带有来自 HTTP POST 的响应的 Spring MVC 重定向答案

【问题标题】：Spring MVC Redirect with Response from HTTP POST带有来自 HTTP POST 的响应的 Spring MVC 重定向
【发布时间】：2017-03-15 22:02:17
【问题描述】：

我需要使用 Spring MVC 使用带有已构建对象的 POST 重定向到外部服务。

通过阅读this previous question，我了解到无法通过 Spring MVC 重定向执行此操作，因此需要通过 Java 代码中的 HTTP 客户端完成 POST 请求，我可以通过示例来完成，例如找到here的那个。

我需要能够将浏览器重定向到 POST 请求的响应，但我不确定如何使用 Spring MVC 来做到这一点。

控制器

@RequestMapping(method = RequestMethod.GET, value = "/handoff")
public HttpEntity dispatch(HttpServletRequest request,
  @RequestParam(value = "referralURL", required = false) String referralUrl) {

    String redirectURL = "http://desinationURL.com/post";

    HttpClientHelper httpHelper = new HttpClientHelper();
    HttpEntity entity = httpHelper.httpClientPost(redirectURL, null);

    // Redirect
    return entity;
}

HttpClientHelper.java

public HttpEntity httpClientPost(String url, List<NameValuePair> params) throws ClientProtocolException, IOException {

    HttpClient httpclient = HttpClients.createDefault();
    HttpPost httppost = new HttpPost(url);

    // Request parameters and other properties.
    if (params != null) {
        httppost.setEntity(new UrlEncodedFormEntity(params, Constants.UTF_8_ENCODING));
    }

    // Execute and get the response.
    HttpResponse response = httpclient.execute(httppost);
    HttpEntity entity = response.getEntity();

    return entity;

}

我可以看到目标服务被 POST 请求成功命中，我需要从 MCV 控制器读取响应的输出作为返回值，因为它当前只返回 404。

【问题讨论】：

标签： java spring spring-mvc redirect apache-httpclient-4.x

【解决方案1】：

您不能重定向浏览器响应 POST 请求。您所能做的就是将调用结果发送回外部 URL。或者以某种方式处理响应，然后转发到应用程序中显示有关响应的一些信息的其他页面。

例如

@RequestMapping(method = RequestMethod.GET, value = "/handoff")
public void dispatch(HttpServletRequest request,
  @RequestParam(value = "referralURL", required = false) String referralUrl, HttpServletResponse response) {

    String redirectURL = "http://desinationURL.com/post";

    HttpClientHelper httpHelper = new HttpClientHelper();
    HttpEntity entity = httpHelper.httpClientPost(redirectURL, null);

    //streams the raw response
    entity.writeTo(response.getOutputSStream());
}

【讨论】：

【解决方案2】：

我就是这样做的

    CloseableHttpClient httpClient = HttpClients.custom()
            .setRedirectStrategy(new LaxRedirectStrategy())
            .build();

    //this reads the input stream from POST
    ServletInputStream str = request.getInputStream();

    HttpPost httpPost = new HttpPost(path);
    HttpEntity postParams = new InputStreamEntity(str);
    httpPost.setEntity(postParams);

    HttpResponse httpResponse = null ;
    int responseCode = -1 ;
    StringBuffer response  = new StringBuffer();

    try {

        httpResponse = httpClient.execute(httpPost);

        responseCode = httpResponse.getStatusLine().getStatusCode();
        logger.info("POST Response Status::  {} for file {}  ", responseCode, request.getQueryString());

        //return httpResponse ;
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                httpResponse.getEntity().getContent()));

        String inputLine;
        while ((inputLine = reader.readLine()) != null) {
            response.append(inputLine);
        }
        reader.close();

        logger.info(" Final Complete Response {}  " + response.toString());
        httpClient.close();

    } catch (Exception e) {

        logger.error("Exception ", e);

    } finally {

        IOUtils.closeQuietly(httpClient);

    }

    // Return the response back to caller
    return  new ResponseEntity<String>(response.toString(), HttpStatus.ACCEPTED);

【讨论】：

【解决方案3】：

使用 sendRedirect 而不是 HttpClient，您的控制器方法应如下所示。

@RequestMapping(method = RequestMethod.GET, value = "/handoff")
public HttpEntity dispatch(HttpServletRequest request, HttpServletResponse response,
  @RequestParam(value = "referralURL", required = false) String referralUrl) {

    String redirectURL = "http://desinationURL.com/post";

    response.setStatus(HttpServletResponse.SC_TEMPORARY_REDIRECT);
    response.setHeader("Location", redirectURL);

    // Redirect
    return entity;
}

【讨论】：

我已经包含了 HttpServletResponse 并按照建议设置了状态和标头值，但是它没有重定向，仍然返回 404。我是否需要更改方法以返回响应而不是 HttpEntity？

【解决方案4】：

如果您对更复杂的解决方案感兴趣，您可以利用 Zuul 并让 zuul 管理请求转发。 https://github.com/Netflix/zuul 在过滤器链中，您可以随心所欲地操纵请求。

【讨论】：