synchronized锁重入

image.png

  /**
 * @Description TODO
 * @Author "zhouhai"
 * @Date2018/10/721:21
 **/
public class SyncDubbo1 {

    public synchronized void method1() {
        System.out.println("method1..");
        method2();
    }

    public synchronized void method2() {
        System.out.println("method2..");
        method3();
    }

    public synchronized void method3() {
        System.out.println("method3..");
    }


    public static void main(String[] args) {
        final SyncDubbo1 sd = new SyncDubbo1();

        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                sd.method1();
            }
        });

        t1.start();

    }
}

method1..
method2..
method3..
重入锁

/**
 * @Description TODO
 * @Author "zhouhai"
 * @Date2018/10/720:22
 **/
public class SyncDubbo {

    static class Main{

        public int i = 10;

        public synchronized void operationSup() {
            try {
                i--;
                System.out.println("Main print i = "+i);
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }

    static  class Sub extends  Main {
        public synchronized void operationSub() {
            try {
                while (i > 0) {
                    i--;
                    System.out.println("Sub print i = "+i);
                    Thread.sleep(100);
                    this.operationSup();
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {

        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                Sub sub = new Sub();

                sub.operationSub();
            }
        });

        t1.start();

    }
}

Sub print i = 9
Main print i = 8
Sub print i = 7
Main print i = 6
Sub print i = 5
Main print i = 4
Sub print i = 3
Main print i = 2
Sub print i = 1
Main print i = 0

有继承关系的synchronized并不影响其使用,父子类一起同步保证其线程安全

/**
 * @Description TODO
 * @Author "zhouhai"
 * @Date2018/10/721:03
 **/
public class SyncException {

    private int i = 0;

    public synchronized void operation() {
        while (true) {
            try {
                i++;
                Thread.sleep(200);
                System.out.println(Thread.currentThread().getName() + ",i=" + i);
                if (i == 10) {
                    Integer.parseInt("a");
                }
            } catch (Exception e) {
                e.printStackTrace();
                System.out.println("log info i = " + i);
            }
        }
    }

    public static void main(String[] args) {
        final SyncException se = new SyncException();

        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                se.operation();
            }
        }, "t1");

        t1.start();
    }


}

t1,i=1
t1,i=2
t1,i=3
t1,i=4
t1,i=5
t1,i=6
t1,i=7
t1,i=8
t1,i=9
t1,i=10
log info i = 10
java.lang.NumberFormatException: For input string: "a"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:580)
at java.lang.Integer.parseInt(Integer.java:615)
at SyncException.operation(SyncException.java:17)
at SyncException$1.run(SyncException.java:32)
at java.lang.Thread.run(Thread.java:745)
t1,i=11
t1,i=12
t1,i=13
t1,i=14

同步锁遇到异常直接释放锁