myEclipse自动生成注册码

import java.io.BufferedReader;    
import java.io.IOException;    
import java.io.InputStreamReader;    
  
public class MyEclipseGen {    
private static final String LL = "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 String getSerial(String userId, String licenseNum) {    
  java.util.Calendar cal = java.util.Calendar.getInstance();    
  cal.add(1, 3);    
  cal.add(6, -1);    
  java.text.NumberFormat nf = new java.text.DecimalFormat("000");    
  licenseNum = nf.format(Integer.valueOf(licenseNum));    
  String verTime = new StringBuilder("-").append(    
    new java.text.SimpleDateFormat("yyMMdd").format(cal.getTime()))    
    .append("0").toString();    
  String type = "YE3MP-";    
  String need = new StringBuilder(userId.substring(0, 1)).append(type)    
    .append("300").append(licenseNum).append(verTime).toString();    
  String dx = new StringBuilder(need).append(LL).append(userId)    
    .toString();    
  int suf = this.decode(dx);    
  String code = new StringBuilder(need).append(String.valueOf(suf))    
    .toString();    
  return this.change(code);    
}    
  
private int decode(String s) {    
  int i;    
  char[] ac;