我有一個調用HTTPGET得到HTML輸出相當簡單HttpClient的4碼。 HTML返回的腳本和圖像位置全部設置爲本地（例如<img src="/images/foo.jpg"/>），所以我需要調用URL以將它們設置爲絕對（<img src="http://foo.com/images/foo.jpg"/>）現在問題出現了 - 在調用期間可能會有一兩個302重定向，因此原始URL是不再反映HTML的位置。HttpClient的4 - 如何捕捉最後重定向URL
我怎麼給所有的重定向我可能（或沒有）返回的內容的最新網址是什麼？
我看着HttpGet#getAllHeaders()和HttpResponse#getAllHeaders() - 找不到任何東西。
編輯：HttpGet#getURI()返回原始調用地址
這將是當前的URL，您可以通過調用
編輯得到：你沒有提到你是怎麼做的重定向。這對我們很有用，因爲我們自己處理302。
聽起來你正在使用DefaultRedirectHandler。我們曾經這樣做過。獲取當前URL有點棘手。你需要使用你自己的上下文。以下是相關的代碼片段，
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());
默認重定向並沒有爲我們工作，所以我們改變了，但我忘了是什麼問題。
在2.3版的Android仍然不支持以下重定向（HTTP代碼302）。我剛剛閱讀位置標題並再次下載：
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;
}
}
此處沒有循環重定向保護，所以要小心。更多關於通過博客Follow 302 redirects with AndroidHttpClient
我認爲更容易找到一個網址的方式是使用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;
}
}
代碼使用這個處理程序：
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();
}
最新版本的HttpClient中不推薦使用HttpClient＃setRedirectHandler（）方法。 – 2012-08-24 02:25:01
有誰知道如何在最新版本中處理這個問題？ – 2016-08-08 17:34:55
一個恕我直言，改進方法基於ZZ編碼器的解決方案是使用一個ResponseInterceptor簡單地跟蹤過去的重定向位置。這樣你就不會丟失信息，例如在標籤後面。沒有響應攔截器，你會失去hashtag。例如：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";
使用它，就像ZZ編碼器的解決方案：
HttpResponse response = httpClient.execute(httpGet, context);
String url = getUrlAfterRedirects(context);
這是我設法得到重定向URL：
Header[] arr = httpResponse.getHeaders("Location");
for (Header head : arr){
String whatever = arr.getValue();
}
或者，如果你確信只有一個重定向位置，請執行此操作：
httpResponse.getFirstHeader("Location").getValue();
這對我不起作用。它僅返回最後一個請求的標題。 – 2013-07-18 21:39:20
在HttpClient的4，如果使用的是LaxRedirectStrategy或DefaultRedirectStrategy任何亞類，這是推薦的方法（見的DefaultRedirectStrategy源代碼）：
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);
}
由於HttpClient的版本4.3.x，上面的代碼可以簡化爲：
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);
}
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);
}
其他需要注意的（帶有所有這些答案）是「[原子HTTP重定向處理]（https://fetch.spec.whatwg.org/#atomic-http-redirect-handling）」的概念，這表明出於安全目的，客戶端（至少某些類型的網絡應用程序）不應該能夠看到除最後一個重定向URL之外的任何內容。 （但是，在Java中可能很難完全防止它）。 – 2015-10-02 12:19:56
我發現這對HttpComponents Client Documentation
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();
}
唉，它不會 - getURI（）返回原始調用URL – Bostone 2009-09-21 22:17:15
請參閱我的編輯.................. – 2009-09-22 00:55:23
我不做任何特別的事情 - 非常基本HttpGet代碼。我谷歌我的問題我想我需要禁用自動重定向和「跟蹤線索」，直到我得到200 – Bostone 2009-09-22 01:19:59