java MD5 密码加密例子

public String md5Digest(String src) throws Exception {           // 定义数字签名方法, 可用：MD5, SHA-1           MessageDigest md = MessageDigest.getInstance("MD5");           byte[] b = md.digest(src.getBytes("utf-8"));                        return this.byte2HexStr(b);      }         private String byte2HexStr(byte[] b) {           StringBuilder sb = new StringBuilder();           for (int i = 0; i < b.length; i++) {               String s = Integer.toHexString(b[i] & 0xFF);               if (s.length() == 1) {                    sb.append("0");               }                                  sb.append(s.toUpperCase());            }                           return sb.toString();       }