从网址获取域/主​​机名的最快方式是什么？ [英] What is the fastest way to get the domain/host name from a URL?

问题描述

我需要查看大量的字符串url，并从中提取域名。

I need to go through a large list of string url's and extract the domain name from them.

例如：

http://www.stackoverflow.com/questions 将提取 www.stackoverflow.com

我最初是使用新的URL（theUrlString）.getHost（），但URL对象初始化为进程添加了很多时间，似乎不需要。

I originally was using new URL(theUrlString).getHost() but the URL object initialization adds a lot of time to the process and seems unneeded.

是否有更快的方法来提取可靠的主机名？

Is there a faster method to extract the host name that would be as reliable?

谢谢

编辑：我的错误，是的www。将包含在上面的域名示例中。此外，这些网址可能是http或https

My mistake, yes the www. would be included in domain name example above. Also, these urls may be http or https

推荐答案

如果您要处理 https etc，我建议你这样做：

If you want to handle https etc, I suggest you do something like this:

int slashslash = url.indexOf("//") + 2;
domain = url.substring(slashslash, url.indexOf('/', slashslash));

请注意，这包括 www （就像 URL.getHost（）会做），这实际上是域名的一部分。

Note that this is includes the www part (just as URL.getHost() would do) which is actually part of the domain name.

编辑通过评论请求

这里有两种可能有帮助的方法：

Here are two methods that might be helpful:

/**
 * Will take a url such as http://www.stackoverflow.com and return www.stackoverflow.com
 * 
 * @param url
 * @return
 */
public static String getHost(String url){
    if(url == null || url.length() == 0)
        return "";

    int doubleslash = url.indexOf("//");
    if(doubleslash == -1)
        doubleslash = 0;
    else
        doubleslash += 2;

    int end = url.indexOf('/', doubleslash);
    end = end >= 0 ? end : url.length();

    int port = url.indexOf(':', doubleslash);
    end = (port > 0 && port < end) ? port : end;

    return url.substring(doubleslash, end);
}


/**  Based on : http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/2.3.3_r1/android/webkit/CookieManager.java#CookieManager.getBaseDomain%28java.lang.String%29
 * Get the base domain for a given host or url. E.g. mail.google.com will return google.com
 * @param host 
 * @return 
 */
public static String getBaseDomain(String url) {
    String host = getHost(url);

    int startIndex = 0;
    int nextIndex = host.indexOf('.');
    int lastIndex = host.lastIndexOf('.');
    while (nextIndex < lastIndex) {
        startIndex = nextIndex + 1;
        nextIndex = host.indexOf('.', startIndex);
    }
    if (startIndex > 0) {
        return host.substring(startIndex);
    } else {
        return host;
    }
}

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