JDK 5.0 Concurrency Utilities 并发处理（4）Semaphore 信号量

Semaphore 信号量

  1package com.vinko.test.concurrent;
  2
  3import java.util.Calendar;
  4import java.util.concurrent.Semaphore;
  5import java.util.concurrent.locks.Condition;
  6import java.util.concurrent.locks.Lock;
  7import java.util.concurrent.locks.ReentrantLock;
  8
  9public class TestSemaphore {
 10
 11    private ReentrantLock lock = null;
 12    private Condition condition = null;
 13    private Semaphore semaphore = null;
 14    
 15    public TestSemaphore() {
 16        lock = new ReentrantLock();
 17        condition = lock.newCondition();
 18        semaphore = new Semaphore(2, true);
 19    }
 20    
 21    /** *//**
 22     * @param args
 23     */
 24    public static void main(String[] args) {
 25
 26        TestSemaphore tester = new TestSemaphore();
 27        
 28        tester.test();
 29    }
 30    
 31    public Lock getLock() {
 32        return lock;
 33    }
 34    
 35    public Condition getCondition() {
 36        return condition;
 37    }
 38    
 39    public Semaphore getSemaphore() {
 40        return semaphore;
 41    }
 42    
 43    public void test() {
 44        try {
 45            /**//*
 46            semaphore.acquire();
 47            System.out.println("get semaphore");
 48            
 49            semaphore.acquire();
 50            System.out.println("get semaphore");
 51
 52            semaphore.release();
 53
 54            semaphore.acquire();
 55            System.out.println("get semaphore");
 56            
 57            semaphore.acquire();
 58            System.out.println("get semaphore");
 59            */
 60            
 61            new Thread(new TestThread(this)).start();
 62            new Thread(new TestThread(this)).start();
 63            new Thread(new TestThread(this)).start();
 64            new Thread(new TestThread(this)).start();
 65            
 66            Thread.sleep(3000);
 67            
 68            lock.lock();
 69            condition.signal();
 70//            condition.signal();
 71//            condition.signalAll();
 72            lock.unlock();
 73            
 74        } catch (InterruptedException e) {
 75            e.printStackTrace();
 76        }
 77    }
 78
 79}
 80
 81class TestThread implements Runnable {
 82    
 83    private TestSemaphore tester = null;
 84    
 85    public TestThread(TestSemaphore tester) {
 86        this.tester = tester;
 87    }
 88    
 89    public void run() {
 90        
 91        Calendar now = Calendar.getInstance();
 92        
 93        System.out.println(now.getTime() + " " + Thread.currentThread() + " started.");
 94
 95        while (true) {
 96            try {
 97                tester.getLock().lock();
 98                tester.getCondition().await();
 99                tester.getLock().unlock();
100                
101                Calendar now1 = Calendar.getInstance();
102                System.out.println(now1.getTime() + " " + Thread.currentThread() + " got signal.");
103                
104                tester.getSemaphore().acquire();
105                
106                Calendar now2 = Calendar.getInstance();
107                System.out.println(now2.getTime() + " " + Thread.currentThread() + " got semaphore.");
108                
109//                tester.getSemaphore().release();
110                
111            } catch (InterruptedException e) {
112                e.printStackTrace();
113            }
114        }
115    }
116}