/*目的：分析一下单例设计模式中，懒汉式与饿汉式在多线程中的不同！开发时我们一般选择饿汉式，因为它简单明了，多线程中不会出现安全问题！而饿汉式需要我们自己处理程序中存在的安全隐患，但是饿汉式的程序技术含量更高！
*/
/* class SinglePerson implements Runnable{private static SinglePerson ss = new SinglePerson("hjz", 22);//恶汉式private int age;private String name;private int count;private SinglePerson(String name, int age){this.age = age;this.name = name;}private SinglePerson(){age = 10;name = " ";}public static SinglePerson getInstance(){return ss;}public String getName(){return name;}public int getAge(){return age;}public void setIntroduceCount(){++count;}public int getIntroduceCount(){return count;}public synchronized void run(){ss.setIntroduceCount();try{Thread.sleep(20);}catch(InterruptedException e){}System.out.println("this is " + ss.getName() + " " + ss.getAge() + " 被介绍的次数是：" + ss.getIntroduceCount());}} */class SinglePerson implements Runnable{private static SinglePerson ss = null;//懒汉式private int age;private String name;private int count;private SinglePerson(String name, int age){this.age = age;this.name = name;count=0;}private SinglePerson(){age = 10;name = " ";}/*public static SinglePerson getInstance(){if(ss==null){//单例设计模式中，懒汉式在多线程中的缺憾啊！可能不能保证对象的唯一性try{Thread.sleep(10);}catch(InterruptedException e){}ss = new SinglePerson("hjz", 22);}return ss;}*//* public static synchronized SinglePerson getInstance(){//保证了对象的唯一性，也就是安全性保证了！但是每当调用该函数时if(ss==null){ //都要判断一下同步锁对象，降低了程序的效率！try{Thread.sleep(10);}catch(InterruptedException e){}ss = new SinglePerson("hjz", 22);}return ss;} */public static SinglePerson getInstance(){//这就是懒汉式的安全又效率的代码！if(ss==null){//这一句是必须判断的！synchronized(SinglePerson.class){//这一句只是其他的线程访问时判断if(ss==null){try{Thread.sleep(10);}catch(InterruptedException e){}ss = new SinglePerson("hjz", 22);}}}return ss;}public String getName(){return name;}public int getAge(){return age;}public void setIntroduceCount(){++count;}public int getIntroduceCount(){return count;}public synchronized void run(){ss.setIntroduceCount();System.out.println("this is " + ss.getName() + " " + ss.getAge() + " 被介绍的次数是：" + ss.getIntroduceCount());}
}class OtherThread extends Thread{public void run(){SinglePerson.getInstance().run();}
}public class Test{public static void main(String[] args){new OtherThread().start();new OtherThread().start();new OtherThread().start();new Thread(SinglePerson.getInstance()).start();}
}
)
)
