myeclipseレジストリコードの生成

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;
	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) {
	}
    }
}