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chenweijie
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添加单例相关的例子
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‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton1/MyObject.java

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package com.chen.api.util.thread.study.chapter6.singleton1;
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/**
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* 饿汉模式
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*
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* @author : chen weijie
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* @Date: 2018-05-21 23:31
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*/
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public class MyObject {
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private static MyObject myObject = new MyObject();
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private MyObject() {
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}
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public static MyObject getInstance() {
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//此代码版本为立即加载，此代码的缺点是不能有其他实例变量
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//因为getInstance()没有同步，所以有可能出现线程安全的问题
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return myObject;
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton1/MyThread.java

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package com.chen.api.util.thread.study.chapter6.singleton1;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:36
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*/
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public class MyThread extends Thread {
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@Override
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public void run() {
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System.out.println(MyObject.getInstance().hashCode());
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton1/Run.java

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package com.chen.api.util.thread.study.chapter6.singleton1;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:37
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*/
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public class Run {
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public static void main(String[] args) {
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MyThread myThreadA = new MyThread();
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MyThread myThreadB = new MyThread();
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MyThread myThreadC = new MyThread();
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myThreadA.start();
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myThreadB.start();
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myThreadC.start();
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton2/MyObject.java

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package com.chen.api.util.thread.study.chapter6.singleton2;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:38
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*/
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public class MyObject {
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private static MyObject myObject = null;
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private MyObject() {
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}
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//懒汉模式，在多线程的情况下会出现同步问题。
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public static MyObject getInstance() {
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try {
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if (myObject == null) {
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Thread.sleep(1000);
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myObject = new MyObject();
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}
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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return myObject;
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton2/MyThread.java

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package com.chen.api.util.thread.study.chapter6.singleton2;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:36
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*/
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public class MyThread extends Thread {
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@Override
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public void run() {
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System.out.println(MyObject.getInstance().hashCode());
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton2/Run.java

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package com.chen.api.util.thread.study.chapter6.singleton2;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:41
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*/
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public class Run {
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public static void main(String[] args) {
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MyThread myThread1 = new MyThread();
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MyThread myThread2 = new MyThread();
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MyThread myThread3 = new MyThread();
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myThread1.start();
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myThread2.start();
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myThread3.start();
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton3/MyObject.java

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package com.chen.api.util.thread.study.chapter6.singleton3;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:48
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*/
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public class MyObject {
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private static MyObject myObject = null;
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private MyObject() {
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}
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//整个方法上锁，同步方法的效率太低了
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synchronized public static MyObject getInstance() {
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try {
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if (myObject == null) {
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Thread.sleep(2000);
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myObject = new MyObject();
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}
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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return myObject;
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton3/MyThread.java

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package com.chen.api.util.thread.study.chapter6.singleton3;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:36
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*/
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public class MyThread extends Thread {
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@Override
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public void run() {
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System.out.println(MyObject.getInstance().hashCode());
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton3/Run.java

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package com.chen.api.util.thread.study.chapter6.singleton3;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:41
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*/
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public class Run {
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public static void main(String[] args) {
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MyThread myThread11 = new MyThread();
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MyThread myThread22 = new MyThread();
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MyThread myThread33 = new MyThread();
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myThread11.start();
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myThread22.start();
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myThread33.start();
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton4/MyObject.java

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package com.chen.api.util.thread.study.chapter6.singleton4;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:54
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*/
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public class MyObject {
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private static MyObject myObject = null;
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private MyObject() {
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}
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public static MyObject getInstance() {
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//同步代码块 getInstance方法中的所有代码都上锁，这样做也会降低运行效率
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synchronized (MyObject.class) {
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if (myObject == null) {
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myObject = new MyObject();
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}
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}
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return myObject;
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton4/MyThread.java

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package com.chen.api.util.thread.study.chapter6.singleton4;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:56
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*/
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public class MyThread extends Thread {
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@Override
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public void run() {
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System.out.println(MyObject.getInstance().hashCode());
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton4/Run.java

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package com.chen.api.util.thread.study.chapter6.singleton4;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:57
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*/
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public class Run {
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public static void main(String[] args) {
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MyThread myThread4 = new MyThread();
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MyThread myThread5 = new MyThread();
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MyThread myThread6 = new MyThread();
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myThread4.start();
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myThread5.start();
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myThread6.start();
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton5/MyObject.java

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package com.chen.api.util.thread.study.chapter6.singleton5;
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/**
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* @author : chen weijie
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* @Date: 2018-05-22 00:01
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*/
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public class MyObject {
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private static MyObject myObject = null;
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private MyObject() {
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}
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//虽然对实例化对象的关键代码进行了同步，从代码结构上看效率得到了提升，但是无法解决多线程安全的问题。
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//同时又多个线程访问if (myObject == null) ，得到的结果可能不一样。
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public static MyObject getInstance() {
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if (myObject == null) {
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synchronized (MyObject.class) {
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myObject = new MyObject();
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}
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}
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return myObject;
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton5/MyThread.java

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package com.chen.api.util.thread.study.chapter6.singleton5;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:56
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*/
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public class MyThread extends Thread {
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@Override
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public void run() {
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System.out.println(MyObject.getInstance().hashCode());
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton5/Run.java

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package com.chen.api.util.thread.study.chapter6.singleton5;
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/**
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* @author : chen weijie
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* @Date: 2018-05-21 23:57
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*/
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public class Run {
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public static void main(String[] args) {
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MyThread myThread4 = new MyThread();
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MyThread myThread5 = new MyThread();
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MyThread myThread6 = new MyThread();
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myThread4.start();
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myThread5.start();
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myThread6.start();
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton6/MyObject.java

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package com.chen.api.util.thread.study.chapter6.singleton6;
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/**
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* @author : chen weijie
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* @Date: 2018-05-22 00:14
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*/
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public class MyObject {
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private volatile static MyObject myObject = null;
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private MyObject() {
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}
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//使用DCL双检查锁机制，既保证了同步代码的异步执行，又保证了单例的效果。
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public static MyObject getInstance() {
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if (myObject == null) {
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synchronized (MyObject.class) {
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myObject = new MyObject();
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}
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}
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return myObject;
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton6/MyThread.java

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package com.chen.api.util.thread.study.chapter6.singleton6;
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/**
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* @author : chen weijie
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* @Date: 2018-05-22 00:15
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*/
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public class MyThread extends Thread {
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@Override
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public void run() {
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System.out.println(MyObject.getInstance().hashCode());
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}
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}

‎src/main/java/com/chen/api/util/thread/study/chapter6/singleton6/Run.java

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package com.chen.api.util.thread.study.chapter6.singleton6;
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/**
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* @author : chen weijie
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* @Date: 2018-05-22 00:16
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*/
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public class Run {
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public static void main(String[] args) {
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MyThread myThread8 = new MyThread();
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MyThread myThread9 = new MyThread();
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MyThread myThread0 = new MyThread();
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myThread0.start();
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myThread8.start();
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myThread9.start();
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}
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}

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