多线程编程-synchronized与锁

静态同步synchronized方法与非静态同步synchronized方法的锁
1、静态同步synchronized方法锁是本类的字节码文件锁
2、非静态同步synchronized方法的锁是this锁
syA、syB、syC、syD、syE五个方法

package com.example.demo.my_synchronized;
/**
 * @ Author     ：lzy
 * @ Date       ：Created in  2019/8/5 15:00
 * @ Description：
 */
public class Synchronized {
    public synchronized void syA(){
        System.out.println("this is syA");
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    public void syB(){
        synchronized (this){
            System.out.println("this is syB");
        }
    }
    public void syC(){
        String s="1";
        synchronized (s){
            System.out.println("this is syC");
        }
    }
    public void syD(){
        synchronized (Synchronized.class){
            System.out.println("this is syD");
            try {
                Thread.sleep(6000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    public synchronized static void syE(){
        System.out.println("this is syE");
    }
}

定义

  package com.example.demo.my_synchronized;
    /**
     * @ Author     ：lzy
     * @ Date       ：Created in  2019/8/5 15:07
     * @ Description：
     */
    public class SynchronizedMain {
        public static void main(String[] args) {
            Synchronized aSynchronized = new Synchronized();
            new Thread(new Runnable() {
                @Override
                public void run() {
                    aSynchronized.syA();
                }
            }).start();
            new Thread(new Runnable() {
                @Override
                public void run() {
                    aSynchronized.syB();
                }
            }).start();
            new Thread(new Runnable() {
                @Override
                public void run() {
                    aSynchronized.syC();
                }
            }).start();
            new Thread(new Runnable() {
                @Override
                public void run() {
                    aSynchronized.syD();
                }
            }).start();
            new Thread(new Runnable() {
                @Override
                public void run() {
                    aSynchronized.syE();
                }
            }).start();
        }
    }

运行结果

运行结果–比较syA、syB、syC运行时间，syA与syC快速出现，而syB是三秒之后出现，证明执行syA时睡眠三秒是，syB等待，等syA释放锁之后syB执行，所以非静态同步方法锁就是this锁。

运行结果–比较syD、syE，当syD释放锁之后syE执行，所以静态同步方法是类字节码锁