秒杀多线程第十四篇 读者写者问题继 读写锁SRWLock （续）

java 包实现了读写锁的操作：

package com.multithread.readwritelock;



import java.util.concurrent.CountDownLatch;

import java.util.concurrent.Executor;

import java.util.concurrent.Executors;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReadWriteLock;

import java.util.concurrent.locks.ReentrantReadWriteLock;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;



import com.multithread.main.ExampleInterface;

import com.multithread.readwrite.WriteThread;



public class ReadWriteLockExample extends ExampleInterface {



    public ReadWriteLock mReadwriteLock = new ReentrantReadWriteLock(false);

    public File mFile = null;

    public int mCash = 10000;

    public CountDownLatch mLatchDown = new CountDownLatch(6);

    private boolean mStopedFlag = false;



    @Override

    public void startDemo() {

        // TODO Auto-generated method stub

        mFile = new File("H:\\Project\\SST\\123.txt");

        try {



            mFile.createNewFile();

            Executor mEcecutor = Executors.newFixedThreadPool(2 + 4);

            mEcecutor.execute(new Reader("Reader1"));

            mEcecutor.execute(new Reader("Reader2"));

            mEcecutor.execute(new Reader("Reader3"));

            mEcecutor.execute(new Reader("Reader4"));

            mEcecutor.execute(new Writer("Writer1", 2000));

            mEcecutor.execute(new Writer("Writer2", -3000));



            mLatchDown.await();

            System.out.println("[startDemo]" + "Demo down");



        } catch (IOException | InterruptedException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }



    public class Reader extends Thread {



        public String name = null;

        boolean flag = true;

        private int index = 0;



        public Reader(String name) {

            this.name = name;

        }



        @Override

        public void run() {

            while (flag) {

                try {

                    mReadwriteLock.readLock().lock();

                    System.out.println("[Reader]" + name + "start");

                    Thread.sleep((long) (Math.random() * 100));

                    if (!mStopedFlag) {

                        System.out.println("[Reader]" + name + "get mcash now:"

                                + mCash);

                    } else {

                        flag = false;

                    }

                    Thread.sleep((long) (Math.random() * 100));

                    System.out.println("[Reader]" + name + "down");

                    mReadwriteLock.readLock().unlock();

                    Thread.sleep((long) (Math.random() * 1000));

                } catch (InterruptedException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                }





            }

            mLatchDown.countDown();



        }



    }



    public class Writer extends Thread {



        public String name = null;

        boolean flag = true;

        private int index = 0;

        private int cash = 0;



        public Writer(String name, int addcash) {

            this.name = name;

            this.cash = addcash;

        }



        @Override

        public void run() {

            System.out.println("[Writer]" + name + "start");

            while (flag) {



                try {

                    mReadwriteLock.writeLock().lock();

                    System.out.println("[Writer]" + name + "start");

                    Thread.sleep((long) (Math.random() * 100));

                    int oldcash = mCash;

                    if (mCash <= 0) {

                        flag = false;

                        mStopedFlag = true;

                    } else {

                        mCash += cash;

                        System.out.println("[Writer]" + name

                                + "operator cash old:" + oldcash + " To:"

                                + mCash);

                    }

                    Thread.sleep((long) (Math.random() * 100));

                    System.out.println("[Writer]" + name + "down");

                    mReadwriteLock.writeLock().unlock();

                    Thread.sleep((long) (Math.random() * 1000));

                } catch (InterruptedException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                }



            }

            mLatchDown.countDown();

        }



    }



}

读写锁的特点就是：

1.写者与读者是互斥的

2.每个写者之间是互斥的

3.读者之间可以同时进行