2.2.9静态方法同步与实例方法同步

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package cha02.execise23;/** * Created by sunyifeng on 17/9/27. */public class Service {    // 静态方法A    synchronized public static void printA() {        try {            System.out.println("进入方法printA，线程名称:" + Thread.currentThread().getName() + ",当前时间" + System.currentTimeMillis());            Thread.sleep(5000);            System.out.println("离开方法printA，线程名称:" + Thread.currentThread().getName() + ",当前时间" + System.currentTimeMillis());        } catch (InterruptedException e) {            e.printStackTrace();        }    }    // 静态方法B    synchronized public static void printB() {        System.out.println("进入方法printB，线程名称:" + Thread.currentThread().getName() + ",当前时间" + System.currentTimeMillis());        System.out.println("离开方法printB，线程名称:" + Thread.currentThread().getName() + ",当前时间" + System.currentTimeMillis());    }    // 实例方法C    synchronized public void printC() {        System.out.println("进入方法printC，线程名称:" + Thread.currentThread().getName() + ",当前时间" + System.currentTimeMillis());        System.out.println("离开方法printC，线程名称:" + Thread.currentThread().getName() + ",当前时间" + System.currentTimeMillis());    }}

package cha02.execise23;/** * Created by sunyifeng on 17/9/27. */public class ThreadA extends Thread {    private Service service;    public ThreadA(Service service) {        super();        this.service = service;    }    @Override    public void run(){        service.printA(); //    }}

package cha02.execise23;/** * Created by sunyifeng on 17/9/27. */public class ThreadB extends Thread {    private Service service;    public ThreadB(Service service) {        super();        this.service = service;    }    @Override    public void run() {        service.printB();//    }}

package cha02.execise23;/** * Created by sunyifeng on 17/9/27. */public class ThreadC extends Thread {    private Service service;    public ThreadC(Service service) {        super();        this.service = service;    }    @Override    public void run() {        service.printC(); //    }}

package cha02.execise23;/** * Created by sunyifeng on 17/9/27. */public class Run {    public static void main(String[] args) {        Service service = new Service();        //        ThreadA threadA = new ThreadA(service);        threadA.setName("A");        threadA.start();        //        ThreadB threadB = new ThreadB(service);        threadB.setName("B");        threadB.start();        //        ThreadC threadC = new ThreadC(service);        threadC.setName("C");        threadC.start();    }}

运行结果：

进入方法printA，线程名称:A,当前时间1507737435167
进入方法printC，线程名称:C,当前时间1507737435169
离开方法printC，线程名称:C,当前时间1507737435170
离开方法printA，线程名称:A,当前时间1507737440171
进入方法printB，线程名称:B,当前时间1507737440171
离开方法printB，线程名称:B,当前时间1507737440172

程序分析：

1、三个线程是异步执行的，线程A、线程B同步执行，线程C异步执行；

2、线程A、线程B持有的是class锁，线程C持有的是对象锁。

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