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import java.util.concurrent.Callable;import java.util.concurrent.ExecutionException;import java.util.concurrent.Future;import java.util.concurrent.FutureTask;import java.util.concurrent.LinkedBlockingQueue;/*通过一个简单的例子研究一个典型的ActiveObject的实现*/public class ActiveObject {	/*为了方便，将所有相关的类都定义在一个class内*/	public void startTest() {		ServiceProxy proxy = new ServiceProxy();		Client client = new Client(proxy);				client.getNumberOfCustomers();		client.getBalance();	}		/*模拟客户端，此客户端调用proxy的异步方法，并保存Future对象，在晚些时候通过Future获取调用结果.	 * */	public class Client {		private ServiceProxy proxy = null;		private Future
   
     getNumberOfCustomers = null;		private Future
    
      getBalance = null;				public Client(ServiceProxy proxy) {			super();			this.proxy = proxy;		}				public void getNumberOfCustomers() {			getNumberOfCustomers = proxy.getNumberOfCustomers();			try {				System.out.println("Number of customers = "+getNumberOfCustomers.get());			} catch (InterruptedException | ExecutionException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}				public void getBalance() {			getBalance = proxy.getBalance();			try {				System.out.println("Balance = "+getBalance.get());			} catch (InterruptedException | ExecutionException e) {				// TODO Auto-generated catch block				e.printStackTrace();			}		}	}		/*对client提供业务调用接口，返回Future给client，内部使用Scheduler维护methodRequest*/	public class ServiceProxy {		private Scheduler scheduler = new Scheduler();		private Servant servant = new Servant(); 		/*将这个servant封装到MethodRequest中，实际使用Servant必然需要一个继承体系，不同的业务使用不同的Servant*/				public Future
     
       getNumberOfCustomers() {			/*生成一个MethodRequest对象，并通过scheduler加入队列。*/			MethodRequestGetCustomerNumber request = new MethodRequestGetCustomerNumber(servant);			return (Future
      
       )scheduler.enqueue(request);		}								public Future
       
         getBalance() {			MethodRequestGetBalance request = new MethodRequestGetBalance(servant);			return (Future
        
         )scheduler.enqueue(request); } } /*封装客户端的调用*/ public abstract class MethodRequestInteger implements Callable
         
          { protected int requestType = 0; } public abstract class MethodRequestDouble implements Callable
          
           { protected int requestType = 0; } public class MethodRequestGetCustomerNumber extends MethodRequestInteger { private Servant servant = null; public MethodRequestGetCustomerNumber(Servant servant) { super(); this.servant = servant; } @Override public Integer call() throws Exception { // TODO Auto-generated method stub return servant.getNumberOfCustomers(); } } public class MethodRequestGetBalance extends MethodRequestDouble { private Servant servant = null; public MethodRequestGetBalance(Servant servant) { super(); this.servant = servant; } @Override public Double call() throws Exception { // TODO Auto-generated method stub return servant.getBalance(); } } /*维护请求队列，并调用队列中的methodRequest*/ public class Scheduler { private LinkedBlockingQueue
           
             requestQueue = new LinkedBlockingQueue
            
             (100); private Dispatcher dispatcher = new Dispatcher(); public Scheduler() { /*启动dispatcher线程（consumer），实际使用中，dispatcher应该会有多个，并使用线程池进行管理，此处简化为1个。*/ new Thread(dispatcher).start(); } /*对外提供的接口，client通过ServiceProxy可并发调用此方法*/ public Future
              enqueue(Callable request) { final FutureTask task = new FutureTask(request); try { requestQueue.put(task); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } return task; } private class Dispatcher implements Runnable { public volatile boolean isRunning = true; @Override public void run() { // TODO Auto-generated method stub while(!Thread.currentThread().isInterrupted() && true == isRunning) { try { FutureTask task = requestQueue.take(); if( null != task ) { task.run(); /*task利用给定的Servant去执行调用，这里引入了Command模式*/ } } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); Thread.currentThread().interrupt(); /*阻塞状态下被中断，中断标志会清掉，需要重新置位一下*/ } } } } } /*模拟执行最终的调用*/ public class Servant { public int getNumberOfCustomers() { return 11; } public double getBalance() { return 0.177; } }}
            
           
          
         
        
       
      
     
    
   

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