The web application structure involving the WEB-INF subdirectory is standard to all Java web applications and specified by the servlet API specification. Given a top-level directory name of myapp. Here is how this directory structure looks like −

/myapp

/images

/WEB-INF

/classes

/lib

The WEB-INF subdirectory contains the application’s deployment descriptor, named web.xml. All the HTML files should be kept in the top-level directory which is myapp. For admin user, you would find ROOT directory as parent directory.

Creating Servlets in Packages

The WEB-INF/classes directory contains all the servlet classes and other class files, in a structure that matches their package name. For example, If you have a fully qualified class name of com.myorg.MyServlet, then this servlet class must be located in the following directory −

/myapp/WEB-INF/classes/com/myorg/MyServlet.class

Following is the example to create MyServlet class with a package name com.myorg

// Name your package

package com.myorg;

// Import required java libraries

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

public class MyServlet extends HttpServlet {

private String message;

public void init() throws ServletException {

// Do required initialization

message = “Hello World”;

}

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// Set response content type

response.setContentType(“text/html”);

// Actual logic goes here.

PrintWriter out = response.getWriter();

out.println(“<h1>” + message + “</h1>”);

}

public void destroy() {

// do nothing.

}

Compiling Servlets in Packages

There is nothing much different to compile a class available in package. The simplest way is to keep your java file in fully qualified path, as mentioned above class would be kept in com.myorg. You would also need to add this directory in CLASSPATH.

Assuming your environment is setup properly, go in <Tomcat-installationdirectory>/webapps/ROOT/WEB-INF/classes directory and compile MyServlet.java as follows

$ javac MyServlet.java

If the servlet depends on any other libraries, you have to include those JAR files on your CLASSPATH as well. I have included only servlet-api.jar JAR file because I’m not using any other library in Hello World program.

This command line uses the built-in javac compiler that comes with the Sun Microsystems Java Software Development Kit (JDK). For this command to work properly, you have to include the location of the Java SDK that you are using in the PATH environment variable.

If everything goes fine, above compilation would produce MyServlet.class file in the same directory. Next section would explain how a compiled servlet would be deployed in production.

Packaged Servlet Deployment

By default, a servlet application is located at the path <Tomcat-installationdirectory>/webapps/ROOT and the class file would reside in <Tomcat-installationdirectory>/webapps/ROOT/WEB-INF/classes.

If you have a fully qualified class name of com.myorg.MyServlet, then this servlet class must be located in WEB-INF/classes/com/myorg/MyServlet.class and you would need to create following entries in web.xml file located in <Tomcat-installationdirectory>/webapps/ROOT/WEB-INF/

<servlet-name>MyServlet</servlet-name>

<servlet-class>com.myorg.MyServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>MyServlet</servlet-name>

<url-pattern>/MyServlet</url-pattern>

</servlet-mapping>

Above entries to be created inside <web-app>…</web-app> tags available in web.xml file. There could be various entries in this table already available, but never mind.

You are almost done, now let us start tomcat server using <Tomcat-installationdirectory>\bin\startup.bat (on windows) or <Tomcat-installationdirectory>/bin/startup.sh (on Linux/Solaris etc.) and finally type http://localhost:8080/MyServlet in browser’s address box. If everything goes fine, you would get following result −

Hello World

So, this brings us to the end of blog. This Tecklearn ‘Creating Servlets in Packages’ blog helps you with commonly asked questions if you are looking out for a job in Java Programming. If you wish to learn Servlets and build a career Java Programming domain, then check out our interactive, Java and JEE Training, that comes with 24*7 support to guide you throughout your learning period. Please find the link for course details:

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Java Fundamentals
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Various components of Java language
Benefits of Java over other programming languages
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Installation and IDE’s for Java Programming Language

Installation of Java
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Data types, Operations, Compilation process, Class files, Loops, Conditions
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Object Oriented Programming in Java
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String Handling –String Class
Java Packages

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Wrapper Classes and Inner Classes: Integer, Character, Boolean, Float etc
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Java Database Connectivity (JDBC)

Introduction to SQL: Connect, Insert, Update, Delete, Select
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Java Enterprise Edition – Servlets

Introduction to J2EE
Client Server architecture
URL, Port Number, Request, Response
Need for servlets
Servlet fundamentals
Setting up a web project in Eclipse
Configuring and running the web app with servlets
GET and POST request in web application with demo
Servlet lifecycle
Servlets Continued
Session tracking and filter
Forward and include Servlet request dispatchers

Java Server Pages (JSP)

Fundamentals of Java Server Page
Writing a code using JSP
The architecture of JSP
JSP Continued
JSP elements: Scriptlets, expressions, declaration
JSP standard actions
JSP directives
Introduction to JavaBeans
ServletConfig and ServletContext
Servlet Chaining
Cookies Management
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Introduction to Hibernate
Introduction to ORM
ORM features
Hibernate as an ORM framework
Hibernate features
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Basic APIs needed to do CRUD operations with Hibernate
Hibernate Architecture

POJO (Plain Old Java Object)

POJO (Plain Old Java Object)
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