Java实现md5和base64加密解密操作

import java.io.IOException;
import java.security.MessageDigest;

import sun.misc.BASE64Encoder;
import sun.misc.BASE64Decoder;


public class MD5Util {
  /**
   * MD5加密
   */
   public static String md5Encryption(String str) {
     MessageDigest md5 = null;  
     try {  
      md5 = MessageDigest.getInstance("MD5");  
     } catch (Exception e) {  
      System.out.println(e.toString());  
      e.printStackTrace();  
      return "";  
     }  
     char[] charArray = str.toCharArray();  
     byte[] byteArray = new byte[charArray.length];  
     
     for (int i = 0; i < charArray.length; i++)  
      byteArray[i] = (byte) charArray[i];  
     
     byte[] md5Bytes = md5.digest(byteArray);  
     
     StringBuffer hexValue = new StringBuffer();  
     
     for (int i = 0; i < md5Bytes.length; i++) {  
      int val = ((int) md5Bytes[i]) & 0xff;  
      if (val < 16)  
      hexValue.append("0");  
      hexValue.append(Integer.toHexString(val));  
     }  
     
     return hexValue.toString(); 
  }
   
   /**
   * base64加密
   */
   public static String base64Encryption(String str) {
    if (str == null) return null; 
    String encodeStr = "";
    
    try {
      BASE64Encoder b64Encoder = new BASE64Encoder();
      encodeStr = b64Encoder.encode(str.getBytes());
    } catch (Exception e) {
      e.printStackTrace();
    }
    
    
    return encodeStr;
  }
   /**
   * base64解密
   */
   public static String base64Dcrypt(String str) {
    if (str == null) return null; 
    String decoderStr = "";
    
    try {
      BASE64Decoder decoder = new BASE64Decoder();
      byte[] b = decoder.decodeBuffer(str);
      decoderStr = new String(b);
    } catch (IOException e) {
      e.printStackTrace();
      return null; 
    }
    
    return decoderStr;
  }
}