ThreadLocal基本原理及运用

ThreadLocal提供本地线程变量。这个变量里面的值（通过get方法获取）是和其他线程分割开来的，变量的值只有当前线程能访问到，不像一般的类型比如Person,Student类型的变量，只要访问到声明该变量的对象，即可访问其全部内容，而且各个线程的访问的数据是无差别的。

static ThreadLocal<String> stringThreadLocal = new ThreadLocal<>();

@Test
public  void test01(){
    Thread thread1 = new Thread(){
        @Override
        public void run() {
         stringThreadLocal.set("threadName===>"+Thread.currentThread().getName());
            System.out.println(this.getName()+" thread get the value:"+stringThreadLocal.get());

        }
    };
    Thread thread2 = new Thread(){
        @Override
        public void run() {
         stringThreadLocal.set("threadName===>"+Thread.currentThread().getName());
            System.out.println(this.getName()+" thread get the value:"+stringThreadLocal.get());

        }
    };
    Thread thread3 = new Thread(){
        @Override
        public void run() {
         stringThreadLocal.set("threadName===>"+Thread.currentThread().getName());
            System.out.println(this.getName()+" thread get the value:"+stringThreadLocal.get());
        }
    };

    thread1.start();
    thread2.start();
    thread3.start();
    System.out.println("main线程调用set方法之前："+stringThreadLocal.get());
    stringThreadLocal.set("main 线程set的值");
    System.out.println("main线程调用set方法之后："+stringThreadLocal.get());
}

功能就是往线程里传值。