深入解析java中的locale

在项目中经常要用到将字符串解析成locale，但是没有一个比较好用的类。
java本身提供了3个构造函数，但是实际使用过程中，需要自己解析，比较繁琐。
locale(langugae)
locale(language,country)

locale(string language, string country, string variant)
apache 有个 localeutils.tolocale(string language)但是不支持最后2个字符为小写的，如:zh_cn支持， zh_cn就不支持。

参考其它方法，写了下面的类，做个笔记，也希望对解决类似问题的人有点帮助。

import java.util.locale;
public class localeutil
{
    private final static locale default_locale = locale.english;

    public final static string ietf_separator = "-"; 

    public final static string separator = "_"; 

    public final static string empty_string = "";

   
    public static locale tolocale( string language )
    {
        if( !stringutil.isnullorempty( language ) )
        {
            return langtolocale( language, separator );
        }
        return default_locale;
    }

     public static locale langtolocale( string lang , string separator )
     {
           if( stringutil.isnullorempty( lang ) )
           {
                return default_locale;
           }
            string language = empty_string;
            string country =  empty_string;
            string variant =  empty_string;
            int i1 = lang.indexof( separator );
            if ( i1 < 0 )
            {
                language = lang;
            } else
            {
                language = lang.substring(0, i1);
                ++i1;
                int i2 = lang.indexof( separator, i1);
                if (i2 < 0)
                {
                    country = lang.substring(i1);
                } else
                {
                    country = lang.substring(i1, i2);
                    variant = lang.substring(i2+1);
                }
            }

            if(language.length() == 2)
            {
               language = language.tolowercase();
            }else
            {
              language = empty_string;
            }

            if(country.length() == 2)
            {
               country = country.touppercase();
            }else
            {
              country = empty_string;
            }

            if( (variant.length() > 0) &&
                ((language.length() == 2) ||(country.length() == 2)) )
            {
               variant = variant.touppercase();
            }else
            {
                variant = empty_string;
            }

            return new locale(language, country, variant );
        }
}

注意：

 public class stringutil
{
    public static boolean isnullorempty(string target) {
        return target == null || "".equals(target);
    }
}