//javascript客户端规定最多输入的字符串长度
function CheckLen(obj,maxlen) 
{
    var str="";
    str = obj.value;
    str = str.replace(/[^\x00-\xff]/g,"**"); 

    if (str.length > maxlen)
    {
        obj.value = GetLenStr(obj.value, maxlen);
    }
}

function GetLenStr(val, num)
{
    var ch,bytenum=0;
    var rs = "";
    var pt = /[^\x00-\xff]/;
    for (var i=0; i < num; i++)
    {
        ch = val.substr(i, 1);
        if (ch.match(pt))
        {
            bytenum += 2;
            if (bytenum > num)
            {
                return rs;
            }
        }
        else
        {
            bytenum += 1;
        }
        rs += ch;
        if (bytenum == num)
        {
            return rs;
        }
    }
    return rs;
}