Java线程设计模式（五）

多线程的设计模式：Future模式、Master-Worker模式，生产消费者模式

public interface Data {

    String getRequest();
}

　　

public class FutureClient  {
    public Data request(final String queryStr){
        //1 我想要一个代理对象（Data接口的实现类）先返回给发送请求的客户端，告诉他请求已经接收到，可以做其他的事情
        final FutureData futureData = new FutureData();
        //2 启动一个新的线程，去加载真实的数据，传递给这个代理对象
        new Thread(new Runnable() {
            @Override
            public void run() {
                //3 这个新的线程可以去慢慢的加载真实对象，然后传递给代理对象
                RealData realData = new RealData(queryStr);
                futureData.setRealData(realData);
            }
        }).start();

        return futureData;
    }
}

　　

public class FutureData implements Data{

    private RealData realData ;

    private boolean isReady = false;

    public synchronized void setRealData(RealData realData) {
        //如果已经装载完毕了，就直接返回
        if(isReady){
            return;
        }
        //如果没装载，进行装载真实对象
        this.realData = realData;
        isReady = true;
        //进行通知
        notify();
    }

    @Override
    public synchronized String getRequest() {
        //如果没装载好 程序就一直处于阻塞状态
        while(!isReady){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        //装载好直接获取数据即可
        return this.realData.getRequest();
    }
}

　　

public class RealData implements Data{

    private String result ;

    public RealData (String queryStr){
        System.out.println("根据" + queryStr + "进行查询，这是一个很耗时的操作..");
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("操作完毕，获取结果");
        result = "查询结果";
    }

    @Override
    public String getRequest() {
        return result;
    }
}

　　

public class Main {
    public static void main(String[] args) throws InterruptedException {

        FutureClient fc = new FutureClient();
        Data data = fc.request("请求参数");
        System.out.println("请求发送成功!");
        System.out.println("做其他的事情...");

        String result = data.getRequest();
        System.out.println(result);
    }
}

　　

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;

public class Master {
    //1 有一个盛放任务的容器
    private ConcurrentLinkedQueue<Task> workQueue=new ConcurrentLinkedQueue<Task>();

    //2 需要有一个盛放worker的集合
    private HashMap<String,Thread> workers =new HashMap<String, Thread>();

    //3 需要有一个盛放每一个worker执行任务的结果集合
    private ConcurrentHashMap<String,Object> resultMap=new ConcurrentHashMap<String, Object>();

    //4 构造方法
    public Master(Worker worker,int workerCount){
        worker.setWorkQueue(this.workQueue);
        worker.setResultMap(this.resultMap);
        for(int i = 0; i < workerCount; i ++){
            this.workers.put(Integer.toString(i), new Thread(worker));
        }
    }
    //5 需要一个提交任务的方法
    public void submit(Task task) {
        this.workQueue.add(task);
    }
    //6 需要有一个执行的方法，启动所有的worker方法去执行任务
    public void execute(){
        for(Map.Entry<String,Thread> me: workers.entrySet()){
            me.getValue().start();
        }
    }
    //7 判断是否运行结束的方法
    public boolean isComplete() {
        for(Map.Entry<String, Thread> me : workers.entrySet()){
            if(me.getValue().getState() != Thread.State.TERMINATED){
                return false;
            }
        }
        return true;
    }

    //8 计算结果方法
    public int getResult() {
        int priceResult = 0;
        for(Map.Entry<String, Object> me : resultMap.entrySet()){
            priceResult += (Integer)me.getValue();
        }
        return priceResult;
    }
}

　　

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;

public class Worker implements  Runnable{
    private ConcurrentLinkedQueue<Task> workQueue;
    private ConcurrentHashMap<String,Object> resultMap;
    public void setWorkQueue(ConcurrentLinkedQueue<Task> workQueue) {
        this.workQueue=workQueue;
    }
    public void setResultMap(ConcurrentHashMap<String,Object> resultMap){
        this.resultMap=resultMap;
    }
    @Override
    public void run(){
        while (true){
            Task input=this.workQueue.poll();
            if(input==null) break;
            Object output=handle(input);
            this.resultMap.put(Integer.toString(input.getId()),output);
        }
    }
    private Object handle(Task input){
        Object output=null;
        try {
            //处理任务的耗时。。 比如说进行操作数据库。。。
            Thread.sleep(500);
            output = input.getPrice();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return output;
    }
}

