Java并发学习之十五——使用读写锁同步数据访问

清疚 2022-08-12 02:59 134阅读 0赞

本文是学习网络上的文章时的总结，感谢大家无私的分享。

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();
    	}
    
    }