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>
标签：登录,request,用户,upwd,uname,jsp,import,login,页面 From： https://www.cnblogs.com/hmy22466/p/16794257.html