　　

public class Task {
    private int id;
    private int price ;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public int getPrice() {
        return price;
    }
    public void setPrice(int price) {
        this.price = price;
    }
}

　　

import java.util.Random;

public class Main {
    public static void main(String[] args) {
        Master master = new Master(new Worker(), 20);

        Random r = new Random();
        for (int i = 1; i <= 100; i++) {
            Task t = new Task();
            t.setId(i);
            t.setPrice(r.nextInt(1000));
            master.submit(t);
        }
        master.execute();
        long start = System.currentTimeMillis();

        while (true) {
            if (master.isComplete()) {
                long end = System.currentTimeMillis() - start;
                int priceResult = master.getResult();
                System.out.println("最终结果：" + priceResult + ", 执行时间：" + end);
                break;
            }
        }

    }
}

　　

生产者-消费者

public final class Data {
    private String id;
    private String name;

    public Data(String id, String name){
        this.id = id;
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString(){
        return "{id: " + id + ", name: " + name + "}";
    }
}

　　

import java.util.Random;
import java.util.concurrent.BlockingQueue;

public class Consumer implements  Runnable{
    private BlockingQueue<Data> queue;
    public Consumer(BlockingQueue queue){
        this.queue=queue;
    }
    //随机对象
    private static Random r = new Random();
    @Override
    public void run() {
        while(true){
            try {
                //获取数据
                Data data = this.queue.take();
                //进行数据处理。休眠0 - 1000毫秒模拟耗时
                Thread.sleep(r.nextInt(1000));
                System.out.println("当前消费线程：" + Thread.currentThread().getName() + "， 消费成功，消费数据为id: " + data.getId());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

　　

public class Provider implements Runnable{

    //共享缓存区
    private BlockingQueue<Data> queue;
    //多线程间是否启动变量，有强制从主内存中刷新的功能。即时返回线程的状态
    private volatile boolean isRunning = true;
    //id生成器
    private static AtomicInteger count = new AtomicInteger();
    //随机对象
    private static Random r = new Random();

    public Provider(BlockingQueue queue){
        this.queue = queue;
    }

    @Override
    public void run() {
        while(isRunning){
            try {
                //随机休眠0 - 1000 毫秒 表示获取数据(产生数据的耗时)
                Thread.sleep(r.nextInt(1000));
                //获取的数据进行累计...
                int id = count.incrementAndGet();
                //比如通过一个getData方法获取了
                Data data = new Data(Integer.toString(id), "数据" + id);
                System.out.println("当前线程:" + Thread.currentThread().getName() + ", 获取了数据，id为:" + id + ", 进行装载到公共缓冲区中...");
                if(!this.queue.offer(data, 2, TimeUnit.SECONDS)){
                    System.out.println("提交缓冲区数据失败....");
                    //do something... 比如重新提交
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public void stop(){
        this.isRunning = false;
    }
}

　　

public class Main {

    public static void main(String[] args) throws Exception {
        //内存缓冲区
        BlockingQueue<Data> queue = new LinkedBlockingQueue<Data>(10);
        //生产者
        Provider p1 = new Provider(queue);

        Provider p2 = new Provider(queue);
        Provider p3 = new Provider(queue);
        //消费者
        Consumer c1 = new Consumer(queue);
        Consumer c2 = new Consumer(queue);
        Consumer c3 = new Consumer(queue);
        //创建线程池运行,这是一个缓存的线程池，可以创建无穷大的线程，没有任务的时候不创建线程。空闲线程存活时间为60s（默认值）

        ExecutorService cachePool = Executors.newCachedThreadPool();
        cachePool.execute(p1);
        cachePool.execute(p2);
        cachePool.execute(p3);
        cachePool.execute(c1);
        cachePool.execute(c2);
        cachePool.execute(c3);

        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        p1.stop();
        p2.stop();
        p3.stop();
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
//		cachePool.shutdown();
//		cachePool.shutdownNow();

    }
}