Java で URL 情報からドメインやらを抽出してみたかったので，Guava の InternetDomainName を使ってみた．

InternetDomainName (Guava: Google Core Libraries for Java 19.0-SNAPSHOT API)

サンプルコード

package com.kakakakakku.guava;

import com.google.common.net.InternetDomainName;
import java.net.URL;

public class UrlParser {
    public static void main(String[] args) throws Exception {
        URL url = new URL("http://kakakakakku.hatenablog.com/");
        System.out.println(url.getHost());
        System.out.println(InternetDomainName.from(url.getHost()).topPrivateDomain());
        System.out.println(InternetDomainName.from(url.getHost()).publicSuffix());
    }
}

実行結果

kakakakakku.hatenablog.com
hatenablog.com
com