自定义的RPC的Java实现

最新推荐文章于 2024-08-27 10:07:47 发布

wbj0110

最新推荐文章于 2024-08-27 10:07:47 发布

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分类专栏： RPC Java 文章标签： RPC Java

本文链接：https://blog.youkuaiyun.com/wbj0110/article/details/84530022

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在看hadoop的源代码的时候，看到hadoop实现了一个自定义的RPC，于是有了自己写代码实现RPC的想法。

RPC的全名Remote Process Call，即远程过程调用。使用RPC，可以像使用本地的程序一样使用远程服务器上的程序。下面是一个简单的RPC 调用实例，从中可以看到RPC如何使用以及好处：

Java代码

public class MainClient {
public static void main(String[] args) {
Echo echo = RPC.getProxy(Echo.class, "127.0.0.1", 20382);
System.out.println(echo.echo("hello,hello"));
}
}

public class MainClient {
	public static void main(String[] args) {
		Echo echo = RPC.getProxy(Echo.class, "127.0.0.1", 20382);	
		System.out.println(echo.echo("hello,hello"));
	}
}

Java代码

  
   
   
    
     
     Java代码   
     
    
   public interface Echo {  
    public String echo(String string);  
}

public interface Echo {
	public String echo(String string);
}

使用RPC.getProxy生成接口Echo的代理实现类。然后就可以像使用本地的程序一样来调用Echo中的echo方法。

使用RPC的好处是简化了远程服务访问。提高了开发效率。在分发代码时，只需要将接口分发给客户端使用，在客户端看来只有接口，没有具体类实现。这样保证了代码的可扩展性和安全性。

在看了RPCClient如何使用，我们再来定义一个RPC服务器的接口，看看服务器都提供什么操作：

Java代码

public interface Server {
public void stop();
public void start();
public void register(Class interfaceDefiner,Class impl);
public void call(Invocation invo);
public boolean isRunning();
public int getPort();
}

public interface Server {
	public void stop();
	public void start();
	public void register(Class interfaceDefiner,Class impl);
	public void call(Invocation invo);
	public boolean isRunning();
	public int getPort();
}

服务器提供了start和stop方法。使用register注册一个接口和对应的实现类。call方法用于执行Invocation指定的接口的方法名。isRunning返回了服务器的状态，getPort（）则返回了服务器使用的端口。

来看看Invocation的定义：

Java代码

public class Invocation implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
private Class interfaces;
private Method method;
private Object[] params;
private Object result;
/**
* @return the result
*/
public Object getResult() {
return result;
}
/**
* @param result the result to set
*/
public void setResult(Object result) {
this.result = result;
}
/**
* @return the interfaces
*/
public Class getInterfaces() {
return interfaces;
}
/**
* @param interfaces the interfaces to set
*/
public void setInterfaces(Class interfaces) {
this.interfaces = interfaces;
}
/**
* @return the method
*/
public Method getMethod() {
return method;
}
/**
* @param method the method to set
*/
public void setMethod(Method method) {
this.method = method;
}
/**
* @return the params
*/
public Object[] getParams() {
return params;
}
/**
* @param params the params to set
*/
public void setParams(Object[] params) {
this.params = params;
}
@Override
public String toString() {
return interfaces.getName()+"."+method.getMethodName()+"("+Arrays.toString(params)+")";
}
}

public class Invocation implements Serializable{
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	
	private Class interfaces;
	private Method method;
	private Object[] params;
	private Object result;
	
	
	/**
	 * @return the result
	 */
	public Object getResult() {
		return result;
	}
	/**
	 * @param result the result to set
	 */
	public void setResult(Object result) {
		this.result = result;
	}
	/**
	 * @return the interfaces
	 */
	public Class getInterfaces() {
		return interfaces;
	}
	/**
	 * @param interfaces the interfaces to set
	 */
	public void setInterfaces(Class interfaces) {
		this.interfaces = interfaces;
	}
	/**
	 * @return the method
	 */
	public Method getMethod() {
		return method;
	}
	/**
	 * @param method the method to set
	 */
	public void setMethod(Method method) {
		this.method = method;
	}
	/**
	 * @return the params
	 */
	public Object[] getParams() {
		return params;
	}
	/**
	 * @param params the params to set
	 */
	public void setParams(Object[] params) {
		this.params = params;
	}
	@Override
	public String toString() {
		return interfaces.getName()+"."+method.getMethodName()+"("+Arrays.toString(params)+")";
	}
	
}

具体服务器实现类中的call方法是这样使用Invocation的：

Java代码

@Override
public void call(Invocation invo) {
Object obj = serviceEngine.get(invo.getInterfaces().getName()); //根据接口名，找到对应的处理类
if(obj!=null) {
try {
Method m = obj.getClass().getMethod(invo.getMethod().getMethodName(), invo.getMethod().getParams());
Object result = m.invoke(obj, invo.getParams());
invo.setResult(result);
} catch (Throwable th) {
th.printStackTrace();
}
} else {
throw new IllegalArgumentException("has no these class");
}
}

