Java并发学习之十五——使用读写锁同步数据访问

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读写锁重要的是写锁的使用，只用一个入口。

下面是读写锁使用的例子

package chapter2;

import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class PricesInfo {
	private int price1;
	private int price2;
	private ReadWriteLock lock;
	public PricesInfo(){
		price1 = 1;
		price2 = 1;
		lock = new ReentrantReadWriteLock();

	}
	public int getPrice1() {
		lock.readLock().lock();
		int value = price1;
		lock.readLock().unlock();
		return value;
	}
	public void setPrice1(int price1) {
		this.price1 = price1;
	}
	public int getPrice2() {
		lock.readLock().lock();
		int value = price2;
		lock.readLock().unlock();
		return value;
	}
	public void setPrice2(int price2) {
		this.price2 = price2;
	}

	public void setPrices(int price1,int price2){
		lock.writeLock().lock();
		this.price1 = price1;
		this.price2 = price2;
		lock.writeLock().unlock();
	}
}

package chapter2;

public class Reader implements Runnable{

	private PricesInfo pricesInfo;
	public Reader(PricesInfo pricesInfo){
		this.pricesInfo = pricesInfo;
	}
	@Override
	public void run() {

		for(int i=0;i<10;i++){

			System.out.printf("%s:Price 2:%d\n", Thread.currentThread().getName(),pricesInfo.getPrice2());
			System.out.printf("%s:Price 1:%d\n", Thread.currentThread().getName(),pricesInfo.getPrice1());
		}

	}
}

package chapter2;

import java.util.Random;

public class Writer implements Runnable{
	private PricesInfo pricesInfo;
	public Writer(PricesInfo pricesInfo){
		this.pricesInfo = pricesInfo;
	}
	@Override
	public void run() {

		for(int i=0;i<3;i++){
			int p1 = new Random().nextInt(47);
			int p2 = new Random().nextInt(47)*10;

			System.out.println("Writer:Attempt to modify the prices."+p1+"    price2:"+p2);
			pricesInfo.setPrices(p1, p2);
			System.out.println("Writer:Prices have been modified."+p1+"    price2:"+p2);
			try {
				Thread.sleep(2);
			} catch (Exception e) {
				// TODO: handle exception
			}
		}
	}
}

package chapter2;

public class Main6 {

	/**
	 * <p>
	 * </p>
	 * @author zhangjunshuai
	 * @date 2014-9-17 上午11:17:50
	 * @param args
	 */
	public static void main(String[] args) {

		PricesInfo pricesInfo = new PricesInfo();
		Reader reader[] = new Reader[5];
		Thread threadsReader[] = new Thread[5];
		for (int i = 0; i < threadsReader.length; i++) {
			reader[i] = new Reader(pricesInfo);
			threadsReader[i]=new Thread(reader[i]);
		}
		Writer writer = new Writer(pricesInfo);
		Thread threadWriter = new Thread(writer);
		for (int i = 0; i < threadsReader.length; i++) {
			threadsReader[i].start();
		}
		threadWriter.start();
	}

}