AtomicLongMap的使用

AtomicLongMap是Google Guava项目的一个类，它是线程安全、支持并发访问的。

 

public class AtomicLongMapTest {
    private static int threadCount = 10; //线程数
    private static int loopNum = 5; //循环次数
    private static String key = "count";
    private static ExecutorService executorService = Executors.newFixedThreadPool(threadCount);
    
    //AtomicLongMap	线程安全，支持并发  
    private static AtomicLongMap<String> atomicLongMap = AtomicLongMap.create();
    
    //倒计时计数器
    private static CountDownLatch countDownLatch;

    public static void main(String[] args)throws Exception{  
    	test1();
    	test0();
    }
    
    private static void test0()throws Exception{
    	for(int i=1; i<=5; i++){
    		atomicLongMap.put("key"+i, i);
    	}
    	System.out.println(atomicLongMap);
    	
    	System.out.println(atomicLongMap.containsKey("key1")); //是否存在指定key
    	System.out.println(atomicLongMap.get("key1")); //获取指定key的值
    	
    	System.out.println(atomicLongMap.getAndAdd("key1", 1));
    	System.out.println(atomicLongMap.addAndGet("key1", 1));
    	
    	System.out.println(atomicLongMap.getAndIncrement("key1")); //值递增
    	System.out.println(atomicLongMap.incrementAndGet("key1"));
    	
    	System.out.println(atomicLongMap.getAndDecrement("key1")); //值递减
    	System.out.println(atomicLongMap.decrementAndGet("key1"));

    	System.out.println(atomicLongMap.removeIfZero("key1")); //删除值为0的key
    	atomicLongMap.remove("key1"); //删除指定的key
    	atomicLongMap.removeAllZeros(); //删除所有值为0的key
    	
    	System.out.println(atomicLongMap.size()); //key的数量
    	System.out.println(atomicLongMap.sum()); //求所有key值的和
    	
    	atomicLongMap.clear(); //清空
    	System.out.println(atomicLongMap.isEmpty()); //判断是否为空
    }
    
    private static void test1()throws Exception{
    	countDownLatch = new CountDownLatch(threadCount); //state值=threadCount 
    	
    	for(int i=1; i<=threadCount; i++){
    		executorService.execute(new Runnable() {
				@Override
				public void run() {
					for(int i=0; i<loopNum; i++){
						long value = atomicLongMap.incrementAndGet(key);
						System.out.println(Thread.currentThread().getName() + ": " + value);
					}
					
	                countDownLatch.countDown(); //state值减1  
				}
			});
    	}

        //等待直到state值为0，再继续往下执行  
        countDownLatch.await();  
        
		System.out.println(atomicLongMap.get(key));
    	executorService.shutdown();
    }
}