从头认识多线程-2.23 静态内部类的同步机制跟普通类相同

这一章节主要讨论静态内部类的同步机制跟普通类相同。

1.当同步方法的时候

package com.ray.deepintothread.ch02.topic_23;/** *  * @author RayLee * */public class SynchOfStaticInnerClass {static class InnerClass {private static int id = 0;public static synchronized void service_1() throws InterruptedException {for (int i = 0; i < 5; i++) {System.out.println(Thread.currentThread().getName() + " id:" + id++);Thread.sleep(50);}}public static synchronized void service_2() throws InterruptedException {for (int i = 0; i < 5; i++) {System.out.println(Thread.currentThread().getName() + " id:" + id++);Thread.sleep(100);}}}public static void main(String[] args) {Thread thread = new Thread(new Runnable() {public void run() {try {InnerClass.service_1();} catch (InterruptedException e) {e.printStackTrace();}}});thread.start();Thread thread2 = new Thread(new Runnable() {public void run() {try {InnerClass.service_2();} catch (InterruptedException e) {e.printStackTrace();}}});thread2.start();}}

输出：

Thread-0 id:0
Thread-0 id:1
Thread-0 id:2
Thread-0 id:3
Thread-0 id:4
Thread-1 id:5
Thread-1 id:6
Thread-1 id:7
Thread-1 id:8
Thread-1 id:9

2.当同步代码块的时候

package com.ray.deepintothread.ch02.topic_23;/** *  * @author RayLee * */public class SynchOfStaticInnerClass2 {static class InnerClass {private static int id = 0;private static Object object = new Object();public static void service_1() throws InterruptedException {synchronized (object) {for (int i = 0; i < 5; i++) {System.out.println(Thread.currentThread().getName() + " id:" + id++);Thread.sleep(50);}}}public static void service_2() throws InterruptedException {synchronized (object) {for (int i = 0; i < 5; i++) {System.out.println(Thread.currentThread().getName() + " id:" + id++);Thread.sleep(100);}}}}public static void main(String[] args) {Thread thread = new Thread(new Runnable() {public void run() {try {InnerClass.service_1();} catch (InterruptedException e) {e.printStackTrace();}}});thread.start();Thread thread2 = new Thread(new Runnable() {public void run() {try {InnerClass.service_2();} catch (InterruptedException e) {e.printStackTrace();}}});thread2.start();}}

输出：

Thread-0 id:0
Thread-0 id:1
Thread-0 id:2
Thread-0 id:3
Thread-0 id:4
Thread-1 id:5
Thread-1 id:6
Thread-1 id:7
Thread-1 id:8
Thread-1 id:9

上面的两种方式都是可以实现同步机制，使得数据保持一致，不会出现脏读

3.当同步方法与同步代码块同时出现的时候

package com.ray.deepintothread.ch02.topic_23;/** *  * @author RayLee * */public class SynchOfStaticInnerClass3 {static class InnerClass {private static int id = 0;private static Object object = new Object();public static void service_1() throws InterruptedException {synchronized (object) {for (int i = 0; i < 5; i++) {System.out.println(Thread.currentThread().getName() + " id:" + id++);Thread.sleep(50);}}}public static synchronized void service_2() throws InterruptedException {for (int i = 0; i < 5; i++) {System.out.println(Thread.currentThread().getName() + " id:" + id++);Thread.sleep(100);}}}public static void main(String[] args) {Thread thread = new Thread(new Runnable() {public void run() {try {InnerClass.service_1();} catch (InterruptedException e) {e.printStackTrace();}}});thread.start();Thread thread2 = new Thread(new Runnable() {public void run() {try {InnerClass.service_2();} catch (InterruptedException e) {e.printStackTrace();}}});thread2.start();}}

输出：

Thread-0 id:0
Thread-1 id:0
Thread-0 id:1
Thread-0 id:2
Thread-1 id:3
Thread-0 id:4
Thread-0 id:5
Thread-1 id:6
Thread-1 id:7
Thread-1 id:8

从输出可以看见，数据不同步，出现脏读

4.当使用不同监视器来同步代码块的时候

package com.ray.deepintothread.ch02.topic_23;/** *  * @author RayLee * */public class SynchOfStaticInnerClass4 {static class InnerClass {private static int id = 0;private static Object object1 = new Object();private static Object object2 = new Object();public static void service_1() throws InterruptedException {synchronized (object1) {for (int i = 0; i < 5; i++) {System.out.println(Thread.currentThread().getName() + " id:" + id++);Thread.sleep(50);}}}public static synchronized void service_2() throws InterruptedException {synchronized (object2) {for (int i = 0; i < 5; i++) {System.out.println(Thread.currentThread().getName() + " id:" + id++);Thread.sleep(100);}}}}public static void main(String[] args) {Thread thread = new Thread(new Runnable() {public void run() {try {InnerClass.service_1();} catch (InterruptedException e) {e.printStackTrace();}}});thread.start();Thread thread2 = new Thread(new Runnable() {public void run() {try {InnerClass.service_2();} catch (InterruptedException e) {e.printStackTrace();}}});thread2.start();}}

输出：

Thread-1 id:0
Thread-0 id:0
Thread-0 id:1
Thread-0 id:2
Thread-1 id:3
Thread-0 id:4
Thread-0 id:5
Thread-1 id:6
Thread-1 id:7
Thread-1 id:8

上面的两种情况就会出现数据不同步的现象。

总结：这一章节主要展示静态内部类的同步机制跟普通类相同。

这一章节就到这里，谢谢

------------------------------------------------------------------------------------

我的github：https://github.com/raylee2015/DeepIntoThread

目录：http://blog.csdn.net/raylee2007/article/details/51204573