Creating a Servlet with Eclipse and Tomcat

ServletDefinition: What is Servlet

Java Servlets are server-side Java program modules that process and answer client requests and implement the servlet interface. It helps in enhancing Web server functionality with minimal overhead, maintenance and support.

A servlet acts as an intermediary between the client and the server. As servlet modules run on the server, they can receive and respond to requests made by the client.

A servlet is integrated with the Java language, it possesses all the Java features such as high portability, platform independence, and security and Java database connectivity.

Environment Used

  • JDK 7
  • Eclipse IDE
  • Apache Tomcat 6.x
  1. Java Installation

Java Installation Tutorial for instructions of how to install JDK 7.

2.  Tomcat Installation

Apache Tomcat Installation Tutorial for instructions of how to install Apache Tomcat.

After the installation test if Tomcat in correctly installed by opening a browser to http://localhost:8080/ .This should open an information page of Tomcat.               Afterwards stop Tomcat. Eclipse needs to start Tomcat itself for its deployments.

3.  Eclipse Installation

Eclipse Installation Tutorial for instructions of how to install Eclipse.

4.  Now we are ready to create Dynamic Web Project.

Creating Dynamic Web Project

To create a Servlet we need to create a new ‘Dynamic Web Project’. Follow following steps:

  • File menu -> New -> Dynamic Web Project

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  • Enter the project name as ‘HelloWorld‘ and make sure the Apache Tomcat v6.0 Target Runtime has been selected with the Dynamic web module version as 2.5 and click on ‘Finish‘ button.

Creating Servlet

  • Project -> New -> Servlet
  • Enter the Class name as HelloServlet
  • Click on ‘Finish‘

The complete source code for the class will now look like this:

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

* Servlet implementation class HelloServlet

*/

public class HelloServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

/**

* @see HttpServlet#HttpServlet()

*/

public HelloServlet()

{

super();

// TODO Auto-generated constructor stub

}

/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

*/

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException

{

// TODO Auto-generated method stub

response.setContentType(“text/html”);

PrintWriter pw = response.getWriter();

pw.println(“<h1>Hello World</h1>”);

}

}

  • response.setContentType(); means we are setting what type of response we are sending back.
  • PrintWriter will be used to write the response, we can get the PrintWriter object from the response object.

Run the Servlet

  • Right click on the ‘HelloServlet.java’ Dynamic Web project -> Run As -> Run on Server. Select the existing ‘Tomcat v6.0 Server at localhost’ and click Finish.

http://localhost:8080/HelloWord/HelloServlet

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Note:The information provided here is best of my knowledge and experience if at all any modifications are to be made please help me with ur valuable suggestion which are always welcome…. 🙂

 

Tomcat Installation on Ubuntu

The Apache tomcat6 installation is done in below versions of Linux, Java

UBUNTU 13.4

JAVA 1.7.0_25

  •  Download apache tomcat tar file from here
  •  Unzip the tar

hduser@archana:~$ tar xzf apache-tomcat-6.0.37.tar.gz

Or

Right click on apache-tomcat-6.0.37.tar.gz and choose extract here option.

  •  Move apache-tomcat-6.0.37 to tomcat6

hduser@archana:~$sudo mv apache-tomcat-6.0.37 /usr/local/tomcat6

  •  Now Configure bashrc file

CATALINA_HOME is path of tomcat extracted folder

JAVA_HOME is path where java is installed

hduser@archana:~$gedit ~/.bashrc

      In bashrc file append the below 2 statements

export JAVA_HOME=/usr/lib/jvm/jdk1.7.0_25

export CATALINA_HOME=/usr/local/tomcat6

Save and exit out of .bashrc. You can make the changes effective by restarting the bashrc file.

hduser@archana:~$ . .bashrc

  • Once we are done with path it’s time to run (start) tomcat

Move to the bin folder

hduser@archana:~$cd /usr/local/tomcat6/bin/

  •  Start tomcat server

hduser@archana:/usr/local/tomcat6/bin$ sh startup.sh

Using CATALINA_BASE:   /usr/local/tomcat6

Using CATALINA_HOME:   /usr/local/tomcat6

Using CATALINA_TMPDIR: /usr/local/tomcat6/temp

Using JRE_HOME:        /usr/lib/jvm/jdk1.7.0_25

Using CLASSPATH:       /usr/local/tomcat6/bin/bootstrap.jar

  • Stop tomcat server

hduser@archana:/usr/local/tomcat6/bin$ sh shutdown.sh

Using CATALINA_BASE:   /usr/local/tomcat6

Using CATALINA_HOME:   /usr/local/tomcat6

Using CATALINA_TMPDIR: /usr/local/tomcat6/temp

Using JRE_HOME:        /usr/lib/jvm/jdk1.7.0_25

Using CLASSPATH:       /usr/local/tomcat6/bin/bootstrap.jar

🙂

How to install MySQL on Ubuntu

The MySql installation is done in below version of Ubuntu.

