The document discusses servlets and provides details about: - The servlet API and its packages/classes/interfaces for creating and managing servlets - The lifecycle methods of servlets including init(), service(), destroy() - How to create a simple servlet that displays the current date - Configuring servlets using web.xml or annotations - The role of the web container in providing runtime environment and managing the lifecycle of servlets

1. Riza Muhammad Nurman ADP
Click to edit Master title style
Chapter 2
on
Advanced Programming
FACULTY
Riza Muhammad Nurman
Exploring the java Servlet Technology

2. Riza Muhammad Nurman ADP
Click to edit Master title styleContent
• Introduce servlet
• Implement servlets

3. Riza Muhammad Nurman ADP
Click to edit Master title styleIntroduction to Servlets
• Web  used as a medium entertainment, business,
and socializing
• Ex: Google website
• Servlet is a Java program that runs on the server side
• Servlet features:
– Efficient :
• Servlets provide faster response to the client requests as it is loaded
only once in the Web server memory
– Asynchronous support :
• Servlet supports asynchronous programming that enables it to serve
multiple client requests and generate responses simultaneously

4. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Servlet API
• To create and manage
servlets, various interfaces,
classes, and methods are
defined in the Servlet API
• Classes and interafaces of the
Servlet API are available in
the following packages:
– javax.servlet
– javax.servlet.http
Servlet API
javax.servlet javax.servlet.http
GenericServlet
ServletException
Servlet
RequestDispatcher
ServletConfig
ServletRequest
ServletResponse
ServletContext
AsyncContext
HttpServlet
Cookie
HttpServletRequest
HttpServletResponse
HttpSession
Packages
Classes
Interfaces
The Servlet API Hierarchy

5. Riza Muhammad Nurman ADP
Click to edit Master title styleThe javax.servlet Package
Interface Description
Servlet It provides the methods that all servlets must implement
ServletConfig It provides information to the servlets during the servlet initialization
ServletContext It provides methods, which is used by the servlets to communicate
with the Web container
ServletRequest It provides the client request information to the servlet
ServletResponse It helps the servlet in sending the response to the client
RequestDispatcher It receives a request from a client and sends it to any other resource,
such as a servlet, an HTML page, or a JSP page
AsyncContext It provides the methods to handle multiple client requests
asynchronously

6. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Methods of the Servlet Interface
Interface Description
void init(ServletConfig config) throws
ServletException
It is called by the servlet container to indicate to a
servlet that the servlet is being placed into service
ServletConfig getServletConfig() Returns a ServletConfig object, which contains
initialization and startup parameters for this servlet
String getServletInfo() Returns information about the servlet, such as author,
version, and copyright
void service(ServletRequest request,
ServletResponse response) throws
ServletException, IOException
It is Called by the servlet container to allow the servlet
to respond to a request
void destroy() Called by the servlet container to indicate to a servlet
that the servlet is being taken out of service

7. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Methods of the ServletRequest Interface
Interface Description
String getParameter(String
paramName)
Returns a String object that specifies the value of a
particular request parameter
public String[]
getParameterValues(String
paramName)
Returns an array of String objects that contains all the
values of the request parameter
public Enumeration
getParameterNames()
Returns an Enumeration object containing all the
parameter names as String objects that `request
contains
public String getRemoteHost() Returns a String object that specifies the full-qualified
name of the computer from which the request is sent
public String getRemoteAddr() Returns a String object that specifies the IP address of
the computer from which the request is sent

8. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Methods of the ServletResponse Interface
Interface Description
public ServletOutputStream
getOutputStream() throws IOException
Returns an object of the ServletOutputStream class
that represents an output stream to send binary data
as response
public PrintWriter getWriter() throws
IOException
Returns an object of the PrintWriter class that the
servlet uses to send character data as response
public void setContentType(String
type)
Sets the MIME type for a servlet response. Some of the
MIME types are text/lain, image/jpeg, and text/html.

9. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Interfaces of the javax.servlet.http Package
Interface Description
HttpServletRequest It extends the ServletRequest interface to represent
the request information being sent to the HTTP
servlets by an HTTP client
HttpServletResponse It extends the ServletResponse interface and provides
methods to handle response, status codes, and
response headers of the servlets that communicate
using HTTP
HttpSession It provides mechanism that helps in identifying a client
across multiple requests

10. Riza Muhammad Nurman ADP
Click to edit Master title styleCode Snippet “MyServlet”
1. import javax.servlet.http.HttpServlet;
2. import javax.servlet.http.HttpServletRequest;
3. import javax.servlet.http.HttpServletResponse;
4. public class MyServlet extends HttpServlet {
5. protected void doGet(HttpServletRequest request, HttpServletResponse
response)
6. throws ServletException, IOException {
7.
8. }
9. protected void doPost(HttpServletRequest request, HttpServletResponse
response)
10. throws ServletException, IOException {
11.
12. }
13. }
14. }

11. Riza Muhammad Nurman ADP
Click to edit Master title styleUnderstanding the Web Container
• Web Container is a component of the Web server which
provides the run-time environment for executing the servlets
• Web container implements the Servlet APIs
– Communication Support : The Web container provides communication
support that a servlet can communicate with the Web server
– Lifecycle Management : The Web container manages the lifecycle of the
servlets.
– Multithreading Support : The Web container provides multithreading
support for every servlet
– Declarative Security : The Web container defines the security
constraints that specify that only the authorized users can access the
deployed servlets
– JSP Support : The Web container compiles and translates the JSP pages
into the servlet class files, which are then used to process the requests
of a client

12. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Web Container Architecture

13. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Web Container Architecture - 2

14. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Web Container Architecture - 3

15. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Web Container Architecture - 4

16. Riza Muhammad Nurman ADP
Click to edit Master title styleThe Web Container Architecture - 5

17. Riza Muhammad Nurman ADP
Click to edit Master title styleLife Cycle of a Servlet
• init()
– The method is called during initialization phase of the servlet life cycle
• service()
– To process client request
• destroy()
– The method marks the end of the life cycle of a servlet
public void init(ServletConfig config) throws ServletException {
...
}
protected void service(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
...
}
public void destroy() {
...
}

18. Riza Muhammad Nurman ADP
Click to edit Master title styleImplementing Servlets – Create a New project
Pilih kategori
Java Web
Pilih Projects
Web Application

19. Riza Muhammad Nurman ADP
Click to edit Master title styleWeb Application Structure
• The root directory
– Contains static resources : HTML files, JSP
files, and image files
• The WEB-INF directory inside the root
directory
– Contains the application deployment
descriptor file, web.xml, which stores
various configurations of a Web
application
• The classes directory
– Contains the class files of the application
• The lib directory
– Contains Java Archive (JAR) files of
libraries

20. Riza Muhammad Nurman ADP
Click to edit Master title styleindex.html
1. <!DOCTYPE html>
2. <!--
3. To change this license header, choose License Headers in Project Properties.
4. To change this template file, choose Tools | Templates
5. and open the template in the editor.
6. -->
7. <html>
8. <head>
9. <title>TODO supply a title</title>
10. <meta charset="UTF-8">
11. <meta name="viewport" content="width=device-width, initial-scale=1.0">
12. </head>
13. <body>
14. <div>TODO write content</div>
15. </body>
16. </html>

21. Riza Muhammad Nurman ADP
Click to edit Master title styleCreating a Servlet
• Packages : myservlet
• Servlet Name : CurrentData

22. Riza Muhammad Nurman ADP
Click to edit Master title styleConfiguring a Servlet Using DD File
1. <?xml version="1.0" encoding="UTF-8"?>
2. <web-app version="3.1"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-
instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
3. <servlet>
4. <servlet-name>CurrentDate</servlet-name>
5. <servlet-class>myservlet.CurrentDate</servlet-class>
6. </servlet>
7. <servlet-mapping>
8. <servlet-name>CurrentDate</servlet-name>
9. <url-pattern>/CurrentDate</url-pattern>
10. </servlet-mapping>
11. <session-config>
12. <session-timeout>
13. 30
14. </session-timeout>
15. </session-config>
16. </web-app>

23. Riza Muhammad Nurman ADP
Click to edit Master title styleConfiguring a Servlet Using Annotations
1. @WebServlet(name =
"CurrentDate", urlPatterns =
{"/CurrentDate"})
2. public class CurrentDate
extends HttpServlet {
3. …
4. }

24. Riza Muhammad Nurman ADP
Click to edit Master title styleServlet CurrentDate

25. Riza Muhammad Nurman ADP
Click to edit Master title styleprocessRequest Method
1. protected void processRequest(HttpServletRequest request,
HttpServletResponse response)
2. throws ServletException, IOException {
3. response.setContentType("text/html;charset=UTF-8");
4. try (PrintWriter out = response.getWriter()) {
5. /* TODO output your page here. You may use following sample code. */
6. out.println("<!DOCTYPE html>");
7. out.println("<html>");
8. out.println("<head>");
9. out.println("<title>Servlet CurrentDate</title>");
10. out.println("</head>");
11. out.println("<body>");
12. out.println("<h1>Servlet CurrentDate at " + request.getContextPath() +
"</h1>");
13. out.println("</body>");
14. out.println("</html>");
15. }
16. }

26. Riza Muhammad Nurman ADP
Click to edit Master title styleOthers Method
1. @Override
2. protected void doGet(HttpServletRequest request, HttpServletResponse
response)
3. throws ServletException, IOException {
4. processRequest(request, response);
5. }
6. @Override
7. protected void doPost(HttpServletRequest request,
HttpServletResponse response)
8. throws ServletException, IOException {
9. processRequest(request, response);
10. }
11. @Override
12. public String getServletInfo() {
13. return "Short description";
14. }

27. Riza Muhammad Nurman ADP
Click to edit Master title styleSample
1. protected void processRequest(HttpServletRequest request, HttpServletResponse response)
2. throws ServletException, IOException {
3. response.setContentType("text/html;charset=UTF-8");
4. try (PrintWriter out = response.getWriter()) {
5. /* TODO output your page here. You may use following sample code. */
6. out.println("<!DOCTYPE html>");
7. out.println("<html>");
8. out.println("<head>");
9. out.println("<title>Hello World</title>");
10. out.println("</head>");
11. out.println("<body>");
12. out.println("<h1>"+ new java.util.Date() +"</h1>");
13. out.println("</body>");
14. out.println("</html>");
15. }
16. }

28. Riza Muhammad Nurman ADP
Click to edit Master title style