myeclipse生成序列号类

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;


public class Xulianhao {
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 type) {
NumberFormat nf = new DecimalFormat("000");
Calendar cal = Calendar.getInstance();
cal.add(Calendar.YEAR, 3);
cal.add(Calendar.DAY_OF_YEAR, -1);
String licenseNum = nf.format((int) (Math.random() * 1000));
String expTime = new StringBuilder("-").append(
new SimpleDateFormat("yyMMdd").format(cal.getTime())).append(
"0").toString();
String need = new StringBuilder(userId.substring(0, 1)).append("Y")
.append(type).append("-100").append(licenseNum).append(expTime)
.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 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();
if(userId == null || "".equals(userId)){
System.out.println("name is null");
System.exit(0);
}
Xulianhao myeclipsegen = new Xulianhao();
String res = myeclipsegen.getSerial(userId, "E3MS");
System.out.println("Serial:" + res);
reader.readLine();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}