Threadlocal能够为每个线程分配一份单独的副本，使的线程与线程之间能够独立的访问各自副本。Threadlocal 内部维护一个Map，key为线程的名字，value为对应操作的副本。

/**

 * Created by majun on 16/3/23.

 */

public class ThreadLocalTest {

    /*

    Threadlocal为每个线程维护一个单独的副本, 线程之间互不影响

     */

    private ThreadLocal<Integer> threadLocal = new ThreadLocal<Integer>() {

        @Override

        protected Integer initialValue() {

            return 0;

        }

    };

    //获取下一个序列值

    public int getNextNum() {

        threadLocal.set(threadLocal.get() + 1);

        return threadLocal.get();

    }

    /*

     */

    public static void main(String[] args) {

        ThreadLocalTest threadLocalTest = new ThreadLocalTest();

        Client client1 = new Client(threadLocalTest);

        Client client2 = new Client(threadLocalTest);

        Client client3 = new Client(threadLocalTest);

        Thread thread1 = new Thread(client1);

        Thread thread2 = new Thread(client2);

        Thread thread3 = new Thread(client3);

        thread1.start();

        thread2.start();

        thread3.start();

    }

    static class Client implements Runnable {

        private ThreadLocalTest threadLocalTest;

        public Client(ThreadLocalTest threadLocalTest) {

            this.threadLocalTest = threadLocalTest;

        }

        public void run() {

            for (int i = 0; i < 3; i++) {

                System.out.println("thread[" + Thread.currentThread().getName() + "] --> nextNumber=[" +

                        threadLocalTest.getNextNum() + "]");

            }

        }

    }

}