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.
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