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The following is an authentication form, which validates the Login ID and Password keyed in by the user and returns an appropriate page generated by a Servlet code. First of all you will create one table in M.S Access as shown below:

Table Definitions:

Table Name	: login[SchoolDemo.mdb]
Primary Key	: Nil
Foreign Key	: Nil

Column Definition:

Column Name	Data Type	Width
Loginname	Text	20
Password	Text	20

Table Description:

Column Name	Description
Loginname	Identification of the person filling the Login form.
Password	Password entered by the person

Explanation:

When the user submits the login name and password. A check is made in the table for that user name and password. If the user name and password match a single entry a welcome page will be returned, or else access denied page will be returned.

After create table in M.S. Access database now you will create DSN.

Test Records:
login[SchoolDemo.mdb]

Loginname	Password
laura	cath
mirella	mrsbean
bintu	12345

Following is the source code of the HTML page i.e. Login.html:

<HTML>
 <HEAD>
  <TITLE> SCT's User Authentication Form </TITLE>
 </HEAD>

 <BODY Background="images/grid1.gif">
  <BR><BR>

  <CENTER>
   <H2><B> User's Authentication Page </B></H2>
  </CENTER>

  <FORM Action="../servlets/login" Method="POST">
   <BR><BR>

   <TABLE Border="0" CellPadding="5" CellSpacing="0" Width="400" Align="Center">
    <FONT Color="#000000" Size="2">
    <TR>
     <TD Align="Right">
      <B>Login Name:</B>
     </TD>
     <TD>
      <INPUT Type="Text" Name="Loginid" Size="20">
     </TD>
    </TR>

    <TR>
     <TD Align="Right">
      <B>Password:</B>
     </TD>
     <TD>
      <INPUT Type="Password" Name="Password" Size="20">
     </TD>
    </TR>
    </FONT>
   </TABLE>
   <BR><BR>

   <P></P>
   <P></P>
   <CENTER>
    <Input Type="Submit" Value="Submit" Name="Submit">
    <Input Type="Reset" Value="Reset" Name="Reset">
   </CENTER>
  </FORM>
 </BODY>
</HTML>

The following is the source code for "login.java:

import java.sql.*; import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class login extends HttpServlet { Connection conn; public void service(HttpServletRequest request, HttpServletResponse response) throws IOException { ServletOutputStream out=response.getOutputStream(); String url="jdbc:odbc:MyDsn"; try { String login=request.getParameter("Loginid"); String pass=request.getParameter("Password"); Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); conn=DriverManager.getConnection(url); Statement stmt=conn.createStatement(); ResultSet rs=stmt.executeQuery("select * from login where loginname='" + login + "' and password= '" + pass + "'"); response.setContentType("text/html"); response.setStatus(HttpServletResponse.SC_OK); if(rs.next()==false) { out.println("<BR><BR><BR><BR><BR>"); out.println("<html><head><title>Login check</title></head><body>"); out.println("<CENTER><B>Unknown User</B>"); out.println("<BR><BR>"); out.println("<h3> Access Denied</h3></CENTER>"); out.println("<BR><BR><BR>"); out.println("<CENTER><Input Type=Button Value=Back></CENTER>"); out.println("</body></html>"); } else { out.println("<html><head><title>Login Check</title></head><body>"); out.println("<BR><BR><BR><BR><BR>"); out.println("<CENTER><B>Welcome " + " " + rs.getString("loginname") + "</B></CENTER>"); out.println("<CENTER>"); out.println("<h3> You have been Authenticated</h3></CENTER>"); out.println("<BR><BR><BR>"); out.println("<CENTER><Input Type=Button Value=HOME></CENTER>"); out.println("</body></html>"); } conn.close(); } catch(SQLException SQLExcp) { out.println("SQLException: " + SQLExcp); } catch(ClassNotFoundException clsNotFndExcp) { System.out.println("Cannot find the class: "+ clsNotFndExcp); } } }

To run the above servlet program , first of all run Apache Tomcat from "Start -> All Programs -> Apache Tomcat 4.0 -> Start Tomcat."

Now compile Java Servlet Program using below command as shown diagram 24.22

Diagram 24.22 Compile Java Servlet

Now, copy "SimpleServlet.class" File and then paste it under

"C:/Program Files/Apache Tomcat 4.0/webapps/examples/WEB-INF/classes/"

Now, open your any web browser and type html URL where you saved your login.html file. for example:

Diagram 24.23 Output of Login.html

Diagram 24.23 Output of login.class for a valid username and password

Diagram 24.24 Output of login.class for an invalid username and password

Java Servlet Programming

Creating Java Servlets (Compiling and Running a Java Servlet)

Generic and Http Servlets

Calling a servlet from within an HTML page

Using JDBC In Servlet

User Authentication Form using Java Servlet

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User Authentication Form Using Servlet

Java Servlet Programming

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