Finding value of initial parameter in servlet

Satyapriya Nayak
Aug 30, 2011
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Finding value of initial parameter in servlet.rar

This is a process to read value from web.xml file into the servlet.The servlet can get a value from its user without having an html form.The value of a parameter can be fetched from web.xml file by using getInitParameter() method of servlet.The initial parameter can be defined in web.xml file by using the following tags given below as,

<init-param>,<param-name>,<param-value>
<servlet>
<servlet-name>This contains a name to refer the servlet inside this file </servlet-name>
<servlet-class>This contains class name of the servlet</servlet-class>
<init-param>
<param-name>This contains name of the initial parameter</param-name>
<param-value> This contains value of the initial parameter </param-value>
</init-param>
</servlet>

Example

//using initial parameter in a servlet

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class initParamServ extends HttpServlet
{
    public void doGet(HttpServletRequest req,HttpServletResponse res)throws IOException,ServletException
    {
       String s1=getInitParameter("gp");
       res.setContentType("text/html");
       PrintWriter out=res.getWriter();
       out.println("<Html><body bgcolor='CYAN'>");
       out.println("<H1><font color='blue'>Today's Gold price<blink>"+s1+"</blink></font></h1>");
       out.println("</Body></html>");
    }
}

Storing and Compiling

Store the file inside class folder of the contex (E:\Servlet\WEB-INF\classes).

Compile the file as below

javac -cp servlet-api.jar number.java (for tomcat 6.0)

complile Servlet

Setting in web.xml file

Note: - Note the Highlighted or bold portion in the below web.xml file, to be added.

<?xml version="1.0" encoding="ISO-8859-1" ?> -

<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>initParamServ</servlet-name>
   <servlet-class>initParamServ</servlet-class>
<init-param>
   <param-name>gp</param-name>
   <param-value>21500</param-value>
</init-param>
</servlet>
   <servlet-mapping>
   <servlet-name>initParamServ</servlet-name>
   <url-pattern>/initParamServ</url-pattern>
</servlet-mapping>
</web-app>

Running it in web browser

Please use Mozilla Firefox browser to blink the value because Internet Explorer do not support <blink></blink> tag property.

First start the Apache tomcat 6.0,

Here x is the context path location, which we have to give in the server.xml file, which is present inside Tomcat installation directory (E:\Program Files\Apache Software Foundation\Tomcat 6.0\conf)

Server.xml settings

Note: - In the below server.xml file we have to specify the context path as below.

<Context path="/x" docBase="E:\Servlet" reloadable="true" debug="0" />

server.xml file

<?xml version='1.0' encoding='utf-8'?>


<Server port="8005" shutdown="SHUTDOWN">


<Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />

<Listener className="org.apache.catalina.core.JasperListener" />

<Listener className="org.apache.catalina.mbeans.ServerLifecycleListener" />
<Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />


<GlobalNamingResources>
    
    <Resource name="UserDatabase" auth="Container"
              type="org.apache.catalina.UserDatabase"
              description="User database that can be updated and saved"
              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
              pathname="conf/tomcat-users.xml" />
</GlobalNamingResources>


<Service name="Catalina">

    
    
    
    <Connector port="8082" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />
    
    
    
    

    
    <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />
    

    
    <Engine name="Catalina" defaultHost="localhost">

      
      

      
      

      
      <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
             resourceName="UserDatabase"/>

      
      <Host name="localhost" appBase="webapps"
            unpackWARs="true" autoDeploy="true"
            xmlValidation="false" xmlNamespaceAware="false">

        
        

        
        
      <Context path="/x" docBase="E:\Servlet" reloadable="true" debug="0" />
            </Host>
    </Engine>
</Service>
</Server>