HttpClient 4 - 如何捕获上次重定向URL

I have rather simple HttpClient 4 code that calls HttpGet to get HTML output. The HTML returns with scripts and image locations all set to local (e.g. <img src="/images/foo.jpg"/>) so I need calling URL to make these into absolute (<img src="http://foo.com/images/foo.jpg"/>) Now comes the problem - during the call there may be one or two 302 redirects so the original URL is no longer reflects the location of HTML.

我有一个相当简单的HttpClient 4代码，它调用HttpGet来获取HTML输出。 HTML返回脚本和图像位置全部设置为本地（例如）所以我需要调用URL使这些成为绝对（

How do I get the latest URL of the returned content given all the redirects I may (or may not) have?

给定我可能（或可能没有）的所有重定向，如何获取返回内容的最新URL？

I looked at HttpGet#getAllHeaders() and HttpResponse#getAllHeaders() - couldn't find anything.

我查看了HttpGet＃getAllHeaders（）和HttpResponse＃getAllHeaders（） - 找不到任何东西。

Edited: HttpGet#getURI() returns original calling address

编辑：HttpGet＃getURI（）返回原始呼叫地址

8 个解决方案

#1

That would be the current URL, which you can get by calling

这将是当前的URL，您可以通过调用获得

  HttpGet#getURI();

EDIT: You didn't mention how you are doing redirect. That works for us because we handle the 302 ourselves.

编辑：你没有提到你是如何进行重定向的。这对我们有用，因为我们自己处理302。

Sounds like you are using DefaultRedirectHandler. We used to do that. It's kind of tricky to get the current URL. You need to use your own context. Here are the relevant code snippets,

听起来像是在使用DefaultRedirectHandler。我们曾经这样做过。获取当前URL非常棘手。您需要使用自己的上下文。以下是相关的代码片段，

        HttpGet httpget = new HttpGet(url);
        HttpContext context = new BasicHttpContext(); 
        HttpResponse response = httpClient.execute(httpget, context); 
        if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK)
            throw new IOException(response.getStatusLine().toString());
        HttpUriRequest currentReq = (HttpUriRequest) context.getAttribute( 
                ExecutionContext.HTTP_REQUEST);
        HttpHost currentHost = (HttpHost)  context.getAttribute( 
                ExecutionContext.HTTP_TARGET_HOST);
        String currentUrl = (currentReq.getURI().isAbsolute()) ? currentReq.getURI().toString() : (currentHost.toURI() + currentReq.getURI());

The default redirect didn't work for us so we changed but I forgot what was the problem.

默认重定向对我们没有用，所以我们改了但是我忘记了问题所在。

#2

In HttpClient 4, if you are using LaxRedirectStrategy or any subclass of DefaultRedirectStrategy, this is the recommended way (see source code of DefaultRedirectStrategy) :

在HttpClient 4中，如果您使用LaxRedirectStrategy或DefaultRedirectStrategy的任何子类，这是推荐的方法（请参阅DefaultRedirectStrategy的源代码）：

HttpContext context = new BasicHttpContext();
HttpResult<T> result = client.execute(request, handler, context);
URI finalUrl = request.getURI();
RedirectLocations locations = (RedirectLocations) context.getAttribute(DefaultRedirectStrategy.REDIRECT_LOCATIONS);
if (locations != null) {
    finalUrl = locations.getAll().get(locations.getAll().size() - 1);
}

Since HttpClient 4.3.x, the above code can be simplified as:

从HttpClient 4.3.x开始，上面的代码可以简化为：

HttpClientContext context = HttpClientContext.create();
HttpResult<T> result = client.execute(request, handler, context);
URI finalUrl = request.getURI();
List<URI> locations = context.getRedirectLocations();
if (locations != null) {
    finalUrl = locations.get(locations.size() - 1);
}

#3

    HttpGet httpGet = new HttpHead("<put your URL here>");
    HttpClient httpClient = HttpClients.createDefault();
    HttpClientContext context = HttpClientContext.create();
    httpClient.execute(httpGet, context);
    List<URI> redirectURIs = context.getRedirectLocations();
    if (redirectURIs != null && !redirectURIs.isEmpty()) {
        for (URI redirectURI : redirectURIs) {
            System.out.println("Redirect URI: " + redirectURI);
        }
        URI finalURI = redirectURIs.get(redirectURIs.size() - 1);
    }

#4

An IMHO improved way based upon ZZ Coder's solution is to use a ResponseInterceptor to simply track the last redirect location. That way you don't lose information e.g. after an hashtag. Without the response interceptor you lose the hashtag. Example: http://j.mp/OxbI23

基于ZZ Coder解决方案的IMHO改进方法是使用ResponseInterceptor简单地跟踪最后的重定向位置。这样你就不会丢失信息，例如在标签之后。如果没有响应拦截器，则会丢失主题标签。示例：http：//j.mp/OxbI23

private static HttpClient createHttpClient() throws NoSuchAlgorithmException, KeyManagementException {
    SSLContext sslContext = SSLContext.getInstance("SSL");
    TrustManager[] trustAllCerts = new TrustManager[] { new TrustAllTrustManager() };
    sslContext.init(null, trustAllCerts, new java.security.SecureRandom());

