处理 HttpClient 重定向

Question

我正在将一些数据发布到响应 302 Moved Temporarily 的服务器。

我希望 HttpClient 遵循重定向并自动获取新位置，因为我相信这是 HttpClient 的默认行为。但是，我遇到了一个异常并且没有遵循重定向:(

这是相关的代码，任何想法将不胜感激：

HttpParams httpParams = new BasicHttpParams();
HttpClientParams.setRedirecting(httpParams, true);
SchemeRegistry schemeRegistry = registerFactories();
ClientConnectionManager clientConnectionManager = new ThreadSafeClientConnManager(httpParams, schemeRegistry);

HttpClient httpClient = new DefaultHttpClient(clientConnectionManager, httpParams)
HttpPost postRequest = new HttpPost(url);
postRequest.setHeader(HTTP.CONTENT_TYPE, contentType);
postRequest.setHeader(ACCEPT, contentType);

if (requestBodyString != null) {
    postRequest.setEntity(new StringEntity(requestBodyString));
}

return httpClient.execute(postRequest, responseHandler);

Answer 1

对于 HttpClient 4.3：

HttpClient instance = HttpClientBuilder.create()
                     .setRedirectStrategy(new LaxRedirectStrategy()).build();

对于 HttpClient 4.2：

DefaultHttpClient client = new DefaultHttpClient();
client.setRedirectStrategy(new LaxRedirectStrategy());

对于 HttpClient ：

DefaultHttpClient client = new DefaultHttpClient();
client.setRedirectStrategy(new DefaultRedirectStrategy() {
    /** Redirectable methods. */
    private String[] REDIRECT_METHODS = new String[] { 
        HttpGet.METHOD_NAME, HttpPost.METHOD_NAME, HttpHead.METHOD_NAME 
    };

    @Override
    protected boolean isRedirectable(String method) {
        for (String m : REDIRECT_METHODS) {
            if (m.equalsIgnoreCase(method)) {
                return true;
            }
        }
        return false;
    }
});

Answer 2

HttpClient 的默认行为符合 HTTP 规范 (RFC 2616) 的要求

10.3.3 302 找到 ... 如果收到 302 状态代码以响应其他请求 与 GET 或 HEAD 相比，用户代理不能自动重定向 请求，除非它可以被用户确认，因为这可能 更改发出请求的条件。

您可以通过继承 DefaultRedirectStrategy 并覆盖其#isRedirected() 方法来覆盖 HttpClient 的默认行为。

Answer 3

默认情况下似乎禁用了 http 重定向。我尝试启用，它可以工作，但我的问题仍然存在错误。但是我们仍然可以务实地处理重定向。我认为你的问题可以解决： 这么老的代码：

AndroidHttpClient httpClient = AndroidHttpClient.newInstance("User-Agent");
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpGet);
long contentSize = httpResponse.getEntity().getContentLength();

如果发生 http 重定向，此代码将返回 contentSize = -1

然后我在尝试启用默认跟随重定向后自己处理重定向

AndroidHttpClient client;
HttpGet httpGet;
HttpResponse response;
HttpHeader httpHeader;
private void handleHTTPRedirect(String url) throws IOException {
    if (client != null)
        client.close();

    client = AndroidHttpClient.newInstance("User-Agent");
    httpGet = new HttpGet(Network.encodeUrl(url));
    response = client.execute(httpGet);
    httpHeader = response.getHeaders("Location");
    while (httpHeader.length > 0) {
        client.close();
        client = AndroidHttpClient.newInstance("User-Agent");

        httpGet = new HttpGet(Network.encodeUrl(httpHeader[0].getValue()));
        response = client.execute(httpGet);
        httpHeader = response.getHeaders("Location");
    }
}

使用中

handleHTTPRedirect(url);
long contentSize = httpResponse.getEntity().getContentLength();

谢谢 阮

Answer 4

我的解决方案是使用 HttClient。我不得不将响应发回给调用者。这是我的解决方案

    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);