IP : Java Servlet. Code for displaying "Hello World"

First install tomcat apache server using this post :

http://semlabs.blogspot.com/2015/09/installing-tomcat-server.html

I am assuming you have your tomcat files in /opt/ , or else, change the path accordingly in the below steps and replace "/opt/".

Put this "hello" folder in /opt/tomcat/webapps/

hello - code.

The above folder contains all the code needed to print "Hello World" in your server response page.

To start tomcat server, type these commands in the terminal :

cd /opt/tomcat/bin/

./startup.sh

and type this in your browser :

http://localhost:8080/hello/HelloWorld

This should print "Hello World".

Here "hello" is the web-app , and "HelloWorld" is the url map for the servlet class file, which is also named "HelloWorld".

This is how I coded this Servlet :

• Created a folder called "hello" in /opt/tomcat/webapps
• Created a folder called "WEB-INF" inside "hello" folder
• Created two folders called "classes" and "src" in "WEB-INF" folder.
• The "WEB-INF" and "classes" folders are very important and must be named same way. I mean, it is case sensitive, and is important.
• To understand the hierarchy in a better manner, download my "hello" folder!
• Then created HelloWorld.java and coded it based on Servlet programming and placed it in "src" folder.
• Created web.xml and defined the servlet name, servlet class name and defined the mapping.
• Compiled the HelloWorld.java like this :
  
  
       javac -cp /opt/tomcat/lib/servlet-api.jar HelloWorld.java

Placed the HelloWorld.class file produced the previous step in "classes" folder.

Started the server using commands mentioned above and checked the output.

To know more about what each of these things mean, and to also know how to code it, look at this pdf by tutorialspoint :

Servlets

For any doubts or problems, mail me. This is the most basic Servlet program. This should give you a feel of how to code Servlets! :)