Http反向代理

java , 评论

前言

背景: 有些时候需要对一些接口进行透传, 由于没有任何逻辑, 我们无需直到请求响应对象到底是什么样的, 原样输入输出即可

实现

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package com.example.corsdemo;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.TextNode;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.*;
import org.springframework.stereotype.Service;
import org.springframework.util.MultiValueMap;
import org.springframework.util.StreamUtils;
import org.springframework.web.client.RestTemplate;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Collections;
import java.util.List;

/**
 * @author cuishiying
 * @date 2022-04-21
 */
@Slf4j
@Service
public class RoutingDelegate {

    public ResponseEntity<JsonNode> redirect(HttpServletRequest request, HttpServletResponse response, String routeUrl,
            String prefix) {
        try {
            String redirectUrl = createRedictUrl(request, routeUrl, prefix);
            RequestEntity<byte[]> requestEntity = createRequestEntity(request, redirectUrl);
            return route(requestEntity);
        }
        catch (Exception e) {
            log.error("RoutingDelegate请求错误, request: {}, err: {}", request, e);
            return new ResponseEntity<>(new TextNode("RoutingDelegate err"), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * @param request 原始请求:
     * http://localhost:7110/eachbot-knowledge-proxy-web/delegate/get/1?name=admin
     * @param routeUrl 代理请求: http://localhost:8088
     * @param prefix 原请求需要截取掉的路径
     * @return 代理完整URL
     */
    private String createRedictUrl(HttpServletRequest request, String routeUrl, String prefix) {
        String queryString = request.getQueryString();
        return routeUrl + request.getRequestURI().replace(prefix, "") + (queryString != null ? "?" + queryString : "");
    }

    /**
     * 代理
     */
    private ResponseEntity<JsonNode> route(RequestEntity<byte[]> requestEntity) {
        RestTemplate restTemplate = new RestTemplate();
        return restTemplate.exchange(requestEntity, JsonNode.class);
    }

    /**
     * 构建请求体
     */
    private RequestEntity<byte[]> createRequestEntity(HttpServletRequest request, String url)
            throws URISyntaxException, IOException {
        String method = request.getMethod();
        HttpMethod httpMethod = HttpMethod.resolve(method);
        MultiValueMap<String, String> headers = parseRequestHeader(request);
        byte[] body = parseRequestBody(request);
        return new RequestEntity<>(body, headers, httpMethod, new URI(url));
    }

    /**
     * 构建请求体
     */
    private byte[] parseRequestBody(HttpServletRequest request) throws IOException {
        InputStream inputStream = request.getInputStream();
        return StreamUtils.copyToByteArray(inputStream);
    }

    /**
     * 构建请求头
     */
    private MultiValueMap<String, String> parseRequestHeader(HttpServletRequest request) {
        HttpHeaders headers = new HttpHeaders();
        List<String> headerNames = Collections.list(request.getHeaderNames());
        for (String headerName : headerNames) {
            List<String> headerValues = Collections.list(request.getHeaders(headerName));
            for (String headerValue : headerValues) {
                headers.add(headerName, headerValue);
            }
        }
        return headers;
    }

}

web

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@RestController
@RequestMapping("/delegate")
public class DelegateController {

    @Resource
    private RoutingDelegate routingDelegate;

    /**
     * // @formatter:off
     * 目标应用URI: /app/user/7
     * 前端完整地址: https://xx.xx.xx.xx/context/delegate/app/user/7
     * 代理目标地址: http://127.0.0.1/app/user/7
     * // @formatter:on
     */
    @RequestMapping(value = "/**", method = { RequestMethod.GET, RequestMethod.POST, RequestMethod.PUT,
            RequestMethod.DELETE, RequestMethod.PATCH })
    public Object delegate(HttpServletRequest request, HttpServletResponse response) {
        ResponseEntity<JsonNode> responseEntity = routingDelegate.redirect(request, response, "http://127.0.0.1",
                "/context/delegate");
        return responseEntity.getBody();
    }

}

最后

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