common_helper/src/main/java/com/xiongyingqi/util/MD5Crypt.java
static private final String to64(long v, int size) {
        StringBuffer result = new StringBuffer();

        while (--size >= 0) {
            result.append(itoa64.charAt((int) (v & 0x3f)));
            v >>>= 6;
        }

        return result.toString();
    }
static private final String to64(long v, int size) {
        StringBuffer result = new StringBuffer();

        while (--size >= 0) {
            result.append(itoa64.charAt((int) (v & 0x3f)));
            v >>>= 6;
        }

        return result.toString();
    }
static private final String to64 ( long v , int size ) { StringBuffer result = new StringBuffer ( ) ; while ( -- size >= 0 ) { result . append ( itoa64 . charAt ( ( int ) ( v & 0x3f ) ) ) ; v >>>= 6 ; } return result . toString ( ) ; }
Function to return a string from the set: A-Za-z0-9./

@param size Length of the string
@param v    value to be converted
@return A string of size (size) from the set A-Za-z0-9./
Function to return a string from the set : A - Za - z0 - 9 . /