Servlet Example

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Let us create a simple servlet example using Eclipse IDE. To create servlet application we need to use following steps:

Environment used:
- JDK
- Eclipse IDE
- Apache Tomcat Server
- Java-api
Open the Eclipse IDE and Go to File Menu ->New->Select Dynamic Web Project.
Enter Project Name click on Next.
Click on Generate web.xml deployment descriptor and click Finish.
Now under the project, click on Java Resources ->select src, right mouse click and select New->Package and type the name as javabeat.net.servlets
Now click on the package javabeat.net.servlets and New ->select Servlet

Type the class name as ServletDemo and click Finish.
Now to add servlet-api jar to project we need to do following steps.
- Right mouse click on Project name, select -> Properties ->select Java Build Path->Click on Add External JAR’s.
- Select servlet-api.jar from Apache Tomcat directory.
- Click on Open and click OK.

Add the following content to the ServletDemo.java:

package javabeat.net.servlets;

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 ServletDemo
 */
public class ServletDemo extends HttpServlet {

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	response.setContentType("text/html");
	PrintWriter out = response.getWriter();

	out.println("<html>");
	out.println("  <head>");
	out.println("    <title>SimpleServlet</title>");
	out.println("  </head>");
	out.println("  <body>");
	out.println("    Hello, World");
	out.println("  </body>");
	out.println("</html>");
	}
	public void destroy(){
	        System.out.println("shutting down....");
}

Details of the above code:

doGet method is used to sent specific amount of data.
ServletRequest is used to collect data which is available with client requested data.
ServletResponse object is used to generate the output content.
ServletException is used to intimate container that request has generated error. IOException is used if input and output error is detected when servlet handles GET request.
destroy () is used to clean up the resources that servlet have initialized.

Edit the web.xml and include the following content to it:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <servlet>
        <servlet-name>ServletDemo</servlet-name>
        <servlet-class>javabeat.net.servlets.ServletDemo</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>ServletDemo</servlet-name>
        <url-pattern>/ServletDemo</url-pattern>
    </servlet-mapping>
</web-app>

Select the class ServletDemo right mouse click->Run As and select Run on Server, an output as shown below should be achieved:

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