java类自动生成Eclipse注册码

package com;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
* 这是一个来自网上的一个MyEclipse的java版的注册机。
* 收藏：赵永恩
* 示例结果：
*
* please input register name: admin_yong
* Serial:nLR8ZC-855575-68655456975372753
*
*/
public class Register_Eclipse {
    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 Register_Eclipse() {
        super();
    }

    public static void main(String[] args) {
        try {
            // 输入注册名
            System.out.println("please input register name:");
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    System.in));
            String userId = null;
            userId = reader.readLine();
            Register_Eclipse myeclipsegen = new Register_Eclipse();
            String res = myeclipsegen.getSerial(userId, "20");
            // 注册号
            System.out.println("Serial:" + res);
            reader.readLine();
        } catch (IOException ex) {
        }
    }

}