Myeclipse 5.1 注册码算法

import java.io.*;  

public class Main 
{
private static final String L = "Decompiling this copyrighted software is a violation of both your license agreement and the Digital Millenium Copyright Act of 1998 (http://www.loc.gov/copyright/legislation/dmca.pdf). Under section 1204 of the DMCA, penalties range up to a $500,000 fine or up to five years imprisonment for a first offense. Think about it; pay for a license, avoid prosecution, and feel better about yourself.";
public static void main(String[] args) {
String userId = "xiangfei";
//MyEclipse4.1 GA 其中491(4.9.1)/400(4.0)/401(4.1)/501(5.1.0)，()内为版本号，9912310代表注册码过期时间2099/12/31
String need = userId.substring(0,1) + "YE3MP-401-00-9912310";
//MyEclipse4.0.0 GA
//String need = userId.substring(0,1) + "YE3MP-400-01-9912310";
//MyEclipse4.9.1
//String need = userId.substring(0,1) + "YE3MP-491-01-9912310";
//MyEclipse5.1.0 GA
//String need = userId.substring(0,1) + "YE3MP-501-00-9912310";
String dx = need + L + userId;
int suf = decode(dx);
//System.out.println("SUF:"+suf);
String code = need + suf;
System.out.println(change(code));
}
static int decode(String s) {
int i = 0;
char ac[] = s.toCharArray();
int j = 0;
for(int k = ac.length; j < k; j++) {
i = 31 * i + ac[j];
}
return Math.abs(i);
}
static String change(String s) {
byte abyte0[] = s.getBytes();
char ac[] = new char[s.length()];
int i = 0;
for(int k = abyte0.length; i < k; i++) {
int j = abyte0[i];
if(j >= 48 && j <= 57)
j = ((j - 48) + 5) % 10 + 48;
else
if(j >= 65 && j <= 90)
j = ((j - 65) + 13) % 26 + 65;
else
if(j >= 97 && j <= 122)
j = ((j - 97) + 13) % 26 + 97;
ac[i] = (char)j;
}
return String.valueOf(ac);
}
}