Java7并发编程实战（一） 线程的等待

试想一个情景，有两个线程同时工作，还有主线程，一个线程负责初始化网络，一个线程负责初始化资源，然后需要两个线程都执行完毕后，才能执行主线程

　　首先创建一个初始化资源的线程

　　

public class DataSourcesLoader implements Runnable {

    /**
     * Main method of the class
     */
    @Override
    public void run() {

        // Writes a messsage
        System.out.printf("Begining data sources loading: %s\n",new Date());
        // Sleeps four seconds
        try {
            TimeUnit.SECONDS.sleep(4);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // Writes a message
        System.out.printf("Data sources loading has finished: %s\n",new Date());
    }
}

　　

　　然后创建一个初始化网络的线程

　　

public class NetworkConnectionsLoader implements Runnable {

    /**
     * Main method of the class
     */
    @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());
    }
}

　　

　　通过TimeUnit.SECONDS.sleep()方法; 进行休眠，

　　然后主线程执行，通过join方法，当一个线程对象的join方法被调用时，调用他的线程将会被挂起，知道这个线程来完成这些初始化任务，我们在主线程分别调用两个Thread的join方法，那么主线程会等到两个线程都执行完毕才会执行下去。

　　

public class Main {

    /**
     * Main method of the class. Create and star two initialization tasks
     * and wait for their finish
     * @param args
     */
    public static void main(String[] args) {

        // Creates and starts a DataSourceLoader runnable object
        DataSourcesLoader dsLoader = new DataSourcesLoader();
        Thread thread1 = new Thread(dsLoader,"DataSourceThread");
        thread1.start();

        // Creates and starts a NetworkConnectionsLoader runnable object
        NetworkConnectionsLoader ncLoader = new NetworkConnectionsLoader();
        Thread thread2 = new Thread(ncLoader,"NetworkConnectionLoader");
        thread2.start();

        // Wait for the finalization of the two threads
        try {
            thread1.join();
            thread2.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        // Waits a message
        System.out.printf("Main: Configuration has been loaded: %s\n",new Date());
    }
}