UBUNTU 13.4

  • First of all, make sure your package management tools are up-to-date. Also make sure you install all the latest software available.

            sudo apt-get update

             sudo apt-get dist-upgrade

  • Install the MySQL server and client packages:

sudo apt-get install mysql-server mysql-client

The apt-get command will also install the mysql-client package which is necessary to login to mysql from the server itself.

During the installation, MySQL will ask you to set a root password.

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  • You can now access your MySQL server like this:

mysql -u root -p

 mysql>

  •  Have fun using MySQL Server 🙂
  • What is mysql server and mysql client

The mysql server package will install the mysql database server which you can interact with using a mysql client. You can use the mysql client to send commands to any mysql server; on a remote computer or your own.

The mysql server is used to persist the data and provide a query interface for it (SQL). The mysql clients purpose is to allow you to use that query interface.

How to install Java in Ubuntu

The JDK 7 installation is done in below version of Ubuntu.

UBUNTU 13.4

  •  Download  from here 32bit or 64bit Linux “compressed binary file” – it has a “.tar.gz” file extension i.e. “[java-version]-i586.tar.gz” for 32bit and “[java-version]-x64.tar.gz” for 64bit
  • Once the download is complete, uncompressed the file using following command

sudo tar -xvf jdk-7u25-linux-i586.tar.gz

JDK 7 package is extracted into /jdk1.7.0_25 directory.

  • Now move the JDK 7 directory to /usr/lib

            sudo mkdir -p /usr/lib/jvm

            sudo mv jdk1.7.0_25/ /usr/lib/jvm/jdk1.7.0_25

  • Now run

sudo update-alternatives –install “/usr/bin/java” “java” “/usr/lib/jvm/jdk1.7.0_25/bin/java” 1

sudo update-alternatives –install “/usr/bin/javac” “javac” “/usr/lib/jvm/jdk1.7.0_25/bin/javac” 1

sudo update-alternatives –install “/usr/bin/javaws” “javaws” “/usr/lib/jvm/jdk1.7.0_25/bin/javaws” 1

  • Run

sudo update-alternatives –config java

You will see output similar one below – choose the number of jdk1.7.0_25

There are 2 choices for the alternative java (providing /usr/bin/java).

 Selection    Path                                           Priority          Status

————————————————————————————–

  0      /usr/lib/jvm/java-7-openjdk-i386/jre/bin/java     1071   auto mode

  1      /usr/lib/jvm/java-7-openjdk-i386/jre/bin/java    1071   manual mode

* 2     /usr/lib/jvm/jdk1.7.0_25/bin/java                       1       manual mode

 Press enter to keep the current choice[*], or type selection number: 2

 

  • Repeat the above step 5 for below commands:

sudo update-alternatives –config javac

sudo update-alternatives –config javaws

  • Check the version of your new JDK 7 installation:

java -version

java version “1.7.0_25”

Java(TM) SE Runtime Environment (build 1.7.0_25-b15)

Java HotSpot(TM) Server VM (build 23.25-b01, mixed mode)

  • Set JAVA_HOME in Ubuntu.

Open the .bashrc

gedit ~/.bashrc

Now add the following to the end of the file.

export JAVA_HOME=/usr/lib/jvm/java-1.7.0_25

export PATH=$PATH:$JAVA_HOME/bin

NOTE: If /usr/lib/jvm/java does not match the actual JAVA_HOME path in your environment, then set the actual JAVA_HOME, where you have installed Java in your machine.

Now, JDK 7 has been successfully installed on your Ubuntu 🙂

Installing Eclipse in Ubuntu

Before installing eclipse IDE you need to check few things.

First, check whether you have Java installed or not. For that you need to run following command in your terminal

hduser@archana:~$ java -version

If you get the java version as a output that means you have java otherwise u need to install java.

  • First download the eclipse tar.gz package from here
  • Use the below command line to extract the tar.gz package.

hduser@archana:~$ tar xzf eclipse-jee-kepler-R-linux-gtk.tar.gz

 Or

you can also use- right click on eclipse-jee-kepler-R-linux-gtk.tar.gz and chose extract here option.

  • Move the extracted eclipse in the /opt/ folder.

hduser@archana:~$ sudo mv eclipse /opt/

  • Create a desktop file and place it into /usr/share/applications

hduser@archana:~$ gedit /usr/share/applications/eclipse.desktop

and copy the following to the eclipse.desktop file

[Desktop Entry]

Name=Eclipse

Type=Application

Exec=/opt/eclipse/eclipse

Terminal=false

Icon=/opt/eclipse/icon.xpm

Comment=Integrated Development Environment

NoDisplay=false

Categories=Development;IDE

Name[en]=eclipse.desktop

  •  Create a symlink in /usr/local/bin using

hduser@archana:~$ cd /usr/local/bin

hduser@archana:~$ sudo ln -s /opt/eclipse/eclipse

  •   Now goto /usr/share/applications and find eclipse.desktop file for launching eclipse , you can drag this file to the launcher.
  • Start Eclipse
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