java实现MD5加密

 mport java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;  

 public class CreateMD5 {  

     //静态方法，便于作为工具类
     public static String getMd5(String plainText) {
         try {
             MessageDigest md = MessageDigest.getInstance("MD5");
             md.update(plainText.getBytes());
             byte b[] = md.digest();  

             int i;  

             StringBuffer buf = new StringBuffer("");
             for (int offset = 0; offset < b.length; offset++) {
                 i = b[offset];
                 if (i < 0)
                     i += 256;
                 if (i < 16)
                     buf.append("0");
                 buf.append(Integer.toHexString(i));
             }
             //32位加密
             return buf.toString();
             // 16位的加密
             //return buf.toString().substring(8, 24);
         } catch (NoSuchAlgorithmException e) {
             e.printStackTrace();
             return null;
         }  

     }  

     public static void main(String[] args) {
         //测试
         System.out.println(CreateMD5.getMd5("hello"));
     }  

 }