线程范围内的共享数据

ThreadLocal 实现线程范围的共享变量

线程范围内的变量，在线程内共享，在线程外独立

特殊的类：ThreadLocal类，就相当于map

一个ThreadLocal代表一个变量，故其中只能放一个数据

若需要里那个变量要线程内共享，则要定义两个ThreadLocal对象

private static ThreadLocal<Integer> x=new ThreadLocal<Integer>();
     public static void main(String[] args) {
        for (int i = 0; i < 2; i++) {
            new Thread(new Runnable() {
                public void run() {
                    int data = new Random().nextInt();
                    System.out.println(Thread.currentThread().getName()
                            + " has put data: " + data);
                    x.set(data);
                    new A().get();
                    new B().get();
                }
            }).start();
        }
    }

    static class A {
        public void get() {
            int data =x.get();
            System.out.println("A from " + Thread.currentThread().getName()
                    + " get data: " + data);
        }
    }
    static class B {
        public void get() {
            int data =x.get();
            System.out.println("B from " + Thread.currentThread().getName()
                    + " get data: " + data);
        }
    }