java獲取URL中的頂級域名domain

此類提供了獲取url的頂級域名和判斷兩個url的頂級域名是否相等，可直接使用。

import java.net.MalformedURLException;
import java.net.URL;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.regex.Pattern;

public class URLUtil {

	private final static Set<String> PublicSuffixSet = new HashSet<String>(
			Arrays.asList(new String(
					"com|org|net|gov|edu|co|tv|mobi|info|asia|xxx|onion|cn|com.cn|edu.cn|gov.cn|net.cn|org.cn|jp|kr|tw|com.hk|hk|com.hk|org.hk|se|com.se|org.se")
					.split("\\|")));

	private static Pattern IP_PATTERN = Pattern
			.compile("(\\d{1,3}\\.){3}(\\d{1,3})");

	/**
	 * 獲取url的頂級域名
	 * @param url
	 * @return
	 */
	public static String getDomainName(URL url) {
		String host = url.getHost();
		if (host.endsWith("."))
			host = host.substring(0, host.length() - 1);
		if (IP_PATTERN.matcher(host).matches())
			return host;

		int index = 0;
		String candidate = host;
		for (; index >= 0;) {
			index = candidate.indexOf('.');
			String subCandidate = candidate.substring(index + 1);
			if (PublicSuffixSet.contains(subCandidate)) {
				return candidate;
			}
			candidate = subCandidate;
		}
		return candidate;
	}

	/**
	 * 獲取url的頂級域名
	 * @param url
	 * @return
	 * @throws MalformedURLException
	 */
	public static String getDomainName(String url) throws MalformedURLException {
		return getDomainName(new URL(url));
	}

	/**
	 * 判斷兩個url頂級域名是否相等
	 * @param url1
	 * @param url2
	 * @return
	 */
	public static boolean isSameDomainName(URL url1, URL url2) {
		return getDomainName(url1).equalsIgnoreCase(getDomainName(url2));
	}

	/**
	 * 判斷兩個url頂級域名是否相等
	 * @param url1
	 * @param url2
	 * @return
	 * @throws MalformedURLException
	 */
	public static boolean isSameDomainName(String url1, String url2)
			throws MalformedURLException {
		return isSameDomainName(new URL(url1), new URL(url2));
	}

}