学步园

http://javatar.iteye.com/blog/1123915

主要利用socket通信，反射，代理实现类似RMI的RPC框架

首先是框架的代码

package framework;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * RpcFramework
 * 
 * @author william.liangf
 */
public class RpcFramework {

    /**
     * 暴露服务
     * 
     * @param service 服务实现
     * @param port 服务端口
     * @throws Exception
     */
    public static void export(final Object service, int port) throws Exception {
        if (service == null)
            throw new IllegalArgumentException("service instance == null");
        if (port <= 0 || port > 65535)
            throw new IllegalArgumentException("Invalid port " + port);
        System.out.println("Export service " + service.getClass().getName() + " on port " + port);
        ServerSocket server = new ServerSocket(port);
        for(;;) {
            try {
                final Socket socket = server.accept();//服务器端一旦收到消息，就创建一个线程进行处理
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            try {
                                ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
                                try {
                                    String methodName = input.readUTF();//service是服务器端提供服务的对象，但是，要通过获取到的调用方法的名称，参数类型，以及参数来选择对象的方法，并调用。获得方法的名称
                                    Class<?>[] parameterTypes = (Class<?>[])input.readObject();//获得参数的类型
                                    Object[] arguments = (Object[])input.readObject();//获得参数
                                    ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
                                    try {
                                        Method method = service.getClass().getMethod(methodName, parameterTypes);//通过反射机制获得方法
                                        Object result = method.invoke(service, arguments);//通过反射机制获得类的方法，并调用这个方法
                                        output.writeObject(result);//将结果发送
                                    } catch (Throwable t) {
                                        output.writeObject(t);
                                    } finally {
                                        output.close();
                                    }
                                } finally {
                                    input.close();
                                }
                            } finally {
                                socket.close();
                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                }).start();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 引用服务
     * 
     * @param <T> 接口泛型
     * @param interfaceClass 接口类型
     * @param host 服务器主机名
     * @param port 服务器端口
     * @return 远程服务
     * @throws Exception
     *///原理是通过代理，获得服务器端接口的一个“代理”的对象。对这个对象的所有操作都会调用invoke函数，在invoke函数中，是将被调用的函数名，参数列表和参数发送到服务器，并接收服务器处理的结果
    @SuppressWarnings("unchecked")
    public static <T> T refer(final Class<T> interfaceClass, final String host, final int port) throws Exception {
        if (interfaceClass == null)
            throw new IllegalArgumentException("Interface class == null");
        if (! interfaceClass.isInterface())
            throw new IllegalArgumentException("The " + interfaceClass.getName() + " must be interface class!");
        if (host == null || host.length() == 0)
            throw new IllegalArgumentException("Host == null!");
        if (port <= 0 || port > 65535)
            throw new IllegalArgumentException("Invalid port " + port);
        System.out.println("Get remote service " + interfaceClass.getName() + " from server " + host + ":" + port);
        return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class<?>[] {interfaceClass}, new InvocationHandler() {
            public Object invoke(Object proxy, Method method, Object[] arguments) throws Throwable {
                Socket socket = new Socket(host, port);
                try {
                    ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
                    try {
                        output.writeUTF(method.getName());
                        output.writeObject(method.getParameterTypes());
                        output.writeObject(arguments);
                        ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
                        try {
                            Object result = input.readObject();
                            if (result instanceof Throwable) {
                                throw (Throwable) result;
                            }
                            return result;
                        } finally {
                            input.close();
                        }
                    } finally {
                        output.close();
                    }
                } finally {
                    socket.close();
                }
            }
        });
    }

}

服务接口

package user;

public interface  HelloService {
	String hello(String name);
}

实现服务

package user;

public class HelloServiceImpl implements HelloService{
	public String hello(String name) {
		return "Hello " + name;
	}

}

服务器

package user;
import framework.RpcFramework;

public class Server {
	public static void main(String []args) throws Exception {
		HelloService service = new HelloServiceImpl();
		RpcFramework.export(service, 1234); 
	}
}

客户机

package user;
import framework.RpcFramework;

public class Client {
	public static void main(String[] args) throws Exception {  
        HelloService service = RpcFramework.refer(HelloService.class, "127.0.0.1", 1234);  
        for (int i = 0; i < Integer.MAX_VALUE; i ++) {  
            String hello = service.hello("World" + i);  
            System.out.println(hello);  
            Thread.sleep(1000);  
        }  
    }  
}

javac framework/RpcFramework.java 

javac -classpath . user/*.java

java -classpath . user.Server

java -classpath . user.Client