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

代码示例：

public interface Data {

    String getRequest();

}

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 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 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);
        
    }
}

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具体一点，代码实现流程应该是这样的：

代码示例：

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;
    } 
    
}


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;
    }
}


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 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;
            }
        }
        
    }
}

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代码示例：

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 + "}";
    }
}

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();

    }
}

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