在多線程開發中，經常會出現一種情況，我們希望讀寫分離。就是對于讀取這個動作來說，可以同時有多個線程同時去讀取這個資源，但是對于寫這個動作來說，只能同時有一個線程來操作，而且同時，當有一個寫線程在操作這個資源的時候，其他的讀線程是不能來操作這個資源的，這樣就極大的發揮了多線程的特點，能很好的將多線程的能力發揮出來。
在Java中，ReadWriteLock這個接口就為我們實現了這個需求，通過他的實現類ReentrantReadWriteLock我們可以很簡單的來實現剛才的效果，下面我們使用一個例子來說明這個類的用法。
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package com.bird.concursey.charpet3; import java.util.concurrent.locks.ReadWriteLock; import java.util.concurrent.locks.ReentrantReadWriteLock; public class PricesInfo { private double price1; private double price2; private ReadWriteLock lock; public PricesInfo() { price1 = 1.0; price2 = 2.0; lock = new ReentrantReadWriteLock(); } public double getPrice1() { //讀取資源鎖定 lock.readLock().lock(); double value = price1; lock.readLock().unlock(); return value; } public double getPrice2() { lock.readLock().lock(); double value = price2; lock.readLock().unlock(); return value; } public void setPrices(double price1, double price2) { lock.writeLock().lock(); this.price1 = price1; this.price2 = price2; lock.writeLock().unlock(); } } |
下面是讀和寫兩個不同的類
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package com.bird.concursey.charpet3; 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 1: %f\n", Thread.currentThread() .getName(), pricesInfo.getPrice1()); System.out.printf("%s: Price 2: %f\n", Thread.currentThread() .getName(), pricesInfo.getPrice2()); } } } |
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package com.bird.concursey.charpet3; 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++) { System.out.printf("Writer: Attempt to modify the prices.\n"); pricesInfo.setPrices(Math.random() * 10, Math.random( ) * 8); System.out.printf("Writer: Prices have been modified.\n"); try { Thread.sleep(2); } catch (InterruptedException e) { e.printStackTrace(); } } } public static void main(String[] args) { PricesInfo pricesInfo = new PricesInfo(); Reader readers[] = new Reader[5]; Thread threadsReader[] = new Thread[5]; for (int i = 0; i < 5; i++){ readers[i] = new Reader(pricesInfo); threadsReader[i] = new Thread(readers[i]); } Writer writer = new Writer(pricesInfo); Thread threadWriter = new Thread(writer); for (int i = 0; i < 5; i++){ threadsReader[i].start(); } threadWriter.start(); } } |
總結
以上就是本文關于Java多線程之readwritelock讀寫分離的實現代碼的全部內容，希望對大家有所幫助。有什么問題可以隨時留言，小編會及時回復大家的。感謝朋友們對服務器之家網站的支持。
原文鏈接：http://blog.csdn.net/a352193394/article/details/39405287#comments