@Override
		public void call(Invocation invo) {
			Object obj = serviceEngine.get(invo.getInterfaces().getName()); //根据接口名，找到对应的处理类
			if(obj!=null) {
				try {
					Method m = obj.getClass().getMethod(invo.getMethod().getMethodName(), invo.getMethod().getParams());
					Object result = m.invoke(obj, invo.getParams());
					invo.setResult(result);
				} catch (Throwable th) {
					th.printStackTrace();
				}
			} else {
				throw new IllegalArgumentException("has no these class");
			}
		}

下面来看服务器接收连接并处理连接请求的核心代码：

Java代码

public class Listener extends Thread {
private ServerSocket socket;
private Server server;
public Listener(Server server) {
this.server = server;
}
@Override
public void run() {
System.out.println("启动服务器中，打开端口" + server.getPort());
try {
socket = new ServerSocket(server.getPort());
} catch (IOException e1) {
e1.printStackTrace();
return;
}
while (server.isRunning()) {
try {
Socket client = socket.accept();
ObjectInputStream ois = new ObjectInputStream(client.getInputStream());
Invocation invo = (Invocation) ois.readObject();
server.call(invo);
ObjectOutputStream oos = new ObjectOutputStream(client.getOutputStream());
oos.writeObject(invo);
oos.flush();
oos.close();
ois.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
if (socket != null && !socket.isClosed())
socket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

public class Listener extends Thread {
	private ServerSocket socket;
	private Server server;

	public Listener(Server server) {
		this.server = server;
	}

	@Override
	public void run() {

		System.out.println("启动服务器中，打开端口" + server.getPort());
		try {
			socket = new ServerSocket(server.getPort());
		} catch (IOException e1) {
			e1.printStackTrace();
			return;
		}
		while (server.isRunning()) {
			try {
				
				Socket client = socket.accept();
				ObjectInputStream ois = new ObjectInputStream(client.getInputStream());
				Invocation invo = (Invocation) ois.readObject();
				server.call(invo);
				ObjectOutputStream oos = new ObjectOutputStream(client.getOutputStream());
				oos.writeObject(invo);
				oos.flush();
				oos.close();
				ois.close();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

		}

		try {
			if (socket != null && !socket.isClosed())
				socket.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

RPC具体的Server类是这样来使用Listener的：

Java代码

public static class RPCServer implements Server{
private int port = 20382;
private Listener listener;
private boolean isRuning = true;
/**
* @param isRuning the isRuning to set
*/
public void setRuning(boolean isRuning) {
this.isRuning = isRuning;
}
/**
* @return the port
*/
public int getPort() {
return port;
}
/**
* @param port the port to set
*/
public void setPort(int port) {
this.port = port;
}
private Map<String ,Object> serviceEngine = new HashMap<String, Object>();
@Override
public void call(Invocation invo) {
System.out.println(invo.getClass().getName());
Object obj = serviceEngine.get(invo.getInterfaces().getName());
if(obj!=null) {
try {
Method m = obj.getClass().getMethod(invo.getMethod().getMethodName(), invo.getMethod().getParams());
Object result = m.invoke(obj, invo.getParams());
invo.setResult(result);
} catch (Throwable th) {
th.printStackTrace();
}
} else {
throw new IllegalArgumentException("has no these class");
}
}
@Override
public void register(Class interfaceDefiner, Class impl) {
try {
this.serviceEngine.put(interfaceDefiner.getName(), impl.newInstance());
System.out.println(serviceEngine);
} catch (Throwable e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void start() {
System.out.println("启动服务器");
listener = new Listener(this);
this.isRuning = true;
listener.start();
}
@Override
public void stop() {
this.setRuning(false);
}
@Override
public boolean isRunning() {
return isRuning;
}
}

public static class RPCServer implements Server{
		private int port = 20382;
		private Listener listener; 
		private boolean isRuning = true;
		
		/**
		 * @param isRuning the isRuning to set
		 */
		public void setRuning(boolean isRuning) {
			this.isRuning = isRuning;
		}

		/**
		 * @return the port
		 */
		public int getPort() {
			return port;
		}

		/**
		 * @param port the port to set
		 */
		public void setPort(int port) {
			this.port = port;
		}

		private Map<String ,Object> serviceEngine = new HashMap<String, Object>();
		
		
		@Override
		public void call(Invocation invo) {
			System.out.println(invo.getClass().getName());
			Object obj = serviceEngine.get(invo.getInterfaces().getName());
			if(obj!=null) {
				try {
					Method m = obj.getClass().getMethod(invo.getMethod().getMethodName(), invo.getMethod().getParams());
					Object result = m.invoke(obj, invo.getParams());
					invo.setResult(result);
				} catch (Throwable th) {
					th.printStackTrace();
				}
			} else {
				throw new IllegalArgumentException("has no these class");
			}
		}

