HttpUrlConnection 获取内容标题并获得“永久移动”

Question

这是我用 Groovy 编写的代码，用于从 URL 中获取页面标题。然而，有些网站我得到了“永久移动”，我认为这是因为 301 重定向。我如何避免这种情况并让 HttpUrlConnection 跟随正确的 URL 并获得正确的页面标题

例如这个网站我得到了“永久移动”而不是正确的页面标题 http ://www.nytimes.com/2011/08/14/arts/music/jay-z-and-kanye-wests-watch-the-throne.html

        def con = (HttpURLConnection) new URL(url).openConnection()
        con.connect()

        def inputStream = con.inputStream

        HtmlCleaner cleaner = new HtmlCleaner()
        CleanerProperties props = cleaner.getProperties()

        TagNode node = cleaner.clean(inputStream)
        TagNode titleNode = node.findElementByName("title", true);

        def title = titleNode.getText().toString()
        title = StringEscapeUtils.unescapeHtml(title).trim()
        title = title.replace("\n", "");
        return title

Answer 1

如果我自己管理重定向，我就可以让它工作...

我认为问题是该网站会期望它在重定向链的一半位置发送cookie，如果它没有收到它们，它会将您发送到登录页面。

这段代码显然需要一些清理（并且可能有更好的方法来做到这一点），但它显示了我如何提取标题：

@Grab( 'net.sourceforge.htmlcleaner:htmlcleaner:2.2' )
@Grab( 'commons-lang:commons-lang:2.6' )
import org.apache.commons.lang.StringEscapeUtils
import org.htmlcleaner.*

String location = 'http://www.nytimes.com/2011/08/14/arts/music/jay-z-and-kanye-wests-watch-the-throne.html'
String cookie = null
String pageContent = ''

while( location ) {
  new URL( location ).openConnection().with { con ->
    // We'll do redirects ourselves
    con.instanceFollowRedirects = false

    // If we got a cookie last time round, then add it to our request
    if( cookie ) con.setRequestProperty( 'Cookie', cookie )
    con.connect()

    // Get the response code, and the location to jump to (in case of a redirect)
    int responseCode = con.responseCode
    location = con.getHeaderField( "Location" )

    // Try and get a cookie the site will set, we will pass this next time round
    cookie = con.getHeaderField( "Set-Cookie" )

    // Read the HTML and close the inputstream
    pageContent = con.inputStream.withReader { it.text }
  }
}

// Then, clean paceContent and get the title
HtmlCleaner cleaner = new HtmlCleaner()
CleanerProperties props = cleaner.getProperties()

TagNode node = cleaner.clean( pageContent )
TagNode titleNode = node.findElementByName("title", true);

def title = titleNode.text.toString()
title = StringEscapeUtils.unescapeHtml( title ).trim()
title = title.replace( "\n", "" )

println title

希望它有帮助！

Answer 2

您需要在 HttpUrlConnection 上调用 setInstanceFollowRedirects(true)。即在第一行之后插入
con.setInstanceFollowRedirects(true)