手撸一个java网关框架

手写一个简易的Java网关框架涉及到很多方面，但我会提供一个基本的框架概念和代码示例，帮助你理解网关的基本构建。以下是一个简单的Java网关框架的实现：

定义路由：需要一个路由表来映射请求的URL到对应的处理器。

请求处理：创建一个请求处理器接口，所有的请求处理类都实现这个接口。

网关服务器：创建一个服务器，监听端口，接收请求，并根据路由表将请求分发到对应的处理器。

步骤1: 定义路由和处理器接口

java

复制

import java.util.HashMap;

import java.util.Map;

// 定义一个简单的路由表

public class Router {

private Map<String, RequestHandler> routes = new HashMap<>();

public void addRoute(String path, RequestHandler handler) {
    routes.put(path, handler);
}

public RequestHandler getHandler(String path) {
    return routes.get(path);
}

}

// 请求处理器接口

public interface RequestHandler {

void handleRequest(Request request, Response response);

}

// 请求和响应对象

public class Request {

// 模拟请求对象

}

public class Response {

private int statusCode;

private String body;

public void setStatusCode(int statusCode) {
    this.statusCode = statusCode;
}

public void setBody(String body) {
    this.body = body;
}

}

步骤2: 实现具体的请求处理器

java

复制

public class HelloHandler implements RequestHandler {

@Override

public void handleRequest(Request request, Response response) {

response.setStatusCode(200);

response.setBody("Hello, this is a simple gateway!");

}

}

步骤3: 创建网关服务器

java

复制

import java.io.*;

import java.net.ServerSocket;

import java.net.Socket;

public class GatewayServer {

private int port;

private Router router;

public GatewayServer(int port) {
    this.port = port;
    this.router = new Router();
    // 添加路由
    router.addRoute("/hello", new HelloHandler());
}

public void start() throws IOException {
    try (ServerSocket serverSocket = new ServerSocket(port)) {
        System.out.println("Server is running on port " + port);
        while (true) {
            Socket socket = serverSocket.accept();
            new Thread(new RequestHandlerThread(socket)).start();
        }
    }
}

private class RequestHandlerThread implements Runnable {
    private Socket socket;

    public RequestHandlerThread(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
             BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()))) {
            
            String line;
            while ((line = reader.readLine()) != null) {
                if (line.isEmpty()) {
                    break;
                }
                String path = line.split(" ")[1]; // 简单解析请求行
                RequestHandler handler = router.getHandler(path);
                if (handler != null) {
                    Request request = new Request(); // 这里需要根据实际情况解析请求
                    Response response = new Response();
                    handler.handleRequest(request, response);
                    writer.write("HTTP/1.1 " + response.getStatusCode() + "\r\n");
                    writer.write("Content-Length: " + response.getBody().length() + "\r\n");
                    writer.write("\r\n");
                    writer.write(response.getBody());
                } else {
                    writer.write("HTTP/1.1 404 Not Found\r\n");
                    writer.write("Content-Length: 0\r\n");
                    writer.write("\r\n");
                }
                writer.flush();
                break;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public static void main(String[] args) {
    try {
        new GatewayServer(8080).start();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

}

这个示例提供了一个非常基础的网关框架，它能够处理HTTP请求并根据路由表分发请求到相应的处理器。请注意，这个示例非常简化，没有实现HTTP协议的全部特性，也没有错误处理和安全性考虑。在实际开发中，你需要根据具体需求扩展和完善这个框架。