		@Override
		public void register(Class interfaceDefiner, Class impl) {
			try {
				this.serviceEngine.put(interfaceDefiner.getName(), impl.newInstance());
				System.out.println(serviceEngine);
			} catch (Throwable e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} 
		}

		@Override
		public void start() {
			System.out.println("启动服务器");
			listener = new Listener(this);
			this.isRuning = true;
			listener.start();
		}

		@Override
		public void stop() {
			this.setRuning(false);
		}

		@Override
		public boolean isRunning() {
			return isRuning;
		}
		
	}

服务器端代码搞定后，来看看客户端的代码，先看看我们刚开始使用RPC.getProxy方法：

Java代码

public static <T> T getProxy(final Class<T> clazz,String host,int port) {
final Client client = new Client(host,port);
InvocationHandler handler = new InvocationHandler() {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
Invocation invo = new Invocation();
invo.setInterfaces(clazz);
invo.setMethod(new org.jy.rpc.protocal.Method(method.getName(),method.getParameterTypes()));
invo.setParams(args);
client.invoke(invo);
return invo.getResult();
}
};
T t = (T) Proxy.newProxyInstance(RPC.class.getClassLoader(), new Class[] {clazz}, handler);
return t;
}

public static <T> T getProxy(final Class<T> clazz,String host,int port) {
		
		final Client client = new Client(host,port);
		InvocationHandler handler = new InvocationHandler() {
			
			@Override
			public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
				Invocation invo = new Invocation();
				invo.setInterfaces(clazz);
				invo.setMethod(new org.jy.rpc.protocal.Method(method.getName(),method.getParameterTypes()));
				invo.setParams(args);
				client.invoke(invo);
				return invo.getResult();
			}
		};
		T t = (T) Proxy.newProxyInstance(RPC.class.getClassLoader(), new Class[] {clazz}, handler);
		return t;
	}

Client类的代码如下：

Java代码

public class Client {
private String host;
private int port;
private Socket socket;
private ObjectOutputStream oos;
private ObjectInputStream ois;
public String getHost() {
return host;
}
public void setHost(String host) {
this.host = host;
}
public int getPort() {
return port;
}
public void setPort(int port) {
this.port = port;
}
public Client(String host, int port) {
this.host = host;
this.port = port;
}
public void init() throws UnknownHostException, IOException {
socket = new Socket(host, port);
oos = new ObjectOutputStream(socket.getOutputStream());
}
public void invoke(Invocation invo) throws UnknownHostException, IOException, ClassNotFoundException {
init();
System.out.println("写入数据");
oos.writeObject(invo);
oos.flush();
ois = new ObjectInputStream(socket.getInputStream());
Invocation result = (Invocation) ois.readObject();
invo.setResult(result.getResult());
}
}

public class Client {
	private String host;
	private int port;
	private Socket socket;
	private ObjectOutputStream oos;
	private ObjectInputStream ois;

	public String getHost() {
		return host;
	}


	public void setHost(String host) {
		this.host = host;
	}

	public int getPort() {
		return port;
	}
	public void setPort(int port) {
		this.port = port;
	}

	public Client(String host, int port) {
		this.host = host;
		this.port = port;
	}

	public void init() throws UnknownHostException, IOException {
		socket = new Socket(host, port);
		oos = new ObjectOutputStream(socket.getOutputStream());
	}

	public void invoke(Invocation invo) throws UnknownHostException, IOException, ClassNotFoundException {
		init();
		System.out.println("写入数据");
		oos.writeObject(invo);
		oos.flush();
		ois = new ObjectInputStream(socket.getInputStream());
		Invocation result = (Invocation) ois.readObject();
		invo.setResult(result.getResult());
	}

}

至此，RPC的客户端和服务器端代码完成，启动服务器的代码如下：

Java代码

public class Main {
public static void main(String[] args) {
Server server = new RPC.RPCServer();
server.register(Echo.class, RemoteEcho.class);
server.start();
}
}

public class Main {
	public static void main(String[] args) {
		Server server = new RPC.RPCServer();
		server.register(Echo.class, RemoteEcho.class);
		server.start();
	}

}

现在先运行服务器端代码，再运行客户端代码，就可以成功运行。

详细的代码，参考附件的源代码。

在写这个RPC时，没有想太多。在数据串行化上，使用了java的标准io序列化机制，虽然不能跨平台，但是做DEMO还是不错的；另外在处理客户端请求上，使用了ServerSocket，而没有使用ServerSocketChannel这个java nio中的新特性；在动态生成接口的实现类上，使用了java.lang.reflet中的Proxy类。他可以动态创建接口的实现类。

Rpc.rar (17.1 KB)