    SSLSocketFactory sslSocketFactory = new SSLSocketFactory(sslContext);
    SchemeRegistry schemeRegistry = new SchemeRegistry();
    schemeRegistry.register(new Scheme("https", 443, sslSocketFactory));
    schemeRegistry.register(new Scheme("http", 80, new PlainSocketFactory()));

    HttpParams params = new BasicHttpParams();
    ClientConnectionManager cm = new org.apache.http.impl.conn.SingleClientConnManager(schemeRegistry);

    // some pages require a user agent
    AbstractHttpClient httpClient = new DefaultHttpClient(cm, params);
    HttpProtocolParams.setUserAgent(httpClient.getParams(), "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:13.0) Gecko/20100101 Firefox/13.0.1");

    httpClient.setRedirectStrategy(new RedirectStrategy());

    httpClient.addResponseInterceptor(new HttpResponseInterceptor() {
        @Override
        public void process(HttpResponse response, HttpContext context)
                throws HttpException, IOException {
            if (response.containsHeader("Location")) {
                Header[] locations = response.getHeaders("Location");
                if (locations.length > 0)
                    context.setAttribute(LAST_REDIRECT_URL, locations[0].getValue());
            }
        }
    });

    return httpClient;
}

private String getUrlAfterRedirects(HttpContext context) {
    String lastRedirectUrl = (String) context.getAttribute(LAST_REDIRECT_URL);
    if (lastRedirectUrl != null)
        return lastRedirectUrl;
    else {
        HttpUriRequest currentReq = (HttpUriRequest) context.getAttribute(ExecutionContext.HTTP_REQUEST);
        HttpHost currentHost = (HttpHost)  context.getAttribute(ExecutionContext.HTTP_TARGET_HOST);
        String currentUrl = (currentReq.getURI().isAbsolute()) ? currentReq.getURI().toString() : (currentHost.toURI() + currentReq.getURI());
        return currentUrl;
    }
}

public static final String LAST_REDIRECT_URL = "last_redirect_url";

use it just like ZZ Coder's solution:

像ZZ Coder的解决方案一样使用它：

HttpResponse response = httpClient.execute(httpGet, context);
String url = getUrlAfterRedirects(context);

#5

I think easier way to find last URL is to use DefaultRedirectHandler.

我认为找到最后一个URL的更简单方法是使用DefaultRedirectHandler。

package ru.test.test;

import java.net.URI;

import org.apache.http.HttpResponse;
import org.apache.http.ProtocolException;
import org.apache.http.impl.client.DefaultRedirectHandler;
import org.apache.http.protocol.HttpContext;

public class MyRedirectHandler extends DefaultRedirectHandler {

    public URI lastRedirectedUri;

    @Override
    public boolean isRedirectRequested(HttpResponse response, HttpContext context) {

        return super.isRedirectRequested(response, context);
    }

    @Override
    public URI getLocationURI(HttpResponse response, HttpContext context)
            throws ProtocolException {

        lastRedirectedUri = super.getLocationURI(response, context);

        return lastRedirectedUri;
    }

}

Code to use this handler:

使用此处理程序的代码：

  DefaultHttpClient httpclient = new DefaultHttpClient();
  MyRedirectHandler handler = new MyRedirectHandler();
  httpclient.setRedirectHandler(handler);

  HttpGet get = new HttpGet(url);

  HttpResponse response = httpclient.execute(get);

  HttpEntity entity = response.getEntity();
  lastUrl = url;
  if(handler.lastRedirectedUri != null){
      lastUrl = handler.lastRedirectedUri.toString();
  }

#6

I found this on HttpComponents Client Documentation

我在HttpComponents客户端文档中找到了这个

CloseableHttpClient httpclient = HttpClients.createDefault();
HttpClientContext context = HttpClientContext.create();
HttpGet httpget = new HttpGet("http://localhost:8080/");
CloseableHttpResponse response = httpclient.execute(httpget, context);
try {
    HttpHost target = context.getTargetHost();
    List<URI> redirectLocations = context.getRedirectLocations();
    URI location = URIUtils.resolve(httpget.getURI(), target, redirectLocations);
    System.out.println("Final HTTP location: " + location.toASCIIString());
    // Expected to be an absolute URI
} finally {
    response.close();
}

#7

In version 2.3 Android still do not support following redirect (HTTP code 302). I just read location header and download again:

在版本2.3 Android中仍然不支持以下重定向（HTTP代码302）。我刚读了位置标题并再次下载：

if (statusCode != HttpStatus.SC_OK) {
    Header[] headers = response.getHeaders("Location");

    if (headers != null && headers.length != 0) {
        String newUrl = headers[headers.length - 1].getValue();
        // call again the same downloading method with new URL
        return downloadBitmap(newUrl);
    } else {
        return null;
    }
}

No circular redirects protection here so be careful. More on by blog Follow 302 redirects with AndroidHttpClient

这里没有循环重定向保护，所以要小心。更多关于博客使用AndroidHttpClient关注302重定向

#8

This is how I managed to get the redirect URL:

这就是我设法获取重定向网址的方法：

Header[] arr = httpResponse.getHeaders("Location");
for (Header head : arr){
    String whatever = arr.getValue();
}

Or, if you are sure that there is only one redirect location, do this:

或者，如果您确定只有一个重定向位置，请执行以下操作：

httpResponse.getFirstHeader("Location").getValue();