java并发编程使用Semaphore创建字符串池

类Semaphore可以有效地对并发执行并发执行任务的线程数量进行限制，这种功能可以应用在pool池技术中，可以设置同时访问pool池中数据的线程数量。

本实验的功能是同时有若干个线程可以访问池中的数据，但同时只有一个线程可以取得数据，使用完毕后再放回池中。

package cn.yu.test;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Semaphore;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

public class ListPool {
  private int poolMaxSize = 3;
  private int semaphorePermits = 5;
  private List<String> list = new ArrayList<String>();
  private Semaphore concurrencySemaphore = new Semaphore(semaphorePermits);
  private ReentrantLock lock = new ReentrantLock();
  private Condition condition = lock.newCondition();
  public ListPool() {
	  super();
	  for(int i = 0;i<poolMaxSize;i++) {
		  list.add("Semaphore"+(i+1));
	  }  
  }
  public String get() {
	  String getString = null;
	  try {
		concurrencySemaphore.acquire();
		lock.lock();
		  while(list.size() == 0) {
			  condition.await();
		  }
		  getString = list.remove(0);
		  lock.unlock();
	} catch (InterruptedException e) {
		
		e.printStackTrace();
	}
	  
	  return getString;
  }
   public void put(String stringValue) {
	   lock.lock();
	   list.add(stringValue);
	   condition.signalAll();
	   lock.unlock();
	   concurrencySemaphore.release();
   }
}

package cn.yu.test;

public class MyThread extends Thread{
 private ListPool listPool;
 public MyThread(ListPool listPool) {
	 super();
	 this.listPool = listPool;
 }
  public void run() {
	  for(int i = 0;i<Integer.MAX_VALUE;i++) {
		  String getString = listPool.get();
		  System.out.println(Thread.currentThread().getName()+"取得值"+getString);
		  listPool.put(getString);
	  }
  }
}

package cn.yu.test;

import java.util.Scanner;

public class Test {
	 
    public static void main(String [] args) {
		
    
    	ListPool pool = new ListPool();
    	MyThread[] threadArray = new MyThread[12];
    	for(int i =0;i<threadArray.length;i++) {
    		threadArray[i] = new MyThread(pool);
    	}
     	for(int i =0;i<threadArray.length;i++) {
     		threadArray[i] = new MyThread(pool);
     	}
     	for(int i = 0;i<threadArray.length;i++) {
     		threadArray[i].start();
     	}
    	
     }

}

运行结果：

Thread-2取得值Semaphore1
Thread-7取得值Semaphore1
Thread-5取得值Semaphore3
Thread-6取得值Semaphore3
Thread-6取得值Semaphore3
Thread-6取得值Semaphore3
Thread-6取得值Semaphore3
Thread-6取得值Semaphore3
Thread-6取得值Semaphore3
Thread-6取得值Semaphore3
Thread-6取得值Semaphore3
Thread-6取得值Semaphore3
Thread-2取得值Semaphore3
Thread-7取得值Semaphore1
Thread-11取得值Semaphore2
...............

java并发编程使用Semaphore创建字符串池

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