// File: SampleServlet.java
// Simple servlet example that tells user how many times it has been invoked
// and the last time it was invoked.
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
//import java.math.*;
/**
* Sample Servlet
*
* This servlet returns "Hello World" and the number of times
* the servlet has been requested.
*/
public class SampleServlet extends HttpServlet
{
int numRequests = 0; //number of times servlet requested
String lastRequest = (new java.util. Date()).toString(); //last request
Properties prop = null;
/**
* init() is called when the servlet is first loaded. Use this
* method to initialize resources.
*
* This method reads (from a properties file) the number of
* times the servlet has been requested and initializes the
* numRequests variable.
*/
public void init() throws ServletException
{
prop = new Properties(); //create new Properties object
try
{
//create a file object pointing to the properties file
File file = new File("SampleServlet.properties");
//determine if the properties file exists
if (file.exists())
{
//get an input stream to the properties file
FileInputStream fileIn = new FileInputStream(file);
prop.load(fileIn); //load the properties object from file
//initialize the numRequests variable, default to zero
numRequests = Integer.parseInt(
prop.getProperty("RequestCount", "0"));
//initialize lastRequest, default to current date/time
lastRequest = prop.getProperty("LastRequest",
(new java.util.Date()).toString());
}
else
{
//properties file doesn't exist, use default values
}
}
catch (Exception e)
{
//if unable to read file, use default values
}
}
/**
* service() is called with each client request.
*/
public void service(HttpServletRequest request,
HttpServletResponse response) throws ServletException,
IOException
{
//set MIME type for HTTP header to HTML
response.setContentType("text/html");
//get a handle to the output stream
PrintWriter out = response.getWriter();
//send HTML response to client
out.println("");
out.println("Sample Servlet");
out.println("");
out.println("Hello World!
");
out.println("This servlet has been requested " +
numRequests++ + " time(s).");
out.println("
Last requested at " + lastRequest + ".");
out.println("");
lastRequest = (new java.util.Date()).toString(); //update last request
out.close(); //always close the output stream
connection.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
/**
* getServletInfo() allows the server to query this servlet for
* information regarding its name, version, and brief
* description.
*/
public String getServletInfo()
{
return "Sample Servlet version 1.1";
}
/**
* Destroy is called before the server unloads the servlet. Use
* this method to release any resources held by the servlet and
* other housekeeping chores.
*
* This method stores (in a properties file) the number of
* times the servlet has been requested.
*/
public void destroy()
{
try
{
//create a file object pointing to the properties file
File file = new File("SampleServlet.properties");
//get an output stream to the properties file
FileOutputStream fileOut = new FileOutputStream(file);
//store the request count in the properties object
prop.put("RequestCount", Integer.toString(numRequests));
//store the last request date/time in the properties object
prop.put("LastRequest", lastRequest);
//write the properties object data to the properties file
prop.store(fileOut, "SampleServlet Storage File");
}
catch (Exception e)
{
//if there is an error writing to file, ignore it
}
}
}