简单用户登录页面

login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登录</title>
</head>
<body>
    <form action="loginServlet" method="post">
    姓名：<input type="text" name="uname"><br>
    密码：<input type="password" name="upwd"><br>
        <button>登录</button>
<%-- 获取后台设置在作用域中的数据，并显示  --%>
<%--        <span style="color: red;font-size: 12px"><%=request.getAttribute("msg")%></span>--%>
<%--        选择使用EL表达式上面那个表达式会出现默认的null       --%>
        <span style="color: red;font-size: 12px">${msg}</span>
    </form>
</body>
</html>

loginServlet.java

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/loginServlet")
public class loginServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置编译格式
        request.setCharacterEncoding("UTF-8");
        //接收参数
        String uname=request.getParameter("uname");
        String upwd=request.getParameter("upwd");
        //判断参数是否为空
        if(uname==null|| "".equals(uname.trim())){
            //提示用户信息不能为空
            request.setAttribute("msg","用户姓名不能为空");
            //请求转发，跳转到login.jsp页面
            request.getRequestDispatcher("login.jsp").forward(request,response);
            return;
        }
        if(upwd==null|| "".equals(upwd.trim())){
            //提示用户信息不能为空
            request.setAttribute("msg","用户密码不能为空");
            //请求转发，跳转到login.jsp页面
            request.getRequestDispatcher("login.jsp").forward(request,response);
            return;
        }
        //账号密码是否正确  假如是uname=hmy upwd=123456
        if(!"hmy".equals(uname)||!"123456".equals(upwd)){
            request.setAttribute("msg","登录失败");
            //请求转发，跳转到login.jsp页面
            request.getRequestDispatcher("login.jsp").forward(request,response);
            return;
        }
        //登录成功：跳转到首页
        request.getSession().setAttribute("uname",uname);
        response.sendRedirect("index.jsp");

    }
}

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
    <h2>欢迎<%=session.getAttribute("uname")%>登录</h2>
  </body>
</html>

posted on 2022-10-15 15:11 201812 阅读(42) 评论(0) 编辑收藏举报