HttpURLConnection -枚举所有302个重定向跳

Question

我的目标是使用java.net.HttpURLConnection来解析给定URL的所有302个重定向跳。

这是我的代码片段(实际上我在Talend SW中使用它)：

String url = row2.url;
java.net.HttpURLConnection con = (java.net.HttpURLConnection) new java.net.URL(url).openConnection();
con.setInstanceFollowRedirects(false);
con.connect();
String realURL = con.getHeaderField("Location");

System.out.println(realURL);

如果只有一个302的回复，它就会运行得很好。例如，如果我填充row2.ulr= "https://jigsaw.w3.org/HTTP/300/302.html“，代码将输出-> https://jigsaw.w3.org/HTTP/300/Overview.html，它是100%正确的。

我的问题是我无法解析几个302个回复，一个典型的例子是Facebook : www.facebook.com/ID_account >redirect-> www.facebook.com/ACCOUNT_NAME

使用在线重定向检查器，我找到了2-302个响应(我需要第二个响应)：

​

这是卷曲输出：

> >>> http://www.facebook.com/123456789
> 
> > --------------------------------------------
> > 302 Found
> > --------------------------------------------
> 
> Status:   302 Found Code: 302
> Location: https://www.facebook.com/123456789 Vary:    Accept-Encoding
> Content-Type: text/html; charset=UTF-8
> X-FB-Debug:   Muf4PfCP9TRKCO17QUf7SV2vsdnrCu6Gw2+sjWAKe0QPGdAToJPcmgH5LHv3NIAhzsJXfPB3a9/mVtuhiiEihA==
> Date: Mon, 16 Oct 2017 16:02:55 GMT Connection:   close
> Content-Length:   0
> 
> 
> 
> 
> >>> https://www.facebook.com/123456789
> 
> > --------------------------------------------
> > 302 Found
> > --------------------------------------------
> 
> Status:   302 Found Code: 302 X-XSS-Protection:   0
> public-key-pins-report-only:  max-age=600;
> pin-sha256="WoiWRyIOVNa9ihaBciRSC7XHjliYS9VwUGOIud4PB18=";
> pin-sha256="k2v657xBsOVe1PQRwOsHsw3bsGT2VzIqz5K+59sNQws=";
> pin-sha256="gMxWOrX4PMQesK9qFNbYBxjBfjUvlkn/vN1n+L9lE5E=";
> pin-sha256="q4PO2G2cbkZhZ82+JgmRUyGMoAeozA+BSXVXQWB8XWQ=";
> report-uri="http://reports.fb.com/hpkp/" Pragma:  no-cache
> Location: https://www.facebook.com/a_name_account/
> Cache-Control:    private, no-cache, no-store, must-revalidate
> X-Frame-Options:  DENY Strict-Transport-Security: max-age=15552000;
> preload X-Content-Type-Options:   nosniff Expires:    Sat, 01 Jan 2000
> 00:00:00 GMT Vary:    Accept-Encoding Content-Type:   text/html;
> charset=UTF-8
> X-FB-Debug:   j2KCBNZ1poIJ0xUeeQYbinpcqq2avoI4z8eWb9Dx/yUUg98uyGYGadydia7en1s5X4DJeaJB7VjxYaRvP+psCw==
> Date: Mon, 16 Oct 2017 16:02:55 GMT Connection:   close
> Content-Length:   0
> 
> 
> 
> 
> >>> https://www.facebook.com/a_name_account/

关于如何找到第二个302号“位置”的任何建议，->帐户/

谢谢你，雷格斯S。

Answer 1

对于递推法来说，这将是很好的行为。

如果确定响应头中仍有位置，则可以继续调用方法。

public void recurseLocation(String url) {

    URL url = new URL(location);
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
    connection.setInstanceFollowRedirects(false);
    connection.connect();
    String newLocation = connection.getHeaderField("Location");

    if (newLocation != null) {
        newLocation = recurseLocation(newLocation);
    } else {
        newLocation = location;
    }

    return newLocation;
}