Java用讀-寫鎖來封裝Map

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內容：利用ReentrantReadWriteLock來封裝Map，從而使它能在多個讀線程之間被安全分享，並且仍然能避免“讀-寫”或“寫-寫”衝突。記住重要的一點是：讀-寫鎖實現的加鎖策略中，允許多個讀操作同時進行，但每次只允許一個寫操作。

public class ReadWriteMap<K, V> {private final Map<K, V> map;private final ReadWriteLock lock = new ReentrantReadWriteLock();private final Lock r = lock.readLock();private final Lock w = lock.writeLock();public ReadWriteMap(Map<K, V> map) {this.map = map;}public V put(K key, V value) {w.lock();System.out.println("擷取寫鎖");try {return map.put(key, value);} finally {w.unlock();System.out.println("釋放寫鎖");}}public V get(K key) {r.lock();System.out.println("擷取讀鎖");try {return map.get(key);} finally  {r.unlock();System.out.println("釋放讀鎖");}}public static void main(String[] args) throws InterruptedException {final Map<Integer, String> map = new HashMap<Integer, String>();final ReadWriteMap<Integer, String> readWriteMap = new ReadWriteMap<Integer, String>(map);ExecutorService executorService = Executors.newCachedThreadPool();for (int i = 0; i <= 10; i++) {final int tmp = i;executorService.execute(new Runnable() {@Overridepublic void run() {readWriteMap.put(tmp, tmp+"");}});if ((i & 1) == 1) {executorService.execute(new Runnable() {@Overridepublic void run() {System.out.println(readWriteMap.get(new Random().nextInt(6)));}});}}executorService.shutdown();}}

Java用讀-寫鎖來封裝Map