登录注册功能使用md5对密码进行加密

电玩女神 2022-01-30 13:59 288阅读 0赞

之前一直搞不清楚md5加密，从网上查了好多资料、看了几个视频都没实现成功。这一次参加学校的集中实习，培训老师带我们简单实现了一下。

要简单实现并不难，先从网上down一个简单的md5算法：

1.      package com.train.util;
        import java.math.BigInteger;
        import java.security.MessageDigest;
        import java.security.NoSuchAlgorithmException;
         
        public class MD5Utils {
        	/**
        	 * 使用md5的算法进行加密
        	 */
        	public static String md5(String plainText) {
        		byte[] secretBytes = null;
        		try {
        			secretBytes = MessageDigest.getInstance("md5").digest(
        					plainText.getBytes());
        		} catch (NoSuchAlgorithmException e) {
        			throw new RuntimeException("没有md5这个算法！");
        		}
        		String md5code = new BigInteger(1, secretBytes).toString(16);// // 16进制数字
        		// 如果生成数字未满32位，需要前面补0
        		for (int i = 0; i < 32 - md5code.length(); i++) {
        			md5code = "0" + md5code;
        		}
        		return md5code;
        	}
        ｝
    
    然后在 Servlet或者控制器里直接调用MD5的这个静态方法就可以了：
2.      protected void doPost(HttpServletRequest request, HttpServletResponse response)
        			throws ServletException, IOException {
         
        		request.setCharacterEncoding("utf-8");
        		String userName = request.getParameter("userName");
        		String passWord = MD5Utils.md5(request.getParameter("passWord"));
        		userModel model = new userModel();
        		model.setUserName(userName);
        		model.setPassWord(passWord);
        		userService service = new userService();
        		try {
        			userModel m = service.selectByName(model.getUserName());
        			if (m == null) { // 如果找不到同名的记录，则可以注册
        				int i = service.save(model);
        				if (i > 0) {
        					request.setAttribute("msg", "注册成功！请登录！");
        					request.getRequestDispatcher("login.jsp").forward(request, response);
        				} else {
        					request.setAttribute("msg", "注册失败！请重新注册！");
        					request.getRequestDispatcher("index.jsp").forward(request, response);
        				}
        			} else {
        				request.setAttribute("msg", "用户名重复！请重新注册！");
        				request.getRequestDispatcher("index.jsp").forward(request, response);
        			}
        		} catch (Exception e) {
        			e.printStackTrace();
        		}
         
        	}
    
    这样注册进去的就是经过md5加密后的密文了。
    
    然后登录功能要比对密码的时候，从数据库中取出的是密文，需要将用户输入的密码再进行md5加密以后再比对，否则就会失败：
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response)
        			throws ServletException, IOException {
         
        		request.setCharacterEncoding("utf-8");
        		String userName = request.getParameter("userName");
        		String passWord = MD5Utils.md5(request.getParameter("passWord"));
        		userModel model = new userModel();
        		model.setUserName(userName);
        		model.setPassWord(passWord);
         
        		userService service = new userService();
         
        		if (request.getSession().getAttribute("checkcode_session").equals(request.getParameter("checkCode"))) {
         
        			try {
        				userModel md = service.selectByNameAndPass(model);
        				if (md != null) {
        					// 找到记录，登录成功
        					request.getSession().setAttribute("userName", md.getUserName());
        					request.getRequestDispatcher("welcome.jsp").forward(request, response);
        				} else {
        					request.setAttribute("msg", "登录失败！请重试！");
        					request.getRequestDispatcher("login.jsp").forward(request, response);
        				}
        			} catch (Exception e) {
        				e.printStackTrace();
        			}
        		} else {
        			request.setAttribute("msg", "验证码输入有误！请重试！");
        			request.getRequestDispatcher("login.jsp").forward(request, response);
        		}
         
        	}