Begining network connections loading: %s\n",new Date());
        // Sleep six seconds
        try {
            TimeUnit.SECONDS.sleep(6);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // Writes a message
        System.out.printf("Network connections loading has finished: %s\n",new Date());
    }
}

Main.java

package com.dylan.thread.ch1.c06;

import java.util.Date;

/**
 * @author xusucheng
 * @create 2018-04-25
 **/
public class Main {
    public static void main(String[] args) {
        DataSourcesLoader dsLoader = new DataSourcesLoader();
        Thread thread1 = new Thread(dsLoader,"DataSourceThread");
        NetworkConnectionsLoader ncLoader = new NetworkConnectionsLoader();
        Thread thread2 = new Thread(ncLoader,"NetworkConnectionLoader");
        thread1.start();
        thread2.start();
        try {
            thread1.join();
            thread2.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.printf("Main: Configuration has been loaded: %s\n",new Date());
    }
}

输出：

Beginning data sources loading: Wed Apr 25 23:11:50 CST 2018
Begining network connections loading: Wed Apr 25 23:11:50 CST 2018
Data sources loading has finished: Wed Apr 25 23:11:54 CST 2018
Network connections loading has finished: Wed Apr 25 23:11:56 CST 2018
Main: Configuration has been loaded: Wed Apr 25 23:11:56 CST 2018