Context Log Example Using Servlet
This example illustrates about how to use of Context Log in servlet. Context
Log is used to write specified message to server log file when servlet is
called. In the following JSP page (message.jsp) we have simply taken a text area where
user give his/her message and post the form. After posting the form, the servlet ContextLogExample
is called. Source code of the message.jsp is
given below:
Source code of message.jsp:
<%@page language="java" session="true" contentType="text/html;charset=ISO-8859-1"%>
<br>
<form name="frm" method="post" action=../ContextLogExample>
<table border = "0">
<tr align="left" valign="top">
<td>Give your Message:</td>
</tr>
<tr>
<td><TEXTAREA NAME="message" COLS=30 ROWS=6></TEXTAREA></td>
</tr>
<tr align="left" valign="top">
<td><input type="submit" name="submit" value="submit"/></td>
</tr>
</table>
</form>
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Running the jsp page (message.jsp) on this url: http://localhost:8080/JavaExample/JSP/message.jsp
the will displays as below:
In the following servlet (ContextLogExample) we get parameter of jsp page
in "message" variable and set this message to the log file by log()
method of ServletContext interface
The Source code of ContextLogExample.java is given below:
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ContextLogExample extends HttpServlet {
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException{
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String message = request.getParameter("message");
ServletContext context = getServletContext();
if(message == null || message.equals("")){
context.log("No message received:",
new IllegalStateException("Parameter not Found"));
}else{
context.log("Parameter Found: Successfully
received your message: " + message);
}
out.println("<html><head><title>Context Log
Example</title></head><body>");
out.println("<h2><font color='green'>Successfully
send your Message</font></h2>");
out.println("</body></html>");
}
}
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Mapping of servlet (ContextLogExample.java)
in web.xml
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<servlet>
<servlet-name>ContextLogExample</servlet-name>
<servlet-class>ContextLogExample</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ContextLogExample</servlet-name>
<url-pattern>/ContextLogExample</url-pattern>
</servlet-mapping>
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User enters the message in the text area that is sent
to the servlet
(ContextLogExample)
Servlet sets the message in the log file which is shown like below:
Download Source Code
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