Singleton：---------
package cn.tools;public class Singleton { //饿汉模式(变种) /*private static Singleton singleton; static{ singleton = new Singleton(); System.out.println("static ===== "+singleton.toString()); } private Singleton(){} public static Singleton getInstance(){ System.out.println("getInstance==========="); return singleton; } public static void test(){ System.out.println("test======== " + singleton.toString()); }*/ //双重校验锁 /*private static Singleton singleton ; private Singleton(){} public static Singleton getInstance(String threadNo){ //T1 T2 T3 //T4 if(singleton == null){ //T1 T2 T3 System.out.println("singleton 1 ================== threadNo:"+threadNo); synchronized (Singleton.class) { //T2 T1 T3 System.out.println("singleton 2 ================== threadNo:"+threadNo); if(singleton == null){ //T2 System.out.println("singleton 3 ============== threadNo:"+threadNo); singleton = new Singleton(); } } } return singleton; }*/ //静态内部类 lazy loading private static Singleton singleton; private Singleton(){} private static class SingletonHelper{ private static final Singleton INSTANCE = new Singleton(); } public static Singleton getInstance(){ return SingletonHelper.INSTANCE; } public static void test(){ System.out.println("test===" + singleton.toString()); } }
TestSingleton：---------
package cn.tools;public class TestSingleton { public static void main(String[] args) { System.out.println("Singleton.getInstance() === " + Singleton.getInstance().toString()); //Singleton.test(); }}
ThreadDemo：---------
package cn.tools;public class ThreadDemo extends Thread { private String threadNo; public ThreadDemo(String _threadNo){ threadNo = _threadNo; } @Override public void run() {//线程开始执行 // TODO Auto-generated method stub super.run(); System.out.println("run ================ threadNo:"+threadNo); //Singleton.getInstance(threadNo); } public String getThreadNo() { return threadNo; } public void setThreadNo(String threadNo) { this.threadNo = threadNo; } }
TestThreadDemo：---------
package cn.tools;public class TestThreadDemo { public static void main(String[] args) { //for：主线程（获取cpu资源之后，瞬间生成n个子线程，n个并发） for(int i = 0; i < 4; i++){ //new 开辟子线程 start：调用run，运行子线程 new ThreadDemo("thread"+i).start(); if(i == 1){ try { Thread.sleep(1000); System.out.println("sleep====================="); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }}