SpringBoot报文转发

SpringBoot仿Zuul报文转发

基于RestTemplate从request中提取出header、body等内容，构造一个RequestEntity，后续可以用RestTemplate来发送请求

请求入口RestController

public final static String DELEGATE_PREFIX = "/api";

public final static String TARGET_URL = "http://hlooc.cn";

@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, TARGET_URL, DELEGATE_PREFIX);

报文处理RoutingDelegate

    private static final Logger logger = LoggerFactory.getLogger(RoutingDelegate.class);


    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) {
            logger.error("处理异常:{}",e.getLocalizedMessage(),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 route(RequestEntity requestEntity) {
        RestTemplate restTemplate = new RestTemplate();
// 乱码处理
//        List<HttpMessageConverter<?>> messageConverters = restTemplate.getMessageConverters();
//        for (HttpMessageConverter<?> messageConverter : messageConverters) {
//            if (messageConverter instanceof StringHttpMessageConverter) {
//                ((StringHttpMessageConverter) messageConverter).setDefaultCharset(StandardCharsets.UTF_8);
//            }
//        }
        return restTemplate.exchange(requestEntity, Resource.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;
    }

restTemplate.exchange(requestEntity, Resource.class);使用Resource可以解决以下异常:

Could not extract response: no suitable HttpMessageConverter found for response type [class java.lang.Object] and content type [application/octet-stream;charset=GBK]