MyEclipse 秘钥生成器

import java.io.*;     
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.servlet.http.HttpServletRequest;


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) throws ParseException {      
        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, "20");      
            System.out.println("Serial:" + res);      
            reader.readLine();      
        } catch (IOException ex) {      
        }      
    }      
}