多线程同步写入，单线程读出

最新推荐文章于 2021-03-04 10:27:01 发布

原创最新推荐文章于 2021-03-04 10:27:01 发布 · 277 阅读

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#Lock Future

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本文通过一个模拟项目，展示了如何使用多线程处理大文件，并利用锁机制保证数据的一致性和完整性。采用ReentrantLock进行并发控制，确保多个线程在写入数据时不会发生冲突。

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把项目中一个大文件对比进行了简单了模拟，多线程将大文件下的多个文件分割，lock控制差异同步写入到一个list中；当所有线程执行完毕，read 所有内容。


package cn.com.ld.study.thread;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * @filename: LockTest
 * @description: TODO
 * @author java 小生
 * @date 2013-2-18 下午6:07:34
 */
public class LockTest {
	Lock rlock = new ReentrantReadWriteLock().writeLock();
	Lock lock = new ReentrantLock();// 锁
	private Collection<String> strc = new ArrayList<String>();
	private int readSequence;
	private int writeTimes = 0;

	LockTest(int writeTimes) {
		this.writeTimes = writeTimes;
	}

	public boolean write(String name) {
		try {
			lock.lock();
			readSequence++;
			System.out.println(name + " 被" + readSequence + "次写入");
			strc.add(name + readSequence);
		} finally {
			lock.unlock();
		}
		return writeTimes == readSequence ? true : false;

	}

	public void read() {
		System.out.println("读取写入内容开始.....");
		for (Iterator<String> iterator = strc.iterator(); iterator.hasNext();) {
			String type = (String) iterator.next();
			System.out.println(type+" 被输出。。。。");

		}
		System.out.println("读取写入内容结束.....");
	}

	public static void main(String[] args) throws InterruptedException {
		final LockTest lockTest = new LockTest(100);
		List<Future<Boolean>> fList = new ArrayList<Future<Boolean>>();
		Callable<Boolean> write = new Callable<Boolean>() {

			@Override
			public Boolean call() throws Exception {
				return lockTest.write("张三");
			}

		};

		ExecutorService cachedService = Executors.newCachedThreadPool();
		Future<Boolean> future = null;
		for (int i = 0; i < 100; i++) {
			future = cachedService.submit(write);
			fList.add(future);
		}

		while (true) {
			int writeLent = lockTest.strc.size() ;
			if (writeLent == 100 && fList.get(99).isDone()) {
				lockTest.read() ;
				break ;
			}
		}

	}
}