【代码积累-1】ActiveObject

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<Integer> getNumberOfCustomers = null;private Future<Double> 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 blocke.printStackTrace();}}public void getBalance() {getBalance = proxy.getBalance();try {System.out.println("Balance = "+getBalance.get());} catch (InterruptedException | ExecutionException e) {// TODO Auto-generated catch blocke.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<Integer> getNumberOfCustomers() {/*生成一个MethodRequest对象，并通过scheduler加入队列。*/MethodRequestGetCustomerNumber request = new MethodRequestGetCustomerNumber(servant);return (Future<Integer>)scheduler.enqueue(request);}public Future<Double> getBalance() {MethodRequestGetBalance request = new MethodRequestGetBalance(servant);return (Future<Double>)scheduler.enqueue(request);}}/*封装客户端的调用*/public abstract class MethodRequestInteger implements Callable<Integer>{protected int requestType = 0;}public abstract class MethodRequestDouble implements Callable<Double>{protected int requestType = 0;}public class MethodRequestGetCustomerNumber extends MethodRequestInteger {private Servant servant = null;public MethodRequestGetCustomerNumber(Servant servant) {super();this.servant = servant;}@Overridepublic Integer call() throws Exception {// TODO Auto-generated method stubreturn servant.getNumberOfCustomers();}}public class MethodRequestGetBalance extends MethodRequestDouble {private Servant servant = null;public MethodRequestGetBalance(Servant servant) {super();this.servant = servant;}@Overridepublic Double call() throws Exception {// TODO Auto-generated method stubreturn servant.getBalance();}}/*维护请求队列，并调用队列中的methodRequest*/public class Scheduler {private LinkedBlockingQueue<FutureTask> requestQueue = new LinkedBlockingQueue<FutureTask>(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 blocke.printStackTrace();}return task;}private class Dispatcher implements Runnable {public volatile boolean isRunning = true;@Overridepublic void run() {// TODO Auto-generated method stubwhile(!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 blocke.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;}}}