Creating and Deploying a Servlet on Tomcat

JSP Tutorials - Herong's Tutorial Examples

∟Creating and Deploying a Servlet on Tomcat

This section provides a tutorial example on how to create a simple Servlet class, compile it and deploy it on the Tomcat server.

To confirm that Apache Tomcat is a Servlet engine or container, I did the following steps to create my first Servlet page:

1. Write the following simple Servlet example in any text editor:

/* HelloServlet.java
 * Copyright (c) 2002 HerongYang.com. All Rights Reserved.
 */
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class HelloServlet extends HttpServlet {
   public void doGet(HttpServletRequest req, HttpServletResponse res)
      throws ServletException, IOException {
      res.setContentType("text/html");
      PrintWriter out = res.getWriter();
      out.println("<html><body>");
      out.println("<p>Hello World! -- From Servlet</p>");
      out.println("</body></html>");
      out.close();
   }
}

2. Save this Servlet class file, HelloServlet.java, to the "classes" folder of the default application folder on the Tomcat server: \local\tomcat\webapps\ROOT\WEB-INF\classes\

3. Compile this Servlet class file into Java bytecode in a command window. Note that "servlet-api.jar" is needed to complete the compilation.

herong> set classpath=\local\tomcat\lib\servlet-api.jar

herong> cd \local\tomcat\webapps\ROOT\WEB-INF\classes

\local\tomcat\webapps\ROOT\WEB-INF\classes>javac HelloServlet.java

\local\tomcat\webapps\ROOT\WEB-INF\classes>dir
   791 HelloServlet.class
   571 HelloServlet.java

4. Map the Servlet to a URL path name on the Tomcat server by editing the "\local\tomcat\webapps\ROOT\WEB-INF\web.xml" file:

<?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_4_0.xsd"
  version="4.0" metadata-complete="true">

  <display-name>Welcome to Tomcat</display-name>
  <description>
     Welcome to Tomcat
  </description>

<!-- Add the following 8 lines to map a Servlet class to a URL -->
    <servlet>
        <servlet-name>Hello</servlet-name>
        <servlet-class>HelloServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Hello</servlet-name>
        <url-pattern>/Hello.servlet</url-pattern>
    </servlet-mapping>

</web-app>

5. Access the Servlet class through the mapped URL "http://localhost:8080/Hello.servlet" with any browser. The output of my first Servlet class shows up: