login.jsp：
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>User login</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> <span style="color: red;font-size: 12px"><%=request.getAttribute("msg")%></span>
</form>
</body>
</html>
index.jsp：
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<h2>Welcome<%=session.getAttribute("uname")%>login</h2>
</body>
</html>
LoginServlet.java
@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//Set the encoding format of the client (to prevent garbled characters)
req.setCharacterEncoding("UTF-8");
//Accept the parameters passed by the client
String uname = req.getParameter("uname");
String upwd = req.getParameter("upwd");
//Check if the parameter is empty
if (uname == null ||"".equals(uname.trim())) {
//Prompt user information
req.setAttribute("msg", "User name cannot be empty");
//Request forwarding jump to login.jsp
req.getRequestDispatcher("login.jsp").forward(req, resp);
return;
}
if (upwd == null||"".equals(upwd.trim())) {
//Prompt user information
req.setAttribute("msg", "User password cannot be empty");
//Request forwarding jump to login.jsp
req.getRequestDispatcher("login.jsp").forward(req, resp);
return;
}
// Determine if the account password is correct
if (!"admin".equals(uname)||!"admin".equals(upwd)) {
//Prompt user information
req.setAttribute("msg", "Login failed");
//Request forwarding jump to login.jsp
req.getRequestDispatcher("login.jsp").forward(req, resp);
return;
}
//login successful
//Set the login information to the session
req.getSession().setAttribute("uname",uname);
//Jump to index.jsp
resp.sendRedirect("index.jsp");
}
}