哈希密码确认错误

Question

我正在使用Java Eclipse并将密码散列到MySQL数据库中。创建新用户时，我将密码哈希，然后将其存储到数据库中。当用户登录时，我将密码哈希，然后将其与数据库上的密码进行比较。但是，我在两个地方打印哈希密码，虽然我在两个实例中输入相同的原始密码，但哈希值不同。这是我的哈希函数：

// hash the password to store in database
            String hashed_password = passwordField.toString();
            MessageDigest md = null;
            try {
                md = MessageDigest.getInstance("MD5");
            } catch (NoSuchAlgorithmException e2) {
                // TODO Auto-generated catch block
                e2.printStackTrace();
            }
            md.update(hashed_password.getBytes());

            byte byteData[] = md.digest();

            //convert the byte to hex format method 1
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < byteData.length; i++) {
             sb.append(Integer.toString((byteData[i] & 0xff) + 0x100, 16).substring(1));
            }

            System.out.println("Digest(in hex format):: " + sb.toString());
            // end of hashing

这是我的比较：

String query = "select * from user where username=? and password=?";
                    PreparedStatement pst = connection.prepareStatement(query);
                    pst.setString(1, userNameTextField.getText() );
                    //pst.setString(2 , passwordField.getText() );
                    pst.setString(2 , sb.toString() );

                    username = userNameTextField.getText();

                    ResultSet rs = pst.executeQuery();
                    int count = 0;
                    while(rs.next()){
                        count++;

                    }
                    if(count == 1){
                        //JOptionPane.showMessageDialog(null, "Username and password is correct");
                        listener.userLoggedIn(new UserAccount());