从 URL 字符串中提取主机名/域名 [英] Extract host name/domain name from URL string

问题描述

我有一个类似 http://hostname:port_no/control/login.jsp 的 URL.

I have a URL like http://hostname:port_no/control/login.jsp.

我将上述 url 存储在某个字符串中.现在，我需要从字符串中提取 hostname.

I have the above url stored in some String.Now, I need to extract hostname from the String.

我在我的 Java 代码中这样做

I am doing like this in my Java code

String domain = url.substring(url.indexOf('/') + 2, url.lastIndexOf(':'));

我想知道是否有更好的方法来做同样的事情.

I want to know if there is any better way to do the same.

推荐答案

您可以使用 java.net.URI-class 从字符串中提取主机名.

You can use the java.net.URI-class to extract the hostname from the string.

下面是一种可以从字符串中提取主机名的方法.

Here below is a method from which you can extract your hostname from a string.

public String getHostName(String url) {
    URI uri = new URI(url);
    String hostname = uri.getHost();
    // to provide faultproof result, check if not null then return only hostname, without www.
    if (hostname != null) {
        return hostname.startsWith("www.") ? hostname.substring(4) : hostname;
    }
    return hostname;
}

以上为您提供了主机名，如果您的主机名确实以 hostname.com/... 或 www.hostname.com/... 开头，则它是万无一失的>，它将返回主机名".

This above gives you the hostname, and is faultproof if your hostname does start with either hostname.com/... or www.hostname.com/..., which will return with 'hostname'.

如果给定的 url 无效(未定义的主机名)，则返回 null.

If the given url is invalid (undefined hostname), it returns with null.

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