servlet

print("code sample");
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*; 
import java.sql.*;
public class Login extends HttpServlet
{
  public void doGet(HttpServletRequest req, HttpServletResponse res)throws ServletException, IOException
  { 
   PrintWriter pw=res.getWriter();
   res.setContentType("text/html");
   pw.println("Hello"); 
    try 
       {
        Class.forName("com.mysql.jdbc.Driver");
        Connection con=DriverManager.getConnection("jdbc:mysql://localhost/latha","root","root");
      String uid=req.getParameter("Userid"); 
        String un=req.getParameter("Username"); 
        String p=req.getParameter("Password"); 

 PreparedStatement p1=con.prepareStatement("select * from Logintab where Userid=? and Username=? and  Password=?");
    p1.setString(1,uid);
    p1.setString(2,un);
    p1.setString(3,p);
    ResultSet r=p1.executeQuery();
   boolean b=r.next();


  if(b=true)

{
res.sendRedirect("http://localhost:8080/lata/Pms.html");

}

 else
  {

    pw.println("login is not successful");

      }

   con.close();
    }
      catch (Exception e)
      {
        pw.println(e);
      }
    }

}

this is the code for .java servlet am able to run sucessful but when i give wrong login it won't display login is not sucessful .instead it redirect to pms.html

View Answers

January 7, 2011 at 5:10 PM

Hello Friend,

The sendRedirect()method redirects the page so your message is not getting displayed. IF you want this, then try the following code:

1)login.jsp:

<html>
<script>
function validate(){
var username=document.form.user.value;
var password=document.form.pass.value;
if(username==""){
 alert("Enter Username!");
  return false;
}
if(password==""){
 alert("Enter Password!");
  return false;
}
return true;
}
</script>
<form name="form" method="post" action="../Login" onsubmit="javascript:return validate();">
<table>
<tr><td>Username:</td><td><input type="text" name="user"><label id="lab1"></label></td></tr>
<tr><td>Password:</td><td><input type="password" name="pass"><label id="lab2"></label></td></tr>
<tr><td></td><td><input type="submit" value="Submit"></td></tr>
</table>
</form>
</html>
<%String msg=request.getParameter("msg");
if(msg!=null){
    %>
<label><font color="red"><%=msg%></font></label> 
<%
}
    %>

2)Login.java:

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class Login extends HttpServlet{

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    try{
        response.setContentType("text/html");
        PrintWriter out=response.getWriter();
       String user=request.getParameter("user");
       String pass=request.getParameter("pass");
           Class.forName("com.mysql.jdbc.Driver");
           Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root");
           Statement st=con.createStatement();
           ResultSet rs=st.executeQuery("select * from login where username='"+user+"' and password='"+pass+"'");
           int count=0;
           while(rs.next()){
           count++;
           }
           if(count>0){
            out.println("welcome "+user);
           }
          else{
              String msg="Login is not successful";
            response.sendRedirect("/examples/jsp/login.jsp?msg="+msg);
          }
    }catch (Exception e){
    e.printStackTrace();
    }
}
}

Hope that it will be helpful for you.

Thanks

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