Table of Contents
Introduction
Servlets are Java classes that service HTTP requests. Servlet programs are embedded in web browsers. Below are examples of a few Servlet Programs.
Example 1
The following program is a Servlet that will print out a text on a web browser. For this example, we will choose the following text: “This was a Java Servlet Example”.
Java Code
import java.io.*; import javax.servlet.*; import javax.servlet.http.*; // Extend HttpServlet class public class SampleProg extends HttpServlet { private String message; public void init() throws ServletException { message = " This was a Java Servlet Example "; } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // Set response content type response.setContentType("text/html"); // Here the text is printed out using the <h1/> header type PrintWriter out = response.getWriter(); out.println("<h1>" + message + "</h1>"); } public void destroy() { //An empty method means no action is performed here } }
Web.xml file
<servlet> <servlet-name> SampleProg </servlet-name> <servlet-class> SampleProg </servlet-class> </servlet> <servlet-mapping> <servlet-name> SampleProg </servlet-name> <url-pattern> /SampleProg </url-pattern> </servlet-mapping>
Example 2
This is also an example of a servlet that will print out a text as output using a web browser. Let us take the text “Hello World” in this case.
Java Code
import javax.servlet.http.*; import javax.servlet.*; import java.io.*; public class HelloWorld extends HttpServlet { public void doGet(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException { res.setContentType("text/html"); PrintWriter pw=res.getWriter(); pw.println("<html><body>"); pw.println("Hello World"); pw.println("</body></html>"); pw.close();//closing the stream } } Web.xml file <web-app> <servlet> <servlet-name> User </servlet-name> <servlet-class> HelloWorld </servlet-class> </servlet> <servlet-mapping> <servlet-name> User </servlet-name> <url-pattern> /welcome </url-pattern> </servlet-mapping> </web-app>
OUTPUT
To get an output, open your web browser and write in the following format: http://hostname:portno/contextroot/urlpatternofservlet
Example: http://localhost:9999/demo/welcome.
0 Comments