threadLocal测试用例，说明线程本地私有

Posted 2021-02-28 dashenaichicha

package thread.test;

public class ThreadLocalDemo {
	/**
	 * ThreadLocal变量，每个线程都有一个副本，互不干扰
	 */
	private static final ThreadLocal<String> THREAD_LOCAL = new ThreadLocal<>();

	public static void main(String[] args) throws Exception {
		new ThreadLocalDemo().threadLocalTest();
	}

	public void threadLocalTest() throws Exception {
		// 主线程设置值
		THREAD_LOCAL.set("1");
		String v = THREAD_LOCAL.get();
		System.out.println("Thread-0线程执行之前，" + Thread.currentThread().getName() + "线程取到的值：" + v);

		new Thread(new Runnable() {
			@Override
			public void run() {
				String v = THREAD_LOCAL.get();
				System.out.println(Thread.currentThread().getName() + "线程取到的值：" + v);
				// 设置 threadLocal(这也说明了每个线程都有一个threadLocal)
				THREAD_LOCAL.set("2");
				v = THREAD_LOCAL.get();
				System.out.println("重新设置之后，" + Thread.currentThread().getName() + "线程取到的值为：" + v);
				System.out.println(Thread.currentThread().getName() + "线程执行结束");
			}
		}).start();
		// 等待所有线程执行结束
		Thread.sleep(3000L);
		// main线程重新取,取到的是自己线程私有的本地线程私有变量
		v = THREAD_LOCAL.get();
		System.out.println("Thread-0线程执行之后，" + Thread.currentThread().getName() + "线程取到的值：" + v);
	}
}