在《多執行緒採用鎖併發控制》一文中採用鎖保證了多執行緒下類的成員變數的同步。如果需要保證執行緒內部對變數的訪問是隔離的，執行緒內部對變數的操作不會影響其他的執行緒，這又該如何操作了。ThreadLocal物件通常用於防止對可變的單例項變數或全域性變數進行共享。

public class MyCounter implements Runnable {

	private static ThreadLocal<Long> count = new ThreadLocal<Long>(){
		public Long initialValue() {
			return 0L;
		}
	};
	
	public Long getNext() {
		count.set(count.get()+1);
		return count.get();
	}
	
	public synchronized void  run() {
		System.out.println("thread id:"+Thread.currentThread().getId()+",count:"+getNext());
		try {
			Thread.sleep(1000);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
	}

	public static void main(String[] args) {
		ExecutorService executorService = Executors.newFixedThreadPool(3);  
		MyCounter countThread = new MyCounter();
		for(int i=0; i<9; i++){
                   executorService.submit(countThread); 
                }  		
	}
}
 

thread id:10,count:1
thread id:12,count:1
thread id:11,count:1
thread id:12,count:2
thread id:10,count:2
thread id:12,count:3
thread id:11,count:2
thread id:12,count:4
thread id:10,count:3