java - 使用正则表达式模式验证域和子域的正则表达式是什么？

Question

我有一个域和子域列表，我正在检查该列表中的每个项目是否都是有效的域名（或子域），例如：www.google.com - google.com - drive.google.com。

这是我的正则表达式： ^((?!-)[A-Za-z0-9-]{1,63}(?<!-)\\.)+[A-Za-z]{2,6}$

这是我的代码：

// Validate Domains
    private boolean validateDomains (String domains) {
        String domainsList[] = domains.split("\\n");
        final Pattern domainPattern = Pattern.compile("^((?!-)[A-Za-z0-9-]{1,63}(?<!-)\\.)+[A-Za-z]{2,6}$");

        for (int i = 0; i < domainsList.length; i++) {
            if (!domainPattern.matcher(domainsList[i]).matches()) {
                return false;
            }
        }
        return true;
    }

此代码从未通过测试！

标签： javaregex

Answer 1

或者，您可能会为您的表达式添加更多边界，类似于：

(?i)^(?:https?:\/\/)?(?:www\.)?(?:[a-z0-9-]+\.){1,9}[a-z]{2,5}(?:\/.*)?$

演示 1

或者

(?i)^(?:https?:\/\/)?(?:www\.)?(?:[a-z0-9-]{1,20}\.){1,9}[a-z]{2,5}(?:\/.*)?$

演示 2

测试

import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class re{

    public static void main(String[] args){

        final String regex = "(?i)^(?:https?:\\/\\/)?(?:www\\.)?(?:[a-z0-9-]+\\.){1,9}[a-z]{2,5}(?:\\/.*)?$";
        final String string = "www.google.com\n"
             + "google.com\n"
             + "drive.google.com\n"
             + "http://www.google.com\n"
             + "http://google.com\n"
             + "http://drive.google.com\n"
             + "https://www.google.com\n"
             + "https://www.google.com\n"
             + "https://www.drive.google.com\n"
             + "https://www.google.com/some_other_things\n"
             + "https://www.google.com/\n"
             + "https://www.drive.google.com/\n"
             + "https://www.a.a.a.a.a.a.a.a.a.google.com/";

        final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
        final Matcher matcher = pattern.matcher(string);

        while (matcher.find()) {
            System.out.println("Full match: " + matcher.group(0));
            for (int i = 1; i <= matcher.groupCount(); i++) {
                System.out.println("Group " + i + ": " + matcher.group(i));
            }
        }

    }
}

输出

Full match: www.google.com
Full match: google.com
Full match: drive.google.com
Full match: http://www.google.com
Full match: http://google.com
Full match: http://drive.google.com
Full match: https://www.google.com
Full match: https://www.google.com
Full match: https://www.drive.google.com
Full match: https://www.google.com/some_other_things
Full match: https://www.google.com/
Full match: https://www.drive.google.com/

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如果您想简化/修改/探索表达式，它已在regex101.com的右上角面板中进行了说明。如果您愿意，您还可以在此链接中观看它如何与一些示例输入匹配。

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