Storing Compilation And Deployment of a Java Servlet

Satyapriya Nayak
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Servlet: It is technology to create dynamic WebPages. This is a Java program, which resides in a web server to process requests from the user and to provide a dynamic response to users.

Storing compilation and deployment of servlet

Store the servlet file inside the "classes" folder of the context for predefined context (root) the classes folder required to be created inside the WEB-INF folder.
For compilation of the servlet files use servlet-api.jar in classpath option of javac command. This jar file contains the package used by the servlet files. This jar file can be found inside the installation folder of the tomcat/lib folder.
Deployment: This is a process to create an url for the servlet. The user will use the url to access the servlet. This can be done by providing a few tags in the web.xml file. The tags are as follows:

In web.xml file present side to classes folder:

<servlet>
        <servlet-name>name</servlet-name>
        <servlet-class>class</servlet-class>
    </servlet>
<servlet-mapping>
        <servlet-name>name</servlet-name>
        <url-pattern>/ url-pattern </url-pattern>
    </servlet-mapping>

Program

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class httpserv extends HttpServlet
{
public void doGet(HttpServletRequest req ,HttpServletResponse res)throws IOException ,ServletException
{
PrintWriter out = res.getWriter();
res.setContentType("text/html");
out.println("<html><body>");
out.println("<h1> First servlet</h1>");
out.println("</body></html>");
}
}

How to run this program

First create a folder named Servlet in any drive (here e: drive). Inside that folder create a WEB-INF folder (all letters will be caps mandatory). Copy a web.xml file from the (E:\Program Files\Apache Software Foundation\Tomcat 6.0\conf) folder. Again inside the WEB-INF folder, create a folder named classes. In the classes folder we will store the Servlet files by their class name; here httpserv.java. Copy the servlet-api.jar (E:\Program Files\Apache Software Foundation\Tomcat 6.0\lib) file in classes folder.

Web.xml setting:

<?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>httpserv</servlet-name>
<servlet-class>httpserv</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>httpserv</servlet-name>
<url-pattern>/httpserv</url-pattern>
</servlet-mapping

</web-app>

Context path setting: Move to (E:\Program Files\Apache Software Foundation\Tomcat 6.0\conf) folder and open server.xml file. Create a context path (any name) and docBase="E:\Servlet" (this is the folder path where we are storing the (WEB-INF\classes) servlet files).

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

<?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="8081" 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="/javaservlet" docBase="E:\Servlet" reloadable="true" debug="0" />

</Host>
</Engine>
</Service>
</Server>

Compiling

javac -cp servlet.jar httpserv.java (for tomcat 4.0)
javac -cp servlet-api.jar httpserv.java (for tomcat 6.0)

cp means classpath

Servlet