spring boot實現超輕量級網關（反向代理、轉發）

在我們的rest服務中，需要暴露一個中間件的接口給用戶，但是需要經過rest服務的認證，這是典型的網關使用場景。可以引入網關組件來搞定，但是引入zuul等中間件會增加系統復雜性，這里實現一個超輕量級的網關，只實現請求轉發，認證等由rest服務的spring security來搞定。

如何進行請求轉發呢？ 熟悉網絡請求的同學應該很清楚，請求無非就是請求方式、HTTP header，以及請求body，我們將這些信息取出來，透傳給轉發的url即可。

舉例：

/graphdb/** 轉發到 Graph_Server/**

獲取轉發目的地址：#

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

解析請求頭和內容#

然后從request中提取出header、body等內容，構造一個RequestEntity，后續可以用RestTemplate來請求。

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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; } 

透明轉發#

最后用RestTemplate來實現請求：

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

全部代碼#

以下是輕量級轉發全部代碼：

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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 支持的請求帶上，就能實現轉發了。

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@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