ThreadLocal的使用

       ThreadLocal即线程变量。是一个以ThreadLocal对象为键、任意对象为值得存储结构

package com;import java.util.concurrent.TimeUnit;public class Profiler {		//第一次get()方法调用时候进行初始化（如果set方法没有调用），每个线程会调用一次	private static final ThreadLocal
    
      TIME_THREADLOCAL = new ThreadLocal
     
      (){		@Override		protected Long initialValue() {			return System.currentTimeMillis();		}			};		public static final void begin(){		TIME_THREADLOCAL.set(System.currentTimeMillis());	}		public static final long end(){		return System.currentTimeMillis() - TIME_THREADLOCAL.get();	}		public static void main(String[] args) throws InterruptedException{		Profiler.begin();		TimeUnit.SECONDS.sleep(1);		System.out.println("COST : "+ Profiler.end() + " mills");	}}