远程调用模拟-用Socket实现与RMI的形式的对比
远程调用其实没有想象地那么复杂，当然，性能好的RPC当然需要仔细设计，那么最基础的理解什么是RPC呢？从本DEMO看起：
暴露的服务：等待远程来调用。客户端在调用前需要来绑定生成个代理，类似于动态代理模式
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();
new Thread(new Runnable() {
@Override
public void run() {
try {
try {
ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
try {
String methodName = input.readUTF();
Class<?>[] parameterTypes = (Class<?>[])input.readObject();
Object[] arguments = (Object[])input.readObject();
ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
try {
Method method = service.getClass().getMethod(methodName, parameterTypes);
Object result = method.invoke(service, arguments);
output.writeObject(result);
} 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
*/
@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();
}
}
});
}
}
调用的接口：
/**
* HelloService
*
* @author william.liangf
*/
public interface HelloService {
String hello(String name);
String cry(String name,int minutes);
}
接口的实现：
/**
* HelloServiceImpl
*
* @author william.liangf
*/
public class HelloServiceImpl implements HelloService {
public String hello(String name) {
return "Hello " + name;
}
@Override
public String cry(String name,int minutes) {
// TODO Auto-generated method stub
return "Cry " + name+"minutes"+minutes;
}
}
消费者：
/**
* RpcConsumer
*
* @author william.liangf
*/
public class RpcConsumer {
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);
if (i==2||i==1) {
String Cry = service.cry("CryCryCry" + i,i);
System.out.println(Cry);
}
Thread.sleep(1000);
}
}
}
提供者：
/**
* RpcProvider
*
* @author william.liangf
*/
public class RpcProvider {
public static void main(String[] args) throws Exception {
HelloService service = new HelloServiceImpl();
RpcFramework.export(service, 1234);
}
}
从代码中可以看出，该RPC调用的核心是SOCKET通信。
然后往Socket里写Object,轻松理解RPC
------------------------------------------------------------------------我是分割线
那么对比下另外一种远程调用：rmi
服务的接口
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface AddServer extends Remote {
public int AddNumbers(int firstnumber,int secondnumber) throws RemoteException;
}
服务的实现
public class AddServerImpl extends UnicastRemoteObject implements AddServer {
public AddServerImpl() throws RemoteException {
super();
}
public int AddNumbers(int firstnumber,int secondnumber) throws RemoteException {
return firstnumber + secondnumber;
}
}
远程RMI的具体服务：
import java.rmi.Naming;
import java.rmi.registry.LocateRegistry;
public class RmiServer {
/**
* 启动 RMI 注册服务并进行对象注册
*/
public static void main(String[] argv)
{
try
{
//启动RMI注册服务，指定端口为1099 （1099为默认端口）
//也可以通过命令 ＄java_home/bin/rmiregistry 1099启动
//这里用这种方式避免了再打开一个DOS窗口
//而且用命令rmiregistry启动注册服务还必须事先用RMIC生成一个占位程序(stub类)为它所用
LocateRegistry.createRegistry(1099);
//创建远程对象的一个或多个实例，下面是hello对象
//可以用不同名字注册不同的实例
AddServer add = new AddServerImpl();
//把hello注册到RMI注册服务器上，命名为Hello
Naming.rebind("Hello", add);
//如果要把hello实例注册到另一台启动了RMI注册服务的机器上
//Naming.rebind("//192.168.1.105:1099/Hello",hello);
System.out.println("Hello Server is ready.");
}
catch (Exception e)
{
System.out.println("Hello Server failed: " + e);
}
}
}
客户端：
import java.net.MalformedURLException;
import java.rmi.Naming;
import java.rmi.NotBoundException;
import java.rmi.RemoteException;
import com.gjy.rmi.service.AddServer;
public class RmiClient {
public static void main(String args[]) throws RemoteException, MalformedURLException, NotBoundException {
String url="rmi://127.0.0.1/Hello";
AddServer add;
add = (AddServer)Naming.lookup(url);
int result=0;
for (int i =0;i<10;i++){
result = add.AddNumbers(10,i);
System.out.println(result);
}
}
}
从以上可看出rmi的编码效率远大于socket的形式，节约了非常多的代码。下一遍文章会分析其他的远程调用并对比性能