Hidden field:
This is a process to store information present in the current request in a form
field called a hidden field. Whenever a form containing a hidden field gets
submitted then the destination servlet can find the value of the hidden field by using the getParameter() method of the request.
Example: - Servlet to accept name of the user as first name and last name
and showing the full name using a hidden field.
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class hidden extends HttpServlet
{
public void doGet(HttpServletRequest req,HttpServletResponse res)throws
IOException,ServletException
{
String s1=req.getParameter("t1");
String s2=req.getParameter("t2");
PrintWriter out=res.getWriter();
out.println("<html><body>");
if(s1 ==null)
{
out.println("<form>");
out.println("<h1>FName<input type='text' name='t1'></h1>");
out.println("<input type='submit' value='submit'>");
out.println("</form>");
}
else if(s2 ==null)
{
out.println("<form>");
out.println("<h1>LName<input type='text' name='t2'></h1>");
out.println("<input type='hidden' name='t1' value='"+s1+"'>");
out.println("<input type='submit' value='submit'>");
out.println("</form>");
}
else
{
out.println("<h1>Welcome "+s1+" "+s2+"</h1>");
}
out.println("</body></html>");
}
}
Web.xml settings
<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
Licensed to the Apache Software Foundation (ASF) under one or more contributor
license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed
under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and
limitations under the License.
-->
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
<servlet>
<servlet-name>hidden</servlet-name>
<servlet-class>hidden</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>hidden</servlet-name>
<url-pattern>/hidden</url-pattern>
</servlet-mapping>
</web-app>
Compile
javac -cp servlet-api.jar hidden.java (for tomcat 6.0)
![Hidden field in Servlet]()
Running in web-browser
Run the tomcat then write the below line in the URL
Here test is the Context path, which we mentioned in the server.xml file, which
is present in (E:\Program Files\Apache Software Foundation\Tomcat 6.0\conf)
directory.
http://localhost: 8081/test/hidden
![Hidden field in Servlet]()
Thanks for reading.