利用Java怎么编写一个DES加密解密工具类

package lsy;import java.security.Key;import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.KeyGenerator;import javax.crypto.SecretKey;import sun.misc.BASE64Decoder;import sun.misc.BASE64Encoder;public class DesUtil {  public static void main(String[] args) {  //以下是加密方法algorithm="AES"的测试  System.out.println(DesUtil.getInstance("lushuaiyin").getEnCodeString("hello"));  //输出 LDewGAZkmWHeYFjBz56ylw==  //将上面的密文解密：  System.out.println(DesUtil.getInstance("lushuaiyin").getDecodeString("LDewGAZkmWHeYFjBz56ylw=="));  //输出 hello  //改变密钥测试  System.out.println(DesUtil.getInstance("suolong").getEnCodeString("hello"));  //输出 /RLowOJ+Fr3KdMcdJeNatg==  System.out.println(DesUtil.getInstance("suolong").getDecodeString("/RLowOJ+Fr3KdMcdJeNatg=="));  //输出 hello  //如果使用不正确的密钥解密，将会：  System.out.println(DesUtil.getInstance("suolong").getDecodeString("LDewGAZkmWHeYFjBz56ylw==")); } private SecretKey key=null;//密钥 //定义 加密算法,可用 DES,DESede,Blowfish,AES //不同的加密方式结果会不同 private static String algorithm="AES"; private static DesUtil desUtil=null; public DesUtil(){} public static DesUtil getInstance(String strKey){  desUtil=new DesUtil();  desUtil.createKey(strKey);  return desUtil; }  public void createKey(String strKey){  try{   KeyGenerator kg=KeyGenerator.getInstance(DesUtil.algorithm);   byte[] bt=strKey.getBytes("UTF-8");   SecureRandom sr=new SecureRandom(bt);   kg.init(sr);   this.setKey(kg.generateKey());  }catch(Exception e){  } }  public String getEnCodeString(String dataStr){  byte[] miwen=null;//密文  byte[] mingwen=null;//明文  Cipher cipher;  String result="";//密文字符串  try{   mingwen=dataStr.getBytes("UTF-8");   cipher=Cipher.getInstance(DesUtil.algorithm);   cipher.init(Cipher.ENCRYPT_MODE, this.getKey());   miwen=cipher.doFinal(mingwen);   BASE64Encoder base64en = new BASE64Encoder();   result=base64en.encodeBuffer(miwen);//或者可以用下面的方法得到密文，结果是不一样的，都可以正常解密//   result=byte2hex(miwen);//密文结果类似2C:37:B0:18:06:64:99:61:DE:60:58:C1:CF:9E:B2:97  }catch(Exception e){   e.printStackTrace();  }  return result; }  public String getDecodeString(String codeStr){  BASE64Decoder base64De = new BASE64Decoder();  byte[] miwen=null;  byte[] mingwen=null;  String resultData="";//返回的明文  Cipher cipher;  try{   miwen=base64De.decodeBuffer(codeStr);   cipher=Cipher.getInstance(DesUtil.algorithm);   cipher.init(Cipher.DECRYPT_MODE, this.getKey());   mingwen=cipher.doFinal(miwen);   resultData = new String(mingwen,"UTF-8");  }catch(Exception e){   return "密钥不正确或其他原因导致异常，无法解密！";  }  return resultData; }  //二行制转字符串 public String byte2hex(byte[] b) {  String hs = "";  String stmp = "";  for (int n = 0; n < b.length; n++) {   stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));   if (stmp.length() == 1)    hs = hs + "0" + stmp;   else    hs = hs + stmp;   if (n < b.length - 1)    hs = hs + ":";  }  return hs.toUpperCase(); } public SecretKey getKey() {  return key; } public void setKey(SecretKey key) {  this.key = key; } public static String getAlgorithm() {  return algorithm; } public static void setAlgorithm(String algorithm) {  algorithm = algorithm; }}