ThreadLocal 例子

/**
 * 一个ThreadLocal代表一个变量，故其中里只能放一个数据，有两个变量都要线程内共享，则要定义两个ThreadLocal。
 */
public class ThreadLocalTest {

    private static ThreadLocal<Integer> threadData = 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);
                    threadData.set(data);
                    new A().get();
                    new B().get();
                }
            }).start();
        }
    }

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

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

输出结果：

Thread-1 has put data :-1978178521
Thread-0 has put data :-227790491
A from Thread-0 get data: -227790491
A from Thread-1 get data: -1978178521
B from Thread-0 get data: -227790491
B from Thread-1 get data: -1978178521