Java动态代理类(包括客户端服务端使用反射机制来代理的)

 

1.

   package reflection.remotecall;import java.util.Date;public interface IHelloService {public String echo(String msg);public Date getTime();}

 

2.

   package reflection.remotecall.impl;import java.util.Date;import reflection.remotecall.IHelloService;public class HelloServiceImpl implements IHelloService {public String echo(String msg) {return "echo:"+msg;}public Date getTime() {return new Date();}}

 

 

3.  创建一个实现了HelloService 接口的动态代理类的实例 参数 helloService 引用被代理的HelloService 实例

 

   package reflection.proxyfactory;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import reflection.remotecall.IHelloService;import reflection.remotecall.impl.HelloServiceImpl;/** * 创建一个实现了HelloService 接口的动态代理类的实例 参数 helloService 引用被代理的HelloService 实例 */public class HelloServiceProxyFactory {public static IHelloService getHelloServiceProxy(final IHelloService helloService) {// 创建一个实现了InvocationHandler接口的匿名类的实例InvocationHandler handler = new InvocationHandler() {public Object invoke(Object proxy, Method method, Object args[])throws Exception {System.out.println("before calling " + method); // 预处理Object result = method.invoke(helloService, args);// 调用被代理的HelloService 实例的方法System.out.println("after calling " + method); // 事后处理return result;}};Class classType = IHelloService.class;return (IHelloService)Proxy.newProxyInstance(classType.getClassLoader(), new Class[]{classType}, handler);}public static void main(String[] args) {IHelloService helloService = new HelloServiceImpl();IHelloService helloServiceProxy = HelloServiceProxyFactory.getHelloServiceProxy(helloService); System.out.println("动态代理类的名字为: " + helloServiceProxy.getClass().getName());System.out.println(helloServiceProxy.echo("linwei"));}}

 

4. 客户端调用代码

 

   package reflection.client;import java.io.InputStream;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.io.OutputStream;import java.net.Socket;import reflection.util.Call;public class SimpleClient {public void invoke() throws Exception {Socket socket = new Socket("localhost", 8000);OutputStream out = socket.getOutputStream();ObjectOutputStream oos = new ObjectOutputStream(out);InputStream in = socket.getInputStream();ObjectInputStream ois = new ObjectInputStream(in);Call call = new Call("reflection.remotecall.IHelloService","echo",new Class[]{String.class},new Object[]{"Hello"});//向服务器发送Call对象oos.writeObject(call);//接收包含了执行结果的Call对象call = (Call)ois.readObject();System.out.println("结果是: " + call.getResult());ois.close();oos.close();socket.close();}public static void main(String[] args) throws Exception {new SimpleClient().invoke();}}  

 

5.  服务端调用的代码

 

  package reflection.server;import java.io.InputStream;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.io.OutputStream;import java.lang.reflect.Method;import java.net.ServerSocket;import java.net.Socket;import java.util.HashMap;import java.util.Map;import reflection.remotecall.impl.HelloServiceImpl;import reflection.util.Call;public class SimpleServer {//该Map用来存放远程对象的private Map remoteObjects = new HashMap();/* * 把一个远程对象放到缓存中去 */public void register(String className, Object remoteObject) {remoteObjects.put(className, remoteObject);}/** * 远程服务器提供的服务方法 * @throws Exception */public void service() throws Exception {ServerSocket serverSocket = new ServerSocket(8000);System.out.println("服务器已经启动了!");while (true) {Socket socket = serverSocket.accept();InputStream in = socket.getInputStream();//把取到的输入流从新封装成一个 对象输入流ObjectInputStream ois = new ObjectInputStream(in);OutputStream out = socket.getOutputStream();//把获取到的输出流 转化为 对象输出流ObjectOutputStream oos = new ObjectOutputStream(out);//接收客户端发送的Call对象Call call = (Call) ois.readObject();System.out.println("call is " + call);//调用相关对象的执行方法(采用反射机制来调用)call = invoke(call);//向客户端发送包含了执行结果的Call对象oos.writeObject(call);ois.close();oos.close();socket.close();}}public Call invoke(Call call) {Object result = null;try {String className = call.getClassName();String methodName = call.getMethodName();Object[] params = call.getParamValue();Class classType = Class.forName(className);Class[] paramTypes = call.getParamTypes();//通过 方法名字和方法参数类型 来决定调用何种方法Method method = classType.getMethod(methodName, paramTypes);//通过类名，从缓存中取出相关的远程对象Object remoteObject = remoteObjects.get(className);if(remoteObject == null) {throw new Exception(className + "远程对象不存在");} else {result = method.invoke(remoteObject, params);}} catch (Exception e) {e.printStackTrace(); result = e; }call.setResult(result);return call;}public static void main(String[] args) throws Exception {SimpleServer simpleServer = new SimpleServer(); //把事先创建的HelloServiceImpl 对象加入到服务器的缓存中simpleServer.register("reflection.remotecall.IHelloService",new HelloServiceImpl());simpleServer.service();}}