MyEclipse 6.5 注册码算法

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 (). 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;
  int j;
  int k;
  i = 0;
  ac = s.toCharArray();
  j = 0;
  k = ac.length;
  while (j < k) {
    i = (31 * i) + ac[j];
    j++;
  }
  return Math.abs(i);
}

private String change(String s) {
  byte[] abyte0;
  char[] ac;
  int i;
  int k;
  int j;
  abyte0 = s.getBytes();
  ac = new char[s.length()];
  i = 0;
  k = abyte0.length;
  while (i < k) {
    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;
    i++;
  }
  return String.valueOf(ac);
}

public MyEclipseGen() {
  super();
}

public static void main(String[] args) {
  try {
    System.out.println("please input register name:");
    BufferedReader reader = new BufferedReader(new InputStreamReader(
      System.in));
    String userId = null;
    userId = reader.readLine();
    MyEclipseGen myeclipsegen = new MyEclipseGen();
    String res = myeclipsegen.getSerial(userId, "5");
    System.out.println("Serial:" + res);
    reader.readLine();
  } catch (IOException ex) {
  }
}
}