URLConnection不遵循重定向我不明白为什么JavaHttpURLConnection不会跟随重定向。我使用以下代码来获取本页:import java.net.URL;import java.net.HttpURLConnection;import java.io.InputStream;public class Tester {
public static void main(String argv[]) throws Exception{
InputStream is = null;
try {
String bitlyUrl = "http://bit.ly/4hW294";
URL resourceUrl = new URL(bitlyUrl);
HttpURLConnection conn = (HttpURLConnection)resourceUrl.openConnection();
conn.setConnectTimeout(15000);
conn.setReadTimeout(15000);
conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 6.0; ru; rv:1.9.0.11)
Gecko/2009060215 Firefox/3.0.11 (.NET CLR 3.5.30729)");
conn.connect();
is = conn.getInputStream();
String res = conn.getURL().toString();
if (res.toLowerCase().contains("bit.ly"))
System.out.println("bit.ly is after resolving: "+res);
}
catch (Exception e) {
System.out.println("error happened: "+e.toString());
}
finally {
if (is != null) is.close();
}
}}此外，我得到了以下答复(这似乎是完全正确的！)：GET /4hW294 HTTP/1.1Host: bit.lyConnection: Keep-AliveUser-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; ru-RU; rv:1.9.1.3)
Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729)HTTP/1.1 301 MovedServer: nginx/0.7.42Date: Thu, 10 Dec 2009 20:28:44 GMTContent-Type:
text/html; charset=utf-8Connection: keep-aliveLocation: https://www.myganocafe.com/CafeMacyMIME-Version: 1.0Content-Length: 297不幸的是，res变量包含相同的URL，流包含以下内容(显然，Java的HttpURLConnection不跟随重定向！)：<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><HTML><HEAD><TITLE>Moved</TITLE></HEAD><BODY><H2>Moved</H2>
<A HREF="https://www.myganocafe.com/CafeMacy">The requested URL has moved here.</A><P ALIGN=RIGHT><SMALL>
<I>AOLserver/4.5.1 on http://127.0.0.1:7400</I></SMALL></P></BODY></HTML>
3 回答
蛊毒传说
TA贡献1895条经验 获得超3个赞
慕码人2483693
TA贡献1860条经验 获得超9个赞
URL resourceUrl, base, next;
Map<String, Integer> visited;
HttpURLConnection conn;
String location;
int times;
...
visited = new HashMap<>();
while (true)
{
times = visited.compute(url, (key, count) -> count == null ? 1 : count + 1);
if (times > 3)
throw new IOException("Stuck in redirect loop");
resourceUrl = new URL(url);
conn = (HttpURLConnection) resourceUrl.openConnection();
conn.setConnectTimeout(15000);
conn.setReadTimeout(15000);
conn.setInstanceFollowRedirects(false); // Make the logic below easier to detect redirections
conn.setRequestProperty("User-Agent", "Mozilla/5.0...");
switch (conn.getResponseCode())
{
case HttpURLConnection.HTTP_MOVED_PERM:
case HttpURLConnection.HTTP_MOVED_TEMP:
location = conn.getHeaderField("Location");
location = URLDecoder.decode(location, "UTF-8");
base = new URL(url);
next = new URL(base, location); // Deal with relative URLs
url = next.toExternalForm();
continue;
}
break;
}
is = conn.openStream();
...
largeQ
TA贡献2039条经验 获得超8个赞
HttpURLConnection.setFollowRedirects(false)
conn.setInstanceFollowRedirects(true);
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