JSP---第十次作业

截图：

数据库信息：

输入正确：

当出现输入错误时：显示错误并返回登录页面

servlet配置：

建的类：

部分代码:

public class LoginServlet extends HttpServlet{
            //声明
         private final String SUCCESS_VIEW = "MyJsp.jsp";
         private final String ERROR_VIEW = "index.jsp";
         private  UsersDao userDao = new UsersDao();
         private BaseDao basedao = new BaseDao();
        
      
      protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doPost(request, response);
        }

        
    public void doPost(HttpServletRequest request,HttpServletResponse response)
            throws ServletException,IOException{
                //1.防止乱码
            request.setCharacterEncoding("utf-8");
            response.setContentType("text/html;charset=utf-8");
            //2.获取页面信息
             String username = request.getParameter("username");
            String password = request.getParameter("password");
            //3.获取登录用户信息
            request . getSession().setAttribute ( "UserName" , username ) ; 
            request.getSession().setAttribute("password", password);
            Connection con=null;
               //4.验证操作，将用户信息封装到currentUser
               try {
                   Users user = new Users(username,password);
                    con = basedao.getConnection();
                    Users currentUser = userDao.login(con, user);
                    if (null == currentUser) {
                        //5.输入信息错误
                        request.setAttribute("error", "用户名或密码错误");
                        request.setAttribute("userName", username);
                        request.setAttribute("password", password);
                        RequestDispatcher dispatcher = request.getRequestDispatcher(ERROR_VIEW);
                        dispatcher.forward(request, response);
                    }else {
                        //6.输入正确的信息
                        HttpSession session = request.getSession();
                        session.setAttribute("currentUser",currentUser);
                        response.sendRedirect(SUCCESS_VIEW );
                    }
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
         
    }
     
}

LoginServlet

 
  <body>
    <h1>登录</h1>
    <form action="textServlet" method="post">
        用户名：<input type="text" name="username" value="${username}" /><br/>
        密&nbsp;&nbsp; 码：<input type="password" name="password" value=""/><br/>
    <input type="submit" value="登录"/>
    <a href="regist.jsp">注册</a>
    </form>
    <font color="red">${error}</font>
  </body>

index.jsp(登录界面)

 <% 
    String userName = ( String ) session. getAttribute ( "UserName" ) ; 
   %> 
   <div align = center> 
   欢迎登陆！！
    当前用户：<%=userName%>

MyJsp.jsp(登录后显示界面)

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原文地址：https://www.cnblogs.com/XiaoPoHai-11/p/12967005.html