java一级域名获取

import java.util.regex.Matcher;
import java.util.regex.Pattern;
private static String regex1="[0-9a-zA-Z]+((\\.com)|(\\.cn)|(\\.org)|(\\.net)|(\\.edu)|(\\.com.cn))";

Pattern p = Pattern.compile(regex1);  
Matcher m = p.matcher(url); 
List<String> strList = new ArrayList<String>();
    while(m.find()){
    strList.add(m.group());
}
String categoryId = strList.toString();
categoryId = categoryId.substring(1,categoryId.length()-1);