java多线程--信号量

package com.weigu.xiaochuang.project;

package com.weigu.xiaochuang.project;

import java.util.concurrent.Semaphore;
import java.util.concurrent.locks.ReentrantLock;

public class ResourceManage {
    private Semaphore semaphore;
    private boolean resourceArray[];
    private ReentrantLock lock;

    //初始化操作--以前没这样写过,进行赋值的关系
    public ResourceManage() {
        this.resourceArray = new boolean[10];   //存放厠所狀太
        this.semaphore = new Semaphore(10, true);//控制10个共享资源的使用，使用先进先出的公平模式进行共享;公平模式的信号量，先来的先获得信号量
        this.lock = new ReentrantLock(true);//公平模式的锁，先来的先选
        for (int i = 0; i < resourceArray.length; i++) {
            resourceArray[i] = true; //初始化为资源可用的情况
        }
    }

    public void useResource(int userId) {

        try{
            semaphore.acquire();
            int id = getResourceId();//占到一个坑
            System.out.print("userId:"+userId+"正在使用资源，资源id:"+id+"\n");
            Thread.sleep(100);//do something，相当于于使用资源
            resourceArray[id] = true;//退出这个坑
        }catch (InterruptedException e){
            e.printStackTrace();
        }finally {
            semaphore.release();//释放信号量，计数器加1
        }
    }

    public int getResourceId() {
        int id = -1;
        try {
            lock.lock();
            for (int i = 0; i < 10; i++) {
                if (resourceArray[i]) {
                    resourceArray[i] = false;
                    id = 1;
                    break;
                }
            }
        } finally {
            lock.unlock();
        }
        return id;
    }
}

 

public class ResourceUser implements Runnable {
    private ResourceManage resourceManage;
    private int userId;

    public ResourceUser(ResourceManage resourceManage, int userId) {
        this.resourceManage = resourceManage;
        this.userId = userId;
    }

    @Override
    public void run() {
        System.out.print("userId:" + userId + "准备使用资源...\n");
        resourceManage.useResource(userId);
        System.out.print("userId:" + userId + "使用资源完毕...\n");
    }

    public static void main(String[] args) {
        ResourceManage resourceManage = new ResourceManage();
        Thread[] threads = new Thread[100];  //创建100个线程,但是线程数组为空,
        for (int i = 0; i < 100; i++) {
            Thread thread = new Thread(new ResourceUser(resourceManage, i));//创建线程2,将任务加入到线程
            threads[i] = thread; //将线程赋值给线程数组
        }
        for (int i = 0; i < 100; i++) {
            Thread thread = threads[i];  //获取单个线程,进行启动线程
            try {
                thread.start();//启动线程
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
Semaphore的使用：

Semaphore使用时需要先构建一个参数来指定共享资源的数量，Semaphore构造完成后即是获取Semaphore、共享资源使用完毕后释放Semaphore。

Semaphore semaphore = new Semaphore(10,true);
semaphore.acquire();