spring boot实现超轻量级网关(反向代理、转发)

在我们的rest服务中,需要暴露一个中间件的接口给用户,但是需要经过rest服务的认证,这是典型的网关使用场景。可以引入网关组件来搞定,但是引入zuul等中间件会增加系统复杂性,这里实现一个超轻量级的网关,只实现请求转发,认证等由rest服务的spring security来搞定。

如何进行请求转发呢? 熟悉网络请求的同学应该很清楚,请求无非就是请求方式、HTTP header,以及请求body,我们将这些信息取出来,透传给转发的url即可。

举例:

/graphdb/** 转发到 Graph_Server/**

获取转发目的地址:#

Copy
private String createRedictUrl(HttpServletRequest request, String routeUrl, String prefix) {
        String queryString = request.getQueryString();
        return routeUrl + request.getRequestURI().replace(prefix, "") +
                (queryString != null ? "?" + queryString : "");
    }

解析请求头和内容#

然后从request中提取出header、body等内容,构造一个RequestEntity,后续可以用RestTemplate来请求。

Copy
private RequestEntity 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));
    }


    private byte[] parseRequestBody(HttpServletRequest request) throws IOException {
        InputStream inputStream = request.getInputStream();
        return StreamUtils.copyToByteArray(inputStream);
    }

    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;
    }

透明转发#

最后用RestTemplate来实现请求:

Copy
 private ResponseEntity<String> route(RequestEntity requestEntity) {
        RestTemplate restTemplate = new RestTemplate();
        return restTemplate.exchange(requestEntity, String.class);
    }

全部代码#

以下是轻量级转发全部代码:

Copy
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;

@Service
public class RoutingDelegate {


    public ResponseEntity<String> redirect(HttpServletRequest request, HttpServletResponse response,String routeUrl, String prefix) {
        try {
            // build up the redirect URL
            String redirectUrl = createRedictUrl(request,routeUrl, prefix);
            RequestEntity requestEntity = createRequestEntity(request, redirectUrl);
            return route(requestEntity);
        } catch (Exception e) {
            return new ResponseEntity("REDIRECT ERROR", HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    private String createRedictUrl(HttpServletRequest request, String routeUrl, String prefix) {
        String queryString = request.getQueryString();
        return routeUrl + request.getRequestURI().replace(prefix, "") +
                (queryString != null ? "?" + queryString : "");
    }


    private RequestEntity 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));
    }
	
    private ResponseEntity<String> route(RequestEntity requestEntity) {
        RestTemplate restTemplate = new RestTemplate();
        return restTemplate.exchange(requestEntity, String.class);
    }


    private byte[] parseRequestBody(HttpServletRequest request) throws IOException {
        InputStream inputStream = request.getInputStream();
        return StreamUtils.copyToByteArray(inputStream);
    }

    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;
    }
}

Spring 集成#

Spring Controller,RequestMapping里把GET \ POST\PUT\DELETE 支持的请求带上,就能实现转发了。

Copy
@RestController
@RequestMapping(GraphDBController.DELEGATE_PREFIX)
@Api(value = "GraphDB", tags = {
        "graphdb-Api"
})
public class GraphDBController {

    @Autowired
    GraphProperties graphProperties;

    public final static String DELEGATE_PREFIX = "/graphdb";

    @Autowired
    private RoutingDelegate routingDelegate;

    @RequestMapping(value = "/**", method = {RequestMethod.GET, RequestMethod.POST, RequestMethod.PUT, RequestMethod.DELETE}, produces = MediaType.TEXT_PLAIN_VALUE)
    public ResponseEntity catchAll(HttpServletRequest request, HttpServletResponse response) {
        return routingDelegate.redirect(request, response, graphProperties.getGraphServer(), DELEGATE_PREFIX);
    }
}


 

https://www.cnblogs.com/xiaoqi/p/spring-boot-route.html

posted @ 2020-11-18 16:10  沧海一滴  阅读(423)  评论(0编辑  收藏