自动成成myEclipse注册码的类

import java.io.*;

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