1. CS520 Web Programming Bits and Pieces of Web Programming (II)
Chengyu Sun
California State University, Los Angeles

2. Roadmap File upload and download Sending email
Task scheduling and execution
Application deployment

3. File Upload – The Form <form action="FileUploadHandler"
method="post"
enctype="multipart/form-data">
First file: <input type="file" name="file1" /> <br />
Second file: <input type="file" name="file2" /> <br />
<input type="submit" name="upload" value="Upload" />
</form>

4. File Upload – The Request
POST / HTTP/1.1
Host: cs.calstatela.edu:4040
[…]
Cookie: SITESERVER=ID=289f7e a2d7d1e6e44f931195
Content-Type: multipart/form-data; boundary=
Content-Length: 509
Content-Disposition: form-data; name="file1"; filename="test.txt"
Content-Type: text/plain
this is a test file.
Content-Disposition: form-data; name="file2"; filename="test2.txt.gz"
Content-Type: application/x-gzip
?????????UC

5. Apache commons-fileupload
Maven dependency:
commons-fileupload:commons-fileupload
FileItemFactory fileItemFactory = DiskFileItemFactory();
ServletFileUpload fileUpload = new ServletFileUpload( fileItemFactory );
List items = fileUpload.parseRequest( request );
for( Object o : items ) {
FileItem item = (FileItem) items;
if( ! item.isFormFiled() ) {...} }

6. Handle File Upload in Spring
multipartResolver bean
Support multiple request parser libraries
See CSNS2 for example
Add argument of type MultipartFile to the controller method

7. Store Uploaded Files In database On disk Pros and Cons?? BLOB, CLOB
BINARY VARCAR, VARCHAR
On disk
Pros and Cons??

8. File Download Generate an HTTP response directly Understand Java IO
Add an HttpServletResponse argument to the controller method
Return null for view
Understand Java IO
Reader and Writer
InputStream and OutputStream
Use of the Content-Disposition header

9. How Email Works SMTP, IMAP, POP Email Server A Email Server B ?? ?? ??
Client A
Client B

10. JavaMail http://www.oracle.com/technetwork/java/javamail/index.html
Maven dependency: javax.mail:mail
Properties props = System.getProperties();
props.put("mail.smtp.host", mailhost);
Session session = Session.getInstance( props );
Message msg = new MimeMessage(session);
...
Transport.send( msg );

11. Spring Email Support Mail message classes
Need spring-context-support dependency
Declare a mailSender bean
JavaMailSender interface
See CSNS2 for example
Mail message classes
Simpl Message
No attachment, no special character encoding
Mim Message

12. Set Up a Local Email Server for Testing
hMailServer on Windows -
postfix on Linux -

13. Examples of Scheduled Tasks
Periodic notifications
Weekly sales
Member interests
Payment reminders
Batch data processing

14. Concepts in Task Scheduling and Execution …
Executor
Use one thread for each task
Use one thread for all tasks
Use a thread pool
Schedule (a.k.a. Trigger)
E.g. every 5 minutes, every day at midnight, every first Sunday of each month at 8am …

15. … Concepts in Task Scheduling and Execution
Scheduler
Task
Schedule/Trigger
Executor

16. Spring Configuration <task> namespace
<task:scheduler id="scheduler" />
<task:executor id="executor"
pool-size="5"/>
<task:annotation-driven
scheduler="scheduler"
executor="executor" />
Creates a scheduler
Creates a thread pool
Based executor
Enables annotations
@Scheduled and
@Async

17. @Scheduled

18. Cron Expression Six field separated by space Seconds (0-59)
Minutes (0-59)
Hours (0-23)
Day of month (1-31)
Month (1-12 or JAN-DEC)
Day of week (1-7 or MON-SUN)

19. Cron Field Values Single value, e.g. 12 Set of values, e.g. 0,15,30,45
Range, e.g. 1-12,MON-FRI,* (first-last)
Range with step, e.g. 1-12/3

20. Cron Expression Examples
Every hour at the beginning
of the hour
0 0 * * * *
0 */10 * * * *
0 0 8 * * MON-FRI
,15 * *
Every 10 minutes
Every weekday at 8AM
Every 1st and 15th of each
month at 1AM

21. Application Deployment
Deploy Application
Computer for
Development
Server Hosting the
Web Application

22. Directory Structure of a Java Web Application
Application Root Directory
JSPs and static resources
WEB-INF
web.xml
classes
Compiled Java classes
lib
Additional Java libraries

23. WAR Files Web application ARchive
A JAR file for packaging, distributing, and deploying Java web applications
Create WAR files
The command line tool jar
Eclipse Export -> Web -> WAR file
mvn package

24. Deploy WAR Files to a Tomcat Server
Copy the WAR file to the webapps folder
Use the Manager App
Need a user with the manager-gui role
More options at