function _acEncode(str){
    var s0, i, s, u;
    s0 = "";                
    for (i = 0; i < str.length; i++){  
        s = str.charAt(i);
        u = str.charCodeAt(i);          
        if (s == " "){s0 += "+";}    
        else {
            if ( u == 0x2a || u == 0x2d || u == 0x2e || u == 0x5f || ((u >= 0x30) && (u <= 0x39)) || ((u >= 0x41) && (u <= 0x5a)) || ((u >= 0x61) && (u <= 0x7a))){   
                s0 = s0 + s;            
            }
            else {                  
                if ((u >= 0x0) && (u <= 0x7f)){     
                    s = "0"+u.toString(16);
                    s0 += "%"+ s.substr(s.length-2);
                }
                else if (u > 0x1fffff){     
                    s0 += "%" + (oxf0 + ((u & 0x1c0000) >> 18)).toString(16);
                    s0 += "%" + (0x80 + ((u & 0x3f000) >> 12)).toString(16);
                    s0 += "%" + (0x80 + ((u & 0xfc0) >> 6)).toString(16);
                    s0 += "%" + (0x80 + (u & 0x3f)).toString(16);
                }
                else if (u > 0x7ff){        
                    s0 += "%" + (0xe0 + ((u & 0xf000) >> 12)).toString(16);
                    s0 += "%" + (0x80 + ((u & 0xfc0) >> 6)).toString(16);
                    s0 += "%" + (0x80 + (u & 0x3f)).toString(16);
                }
                else {                     
                    s0 += "%" + (0xc0 + ((u & 0x7c0) >> 6)).toString(16);
                    s0 += "%" + (0x80 + (u & 0x3f)).toString(16);
                }
            }
        }
    }
    return s0;
}