Java写一个RPC框架

实现RPC框架的关键在于实现远程过程调用的功能。具体来说，需要完成以下步骤：

1. 定义RPC接口
2. 实现RPC框架
3. 编写客户端和服务端的代码

以下是一个简单的Java实现RPC框架的代码示例：

1. 定义RPC接口

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

2. 实现RPC框架

public class RPCFramework {
    // 暴露服务
    public static void export(Object service, int port) throws Exception {
        ServerSocket server = new ServerSocket(port);
        while (true) {
            Socket socket = server.accept();
            new Thread(() -> {
                try {
                    ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
                    ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
                    String methodName = input.readUTF();
                    Class<?>[] parameterTypes = (Class<?>[]) input.readObject();
                    Object[] args = (Object[]) input.readObject();
                    Method method = service.getClass().getMethod(methodName, parameterTypes);
                    Object result = method.invoke(service, args);
                    output.writeObject(result);
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    try {
                        socket.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }).start();
        }
    }

    // 引用服务
    public static <T> T refer(Class<T> interfaceClass, String host, int port) throws Exception {
        Socket socket = new Socket(host, port);
        ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
        ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
        output.writeUTF(interfaceClass.getName());
        output.writeUTF("sayHello");
        output.writeObject(new Class<?>[]{String.class});
        output.writeObject(new Object[]{"world"});
        Object result = input.readObject();
        return (T) result;
    }
}

3. 编写客户端和服务端的代码

服务端：

public class HelloServiceImpl implements HelloService {
    @Override
    public String sayHello(String name) {
        return "Hello, " + name + "!";
    }
}

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

客户端：

public class Client {
    public static void main(String[] args) throws Exception {
        HelloService helloService = RPCFramework.refer(HelloService.class, "localhost", 1234);
        System.out.println(helloService.sayHello("world"));
    }
}

这样，客户端向服务端发起远程调用后就会得到服务端返回的结果。