身份证的合法性验证/

    public  static  boolean checkidcard(String idcard)
    {
        String idcardnum=idcard.trim();
        int len=idcardnum.length();
        //身份证权重
        int weight[]= {7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2};
        char validate[]= {'1','0','X','9','8','7','6','5','4','3','2','x'};
        int sum=0;
        int mode=0;
        if(len==18||len==15)
        {
            if(len==18)
            {
                for(int i=0;i<len-1;i++)
                {
                    sum=sum+(idcardnum.charAt(i)-'0')*weight[i];
                }
                mode=sum%11;
                if(validate[mode]==idcardnum.charAt(17))
                {
                    return true;
                }
                else
                    return false;
            }    
        }
        else
        {
            return false;
        }
        return true;
    }