java 多线程（threadlocal）

package com.fredric.demo;

import java.util.Random;

public class App {

    public static class MyRunnable1 implements Runnable {
        //ThreadLocal是一个线程局部变量
        private ThreadLocal<String> threadlocal
                = new ThreadLocal<String>();

        private int tmp;

        public void run() {
            //threadlocal 包含方法：
            //set:创建一个线程本地变量
            //remove:移除该本地变量
            //get:获取该本地变量的值
            //在hibernate中被用于本地session管理
            threadlocal.set("Name:"+new Random().nextInt(10));
            int i  = new Random().nextInt(10);

            System.out.println("set tmp: " + i);

            tmp = i;
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName() + " : " + threadlocal.get() + "  " + tmp);
        }
    }

    public static void main(String[] args) {
        MyRunnable1 r = new MyRunnable1();
        Thread t1 = new Thread(r,"thread1");
        Thread t2 = new Thread(r,"thread2");
        t1.start();
        t2.start();

        /*
        输出如下：局部变量没有改变，而Threadlocal每个线程有自己独立的副本
        set tmp: 0
        set tmp: 1
        thread1 : Name:3  1
        thread2 : Name:4  1 */
    }
}