获取“java.net.ProtocolException：服务器重定向次数太多”错误 [英] Getting "java.net.ProtocolException: Server redirected too many times" Error

问题描述

我正在使用以下代码制作简单的网址请求：

I'm making a simple URL request with code like this:

URL url = new URL(webpage);
URLConnection urlConnection = url.openConnection();
InputStream is = urlConnection.getInputStream();

但是在最后一行，我得到了重定向太多次错误。如果我的网页var是google.com，那么它可以正常工作，但是当我尝试使用我的servlet的URL时，它就失败了。我似乎可以调整重定向遵循的次数（默认为20）：

But on that last line, I'm getting the "redirected too many times error". If my "webpage" var is, say, google.com then it works fine, but when I try to use my servlet's URL then it fails. It seems I can adjust the number of times it follows the redirects (default is 20) with this:

System.setProperty("http.maxRedirects", "100");

但当我把它调到100时，它肯定需要更长时间才能抛出错误所以我知道它正在努力。但是，我的servlet的URL在（任何）浏览器中工作正常并且在firebug中使用persist选项它似乎只重定向一次。

But when I crank it up to, say, 100 it definitely takes longer to throw the error so I know it is trying. However, the URL to my servlet works fine in (any) browser and using the "persist" option in firebug it seems to only be redirecting once.

更多信息在我的servlet上...它在tomcat中运行，并使用'mod-proxy-ajp'在apache前面运行。另外值得注意的是，它使用的是表单身份验证，因此您输入的任何URL都应该将您重定向到登录页面。正如我所说的，这在所有浏览器中都能正常工作，但由于某种原因，重定向不能与Java 6中的URLConnection一起使用。

A bit more info on my servlet ... it is running in tomcat and fronted by apache using 'mod-proxy-ajp'. Also of note, it is using form authentication so any URL you enter should redirect you to the login page. As I said, this works correctly in all browsers, but for some reason the redirect isn't working with the URLConnection in Java 6.

感谢您阅读...的想法？

Thanks for reading ... ideas?

推荐答案

它显然是在无限循环中重定向，因为你没有维护用户会话。会话通常由cookie支持。在使用 URLConnection 之前，您需要创建一个 CookieManager 。

It's apparently redirecting in an infinite loop because you don't maintain the user session. The session is usually backed by a cookie. You need to create a CookieManager before you use URLConnection.

// First set the default cookie manager.
CookieHandler.setDefault(new CookieManager(null, CookiePolicy.ACCEPT_ALL));

// All the following subsequent URLConnections will use the same cookie manager.
URLConnection connection = new URL(url).openConnection();
// ...

connection = new URL(url).openConnection();
// ...

connection = new URL(url).openConnection();
// ...

参见：

• 使用java.net.URLConnection来触发和处理HTTP请求



See also:

• Using java.net.URLConnection to fire and handle HTTP requests

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