自己手动写一个RPC框架

一，简单一点的过程解说图（不太清晰，凑合看吧）

Gitee仓库源码：https://gitee.com/fanjiangfeng/write-rpc-framwork

common模块
- 创建商品实体类和查询接口
RPC框架
- 创建一个注册中心（key：接口全名，value：实现类全名）
- 创建RpcRequest，装载信息，也要序列化，也是网络传输的一员
- 创建RpcServer，用来创建serversocket，接收client发来的内容【RpcRequest对象，从注册中心中根据key取出实现类class，然后根据参数和方法名利用反射来执行，返回执行结果】
client端
- 直接调用Rpc框架的创建代理类方法，得到返回值
server端
- 写一个common接口的实现类
- 把实现类注册到注册中心上
- 调用RpcServer开启socketserver，接收RpcRequest，根据注册中心的key，value得到实现类的class，并解析器中的参数&&执行方法&&返回

二，代码实现

1，rpc-common模块

新建Product类，记得实现序列化，因为要在网络中进行传输。

public class Product implements Serializable {
    private String name;
    private Integer price;
	//...
}

新建查询的接口

public interface ProductService {
    Product getById(Integer id);
}

2，rpc-framwork框架

首先一个注册中心，简单点，一个Map搞定

public class Registry {
    public static HashMap<String,Class> map = new HashMap<String,Class>();
}

创建RpcRequest，装载信息，也要序列化，也是网络传输的一员。

public class RpcRequest implements Serializable {
    private String className;
    private String methodName;
    private Class[] types;
    private Object[] params;
    //...
}

RpcServer，用来创建serversocket，接收client发来的内容（此处线程池只是用来提高效率）

public class RPCServer {
    ExecutorService service = Executors.newFixedThreadPool(5);
    public void provide(int port){
        try {
            ServerSocket serverSocket = new ServerSocket(port);
            while (true){
                Socket socket = serverSocket.accept();
                service.execute(new ProcessHandler(socket));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

ProcessHandler实现Runbale，重写run方法，写核心逻辑

public class ProcessHandler implements Runnable {
    private Socket socket;
    public ProcessHandler(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        ObjectInputStream inputStream = null;
        ObjectOutputStream outputStream = null;
        //核心逻辑
        try {
            //解析消息
            inputStream = new ObjectInputStream(socket.getInputStream());
            RpcRequest rpcRequest = (RpcRequest) inputStream.readObject();
            //反射
            Class clazz = null;
            //判断注册中心是否存在接口
            if(Registry.map.containsKey(rpcRequest.getClassName())){
                clazz = Registry.map.get(rpcRequest.getClassName());
            }
            Method method = clazz.getMethod(rpcRequest.getMethodName(), rpcRequest.getTypes());
            Object result = method.invoke(clazz.newInstance(),rpcRequest.getParams());
            //返回结果
            outputStream = new ObjectOutputStream(socket.getOutputStream());
            outputStream.writeObject(result);
            outputStream.flush();

        }catch (Exception e){

        }finally {
            //关闭流
            try {
                if(inputStream!=null)inputStream.close();
                if(outputStream!=null)outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

创建RpcProxy类，用于创建接口的动态代理

public class RpcProxy<T> {
    public T remoteCall(String host,int port,Class interfaces){
        //动态代理
        return (T)Proxy.newProxyInstance(interfaces.getClassLoader(),new Class[]{interfaces},new RemoteInvocationHandler(host,port,interfaces));
    }
}

创建RemoteInvocationHandler（自定义的名称），重写invoke方法，写代理类要执行的逻辑。

public class RemoteInvocationHandler implements InvocationHandler {
    private String host;
    private int port;
    private Class interfaces;

    public RemoteInvocationHandler(String host, int port, Class interfaces) {
        this.host = host;
        this.port = port;
        this.interfaces = interfaces;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) {
        //核心逻辑

        //封装消息体
        RpcRequest rpcRequest = new RpcRequest();
        rpcRequest.setClassName(interfaces.getName());
        rpcRequest.setMethodName(method.getName());
        rpcRequest.setTypes(method.getParameterTypes());
        rpcRequest.setParams(args);

        Object result = null;
        ObjectInputStream inputStream = null;
        ObjectOutputStream outputStream = null;
        try {
            Socket socket = new Socket(host, port);

            //发送消息
            outputStream = new ObjectOutputStream(socket.getOutputStream());
            outputStream.writeObject(rpcRequest);
            outputStream.flush();

            //接收结果
            inputStream = new ObjectInputStream(socket.getInputStream());
            result = inputStream.readObject();

        }catch (Exception e){

        }finally {
            //关闭流
            try {
                if(inputStream!=null)inputStream.close();
                if(outputStream!=null)outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    }
}

3，rpc-server模块

写一个ProductService接口的实现类的具体逻辑

public class ProductServiceImpl implements ProductService {

    @Override
    public Product getById(Integer id) {
        Product product = new Product();
        product.setName("感冒灵");
        product.setPrice(10);
        return product;
    }
}

然后把接口和实现类注册到RPC的注册中心，然后通过RPC的RPCServer开启一个serversocket，监听某一个端口。

public class Server {
    public static void main(String[] args) {
        Registry.map.put(ProductService.class.getName(),ProductServiceImpl.class);
        new RPCServer().provide(9000);
    }
}

4，rpc-client模块

直接发起对rpc-server的调用

public class Client {
    public static void main(String[] args) {
        RpcProxy rpcProxy = new RpcProxy();
        ProductService service = (ProductService) rpcProxy.remoteCall("localhost",9000,ProductService.class);
        System.out.println(service.getById(10).toString());
    }
}