ThreadLocal类的用法

ThreadLocal类的用法

在ThreadLocal类中有一个Map，用于存储每一个线程的变量的副本，同步机制采用了“以时间换空间”的方式，而ThreadLocal采用了“以空间换时间”的方式

案例：

package demo;

import java.util.Random;

public class ThreadLocalShareData2 {
    static ThreadLocal<People> threadLocal = new ThreadLocal<People>();
    public static void main(String[] args) {
        for (int i = 0; i < 2; i++) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    int data = new Random().nextInt();
                    People people = new People().getInstance();
                    people.setName("name"+data);
                    people.setAge(data);
//                    System.out.println(Thread.currentThread().getName()+" set name "+people.getName()+" set age "+people.getAge());
                    new A().get();
                    new B().get();
                }
            }).start();
        }
    }

    static class A{
        public void get(){
            System.out.println("A: "+Thread.currentThread().getName() +"get name "+new People().getInstance().getName()+" get age "+new People().getInstance().getAge());
        }
    }
    static class B{
        public void get(){
            System.out.println("B: "+Thread.currentThread().getName() +"get name "+new People().getInstance().getName()+" get age "+new People().getInstance().getAge());
        }
    }
    static class People{
        private People(){

        }
        public People getInstance(){
            People people = threadLocal.get();
            if(people == null){
                people = new People();
                threadLocal.set(people);
            }
            return people;
        }
        private int age;
        private String name;
        public int getAge() {
            return age;
        }
        public String getName() {
            return name;
        }
        public void setAge(int age) {
            this.age = age;
        }
        public void setName(String name) {
            this.name = name;
        }
    }
}

执行结果：