1.12.4　使用LockSupport类实现线程暂停与恢复

suspend()与resume()方法是过期作废的，若想实现同样的功能，也可以使用JDK并发包里提供的LockSupport类作为替代，效果是一样的。

创建测试项目park_unpark。

创建自定义线程类代码如下：

---

package mythread;

import java.util.concurrent.locks.LockSupport;

public class MyThread1 extends Thread {
    @Override
    public void run() {
        System.out.println("begin " + System.currentTimeMillis());
        LockSupport.park();
        System.out.println("  end " + System.currentTimeMillis());
    }
}

---

创建运行类代码如下：

---

package test;

import java.util.concurrent.locks.LockSupport;

import mythread.MyThread1;

public class Test1 {
    public static void main(String[] args) throws InterruptedException {
        MyThread1 mythread = new MyThread1();
        mythread.start();

        Thread.sleep(4000);
        LockSupport.unpark(mythread);
    }
}

---

运行结果如下：

---

begin 1616026920837
    end 1616026924836

---

park()方法的作用是将线程暂停，unpark()方法的作用是恢复线程的运行。

如果先执行unpark()再执行park()方法，则park()方法不会呈暂停的效果。

创建自定义线程类代码如下：

---

package mythread;

import java.util.concurrent.locks.LockSupport;

public class MyThread2 extends Thread {
    @Override
    public void run() {
        try {
            System.out.println("begin " + System.currentTimeMillis());
            Thread.sleep(5000);
            LockSupport.park();
            System.out.println("  end " + System.currentTimeMillis());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

---

运行类代码如下：

---

package test;

import java.util.concurrent.locks.LockSupport;

import mythread.MyThread2;

public class Test2 {
    public static void main(String[] args) throws InterruptedException {
        MyThread2 mythread = new MyThread2();
        mythread.start();

        Thread.sleep(2000);
        LockSupport.unpark(mythread);
    }
}

---

运行结果如下：

---

begin 1616027833016
    end 1616027838017

---