Java Servlets

1
Java Servlets

• A servlet is just a Java class that runs on a
  server
• A servlet (for a web application) extends the
  HttpServlet abstract class
• public class ServletClassName extends HttpServlet
• // code here

2
Java Servlets

• The servlet is part of a package
• ? we need to include a package statement at the
  beginning of the file for the servlet class
• Code inside the Java class is Java code
• No special tags like in a JSP
• ? we need to import the appropriate classes

3
Java Servlets classes to import

• Typically, we need to import the following
  classes
• HttpServlet
• HttpServletRequest
• // JSP remember the implicit object request
• HttpServletResponse
• // JSP remember the implicit object response
• .

4
Java Servlets classes to import

• PrintWriter
• // JSP remember the implicit object out
• IOException, ServletException
• / Some methods (which we will override) of the
  HttpServlet class throw these two exceptions /

5
Java Servlets Classes to import
6
Java Servlets

• package packageName
• import javax.servlet.http.Servlet
• import javax.servlet.http.HttpServletRequest
• import javax.servlet.http.HttpServletResponse
• import java.io.PrintWriter
• import java.io.IOException
• import javax.servlet.ServletException
• // other import statements as necessary
• public class ServletClassName extends HttpServlet
• // code here

7
Java Servlets

• package packageName
• // Using bulk import statements
• import javax.servlet.http.
• import java.io.
• import javax.servlet.ServletException
• // other import statements as necessary
• public class ServletClassName extends HttpServlet
• // code here

8
Java Servlets

• Our servlet extends the abstract class
  HttpServlet (javax.servlet.http package)
• HttpServlet extends the abstract class
  GenericServlet (javax.servlet package)
• GenericServlet extends Object (java.lang package)
• ? A number of methods are inherited from these
  classes by our servlet class