CS639 Example servlets delivered with tomcat

To see these, browse to http://sf08.cs.umb.edu:11600/ and follow the link to Example Servlets

 

Source Code for HelloWorld Example

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
 
public class HelloWorld extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws IOException, ServletException
    {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<html>");
        out.println("<head>");
        out.println("<title>Hello World!</title>");
        out.println("</head>");
        out.println("<body>");
        out.println("<h1>Hello World!</h1>");
        out.println("</body>");
        out.println("</html>");
    }
}
 

Execution:  User navigates to (say from link on tomcat’s home page)

        http://sf08.cs.umb.edu:11600/examples/servlets/servlet/HelloWorldExample

 

Browser connects to sf08.cs.umb.edu on TCP port 11600

GET /examples/servlets/servlet/HelloWorldExample HTTP/1.1

…   (header)

 

<html>

<head>

<title>Hello World!</title>

</head>

<h1>Hello World!</h1>

</body>

</html>

 

The browser displays HTML:

Hello World!                                                                      <little image>

 

Note: The actual servlet source code has additional code to supply an image on the right.

 

 

Source Code for Request Info Example

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
 
public class RequestInfo extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws IOException, ServletException
    {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<html>");
        out.println("<body>");
        out.println("<head>");
        out.println("<title>Request Information Example</title>");
        out.println("</head>");
        out.println("<body>");
        out.println("<h3>Request Information Example</h3>");
        out.println("Method: " + request.getMethod());
        out.println("Request URI: " + request.getRequestURI());
        out.println("Protocol: " + request.getProtocol());
        out.println("PathInfo: " + request.getPathInfo());
        out.println("Remote Address: " + request.getRemoteAddr());
        out.println("</body>");
        out.println("</html>");
    }
 
    /**
     * We are going to perform the same operations for POST requests
     * as for GET methods, so this method just sends the request to
     * the doGet method.
     */
 
    public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws IOException, ServletException
    {
        doGet(request, response);
    }
}

Returned HTML:

Request Information Example

Method:

GET

Request URI:

/examples/servlets/servlet/RequestInfoExample    

Protocol:

HTTP/1.1

Path Info:

null

Remote Address:

76.24.21.194

 

Note: For REST, we will use the term URI for the whole string http://server:port/request-path, so above terminology “request URI” is unfortunate but stuck in the API. A request URI for a GET can include a query string. In a POST, any query string information is in the body of the request.

 

Note: Here we see doGet, doPost. Follow the Java EE API link in class web page to see other methods of HttpServlet: doDelete, doHead, doPut, etc. Also see APIs for HttpServletRequest  and HttpServletResponse.  These are the first Java methods we’ve covered that are not in the JSE API (i.e., the normal JDK).