14.ThreadLocal

ThreadLocal

    1.线程局部变量，是一种多线程并发访问变量的解决方案，与同步技术 synchronize 加锁的方式不同，threadlocal完全不提供锁，而使用

       空间换时间的手段，为每个线程提供变量的独立副本，一保证现成的安全。

    2.在并发不是很高的时候，加锁的性能会更好，但是作为一套完全无关的线程安全解决方案，减少锁的竞争。

package demo3;
import java.util.concurrent.TimeUnit;
/**
 * Created by liudan on 2017/7/7.
 */
public class MyThread1 {
   
     
    public static ThreadLocal<String> threadLocalString = new ThreadLocal<String>();
    public void setThreadLocalString(String string) {
        threadLocalString.set(string);
    }
    public void getThreadLocalString() {
        System.err.println("◆：" + Thread.currentThread().getName() + "：" + threadLocalString.get());
    }
    public static void main(String[] args) {
        final MyThread1 myThread1 = new MyThread1();
        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                myThread1.setThreadLocalString("张帅");
                myThread1.getThreadLocalString();
            }
        },"T0000-01");
        Thread t2 = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    TimeUnit.SECONDS.sleep(0);
                    myThread1.setThreadLocalString("张帅1111");
                    myThread1.getThreadLocalString();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"T0000-02");
        t1.start();
        t2.start();
    }
}
输出：
◆：T0000-01：张帅
◆：T0000-02：张帅1111

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