well I have a jsp page with a login form, i'm using a servlet, if the username and password are correct the servlet redirects the user to another page else it redirects him to the login page again
when i log in with a correct username and password i'm redirected perfectly to reservation.jsp but when i put a wrong username or password in the form when i click on the submit button the page became blank
here is the servlet
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;
import javax.servlet.RequestDispatcher;
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 javax.servlet.http.HttpSession;
import com.mysql.jdbc.PreparedStatement;
/**
* Servlet implementation class LogServlet
*/
@WebServlet("/LogServlet")
public class LogServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public LogServlet() {
super();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("text/html");
String name=request.getParameter("name");
String password=request.getParameter("password");
PreparedStatement ps = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/log",
"root","");
ps = (PreparedStatement) conn.prepareStatement("select nom_client,username,password from client where username = ? and password = ?");
ps.setString(1, name);
ps.setString(2, password);
rs=ps.executeQuery();
try {
while(rs.next()){
if(password.equals(rs.getString("password")) && name.equals(rs.getString("username"))){
HttpSession session=request.getSession();
session.setAttribute("name",name);
PrintWriter out=response.getWriter();
request.getRequestDispatcher("reservation.jsp").include(request, response);
}
else{
response.sendRedirect("/login.jsp");
}}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.close();
}
catch(Exception e){e.printStackTrace();}
}
}
use request.getContextPath()
, It will redirect you to login page.
response.sendRedirect(request.getContextPath()+"/login.jsp");
and if you are reaching to your login page in that case, pass request
and response
objects to your jsp page.
request.getRequestDispatcher(request.getContextPath()+"/login.jsp").forward(request,response);
use this.
request.getRequestDispatcher("/login.jsp").forward(request,response);
As you have used
request.getRequestDispatcher("reservation.jsp").include(request, response);
to forward after successful login and as it is working, why not forwarding after failed also in this way .?
Which mean to use
request.getRequestDispatcher("/login.jsp").include(request, response);
request.getRequestDispatcher("login.jsp").include(request, response);
Have u tried above code in else part ? I think it should work
Problem is response.sendRedirect(...)
does not prepend the context path where the resource (jsp) is bundled. Try using request.getRequestDispatcher(...)
in both cases.
The problem could be here:
response.sendRedirect("/login.jsp");
This means that in the location header of the redirect response you will have:
http://localhost:8080/login.jsp
If you change it to:
response.sendRedirect("login.jsp");
than its relative to your webabb context path:
http://localhost:8080/app/login.jsp
Try with firebug or similar and trace down request/response you should find out quickly. And be sure jsp files are were expected in the hierarchy.
Hope this helps
Rather than giving response.sendRedirect("\\login.jsp"); use response.sendRedirect("/yourprojectname/"); and in welcome file in web.xml set login.jsp as welcome file.
Add this
response.sendRedirect("/yourprojectname/");
and set login.jsp as welcome file in web.xml
来自数据库的响应为空,因此我不得不将该案例添加到类中(通过if/else
条件)。
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