1. Copyright © 2002 ProsoftTraining. All rights reserved.
Java Servlets

2. Copyright © 2002 ProsoftTraining. All rights reserved.
Lesson 1:
Introduction
to Java Servlets

3. Objectives
• Describe the differences between servlets and
other Web application technologies
• Explain the difference between the GET and
POST methods of making an HTTP request
• Create a simple servlet using GET
• Create a simple servlet using POST
• Define a simple deployment descriptor

4. Introduction
to Web Applications
• Web application technologies
– Common Gateway Interface (CGI)
– Server extensions
– Server-side scripting
– JavaServer Pages
– Java servlets

5. Hypertext
Transfer Protocol
• The GET method
• The POST method
• Additional methods

6. Writing a
Simple Servlet
javax.servlet.Servlet
GenericServlet HttpServlet

7. Responding
to Form Data
• FormServlet
• getParameter method
• Using the POST method

8. Deployment
Descriptors
• XML files conforming to Sun Microsystems
DTD
– Describes servlets contained within a Web
application

9. Summary
 Describe the differences between servlets and
other Web application technologies
 Explain the difference between the GET and
POST methods of making an HTTP request
 Create a simple servlet using GET
 Create a simple servlet using POST
 Define a simple deployment descriptor

10. Copyright © 2002 ProsoftTraining. All rights reserved.
Lesson 2:
The Servlet Life Cycle

11. Objectives
• Describe the servlet life cycle
• Create init and destroy methods
• Retrieve servlet initialization parameters
• Use the SingleThreadModel interface
• Retrieve CGI environment variables
• Retrieve and use the ServletContext object
• Use temporary files

12. The
Multithreaded Model
• Servlets typically operate in a multithreaded
environment
– The Web server usually instantiates only
one instance of a servlet to serve all clients
• Deployment descriptors and the multithreaded
model

13. The
Single Thread Model
• The Web server guarantees that no two threads
will ever operate concurrently on the same servlet
instance
• To designate servlets to use the single thread
model, implement the following interface:
– javax.servlet.SingleThreadModel

14. The init
and destroy Methods
• The init method
– Initialization parameters and the
deployment descriptor
• The destroy method

15. CGI
Environment Variables
• AUTH_TYPE
• CONTENT_LENGTH
• CONTENT_TYPE
• HTTP_ACCEPT
• HTTP_REFERER
• HTTP_USER_AGENT
• PATH_INFO
• PATH_TRANSLATED
• QUERY_STRING
• REMOTE_ADDR
• REMOTE_HOST
• REMOTE_USER
• REQUEST_METHOD
• SCRIPT_NAME
• SERVER_NAME
• SERVER_PROTOCOL
• SERVER_PORT

16. The ServletContext
• Methods for obtaining server information
• Using temporary files

17. Summary
 Describe the servlet life cycle
 Create init and destroy methods
 Retrieve servlet initialization parameters
 Use the SingleThreadModel interface
 Retrieve CGI environment variables
 Retrieve and use the ServletContext object
 Use temporary files

18. Copyright © 2002 ProsoftTraining. All rights reserved.
Lesson 3:
Responding to a Request

19. Objectives
• Use client-side caching
• Use client pull to update a client
• Redirect the client to another URL
• Use persistent connections
• Use response status codes
• Return a file to a client
• Dynamically generate images

20. Controlling
the Client
• Using client-side caching
• Using client pull
• Redirecting the client

21. Persistent
Connections
public class PersistentConnection extends HttpServlet
{
public void doGet(HttpServletRequest req,
HttpServletResponse resp)
throws ServletException, IOException
{
resp.setBufferSize(32 * 1024);
resp.setContentType("text/html");
PrintWriter out = resp.getWriter();
// Generate a response
}
}

22. Status Codes
• Status code constants
• sendError method used to set status code

23. Multimedia Content
• Returning a file
• Dynamically generating images

24. Summary
 Use client-side caching
 Use client pull to update a client
 Redirect the client to another URL
 Use persistent connections
 Use response status codes
 Return a file to a client
 Dynamically generate images

25. Copyright © 2002 ProsoftTraining. All rights reserved.
Lesson 4:
Servlet Sessions

26. Objectives
• Track a session using hidden form fields
• Track a session using URL rewriting
• Track a session using cookies

27. Hidden
Form Fields
<INPUT TYPE="HIDDEN" NAME="SID" VALUE="1234567890">
Hidden form field named "SID"
with an assigned value of
"1234567890"

28. URL
Rewriting
• Servlets can build URLS that add information
in the form of additional path information

29. Cookies
• Small pieces of information transmitted from a
Web server to a Web browser
• Represented in Java using the Cookie class

30. Summary
 Track a session using hidden form fields
 Track a session using URL rewriting
 Track a session using cookies

31. Copyright © 2002 ProsoftTraining. All rights reserved.
Lesson 5:
Authentication
and Security

32. Objectives
• Authenticate a user using HTTP-based
authentication
• Authenticate a user using a form
• Use Secure Sockets Layer to improve security

33. HTTP-Based
Authentication
• Users
• The deployment descriptor
• Servlets and authentication

34. Form
Authentication
• Requires modification of the deployment
descriptor
– The login-config element must be
modified to indicate that form
authentication is to be used and to provide
the URL for a login page and login error
page

35. Summary
 Authenticate a user using HTTP-based
authentication
 Authenticate a user using a form
 Use Secure Sockets Layer to improve security

36. Copyright © 2002 ProsoftTraining. All rights reserved.
Lesson 6:
Inter-Servlet
Communication

37. Objectives
• Share data with another servlet
• Handle a single request using multiple
servlets

38. Sharing Data
• Data-sharing methods of the
ServletContext interface
• Sharing data with another ServletContext

39. Dispatching
to Another Servlet
• The forward method
• The include method

40. Summary
 Share data with another servlet
 Handle a single request using multiple
servlets

41. Copyright © 2002 ProsoftTraining. All rights reserved.
Lesson 7:
Building Enterprise
Web Applications

42. Objectives
• Use JNDI to look up EJBs, resource factories
and environment entries
• Write servlets for use in a distributed
environment
• Use JavaMail to send e-mail

43. Java Servlets and JNDI
• Referencing EJBs
• Referencing resource factories
• Referencing environment entries

44. Clustering
and Java Servlets
• Clustering styles
• Developing distributable servlets

45. JavaMail
• Add-on API that creates a full-fledged
POP/iMAP client
– Session class
– getDefaultInstance static method

46. Summary
 Use JNDI to look up EJBs, resource factories
and environment entries
 Write servlets for use in a distributed
environment
 Use JavaMail to send e-mail

47. Copyright © 2002 ProsoftTraining. All rights reserved.
Lesson 8:
Internationalization

48. Objectives
• Use the Unicode escape sequence to specify
special Latin characters
• Use alternative character sets to generate a
non-Latin character response

49. The Latin
Character Set
• Non-English Latin characters
• Languages and language codes

50. Non-Latin
Character Sets
• Arabic
• Chinese
• Japanese
• Korean
• Russian

51. Summary
 Use the Unicode escape sequence to specify
special Latin characters
 Use alternative character sets to generate a
non-Latin character response

52. Java Servlets
 Introduction to Java Servlets
 The Servlet Life Cycle
 Responding to a Request
 Servlet Sessions
 Authentication and Security
 Inter-Servlet Communication
 Building Enterprise Web Applications
 Internationalization