ThreadLocal

Java中的ThreadLocal类允许我们创建只能被同一个线程读写的变量。

因此，如果一段代码含有一个ThreadLocal变量的引用，即使两个线程同时执行这段代码，它们也无法访问到对方的ThreadLocal变量

 

1. public class Session{  
2.     private  static ThreadLocal<Session> thread_local=new ThreadLocal<Session>();  
3.     private Session() {  
4.     }  
5.     public static Session getInstance() {  
6.         if(thread_local.get()==null){  
7.             thread_local.set(new Session());  
8.         }  
9.         return thread_local.get();  
10.     }  
11. }  

 

public class Test {
    public static void main(String[] args) throws NoSuchMethodException,
            SecurityException, InstantiationException, IllegalAccessException,
            IllegalArgumentException, InvocationTargetException {
        final Session session1=Session.getInstance();
        Session session2=Session.getInstance();
        System.out.println(session1==session2);

        new Thread(){
            public void run() {
                Session session=Session.getInstance();
                System.out.println(session==session1);
            };
        }.start();
    }

 

true

false