My First Servlet Page on macOS

JSP Tutorials - Herong's Tutorial Examples

∟My First Servlet Page on macOS

This section provides a tutorial example on how to create the first Servlet Java class to test the Servlet support of the Tomcat Web server on macOS systems.

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

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

herong$ javac -cp /Library/Tomcat/apache-tomcat-9.0.26/lib/servlet-api.jar \
   HelloServlet.java

herong$ ls -l HelloServlet.*
-rw-r--r--  1 herong  staff  791 Jan  8 21:34 HelloServlet.class
-rwxr-xr-x  1 herong  staff  549 Jan  8 21:26 HelloServlet.java

3. Create the "WEB-INF\classes" sub-directory under my application directory on the Tomcat server. Make sure that it has "read" permission for all users.

herong$ cd /Library/Tomcat/apache-tomcat-9.0.26/webapps/herong
herong$ mkdir WEB-INF
herong$ mkdir WEB-INF/classes

4. Save this Servlet bytecode file, HelloServlet.class, to the "WEB-INF\classes" sub-directory. Make sure that it has "read" permission for all users.

herong$ cp HelloServlet.class \
   /Library/Tomcat/apache-tomcat-9.0.26/webapps/herong/WEB-INF/classes

4. Map the Servlet to a URL path name on the Tomcat server by creating the "/Library/Tomcat/apache-tomcat-9.0.26/webapps/herong/WEB-INF/web.xml" file. Make sure that it has "read" permission for all users.

<web-app>
  <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/herong/Hello.servlet" with any browser. The output of my first Servlet class shows up: