Virtual Classroom

1
Virtual Classroom

• HongBing Kou , Jun Xu , Hu Li
• May, 2001

2
Project Overview

• Login
• Teachers role
• Post materials
• Add quiz
• Record Video
• Play Video
• Students role
• Read materials
• Take quiz
• Watch Video Materials

3
Register
login
Student
Teacher
Read Materials
Take Quiz
Watch Video
Upload Materials
Add Quiz
Record Video
Watch Video
4
Instant DB
Login Servlet
login
Postquiz servlet
Student
addquiz.jsp
Teacher
quiz.xml
quiz.jsp
filelist.jsp
Record applet
Player applet
Video Media
5
Login Part

• Inner tier
• LoginManager
• addUser
• userExists
• changeUserLevel
• changePasswords
• UserItem
• Middle layer Servlet
• Login
• Register
• Interface Html
• Teachers main page
• Studentss main page

6
DB InstantDB

• private Connection con
• private Statement stmt
• String url "jdbcidbC//tomcat//webapps//Fina
  l//sample.prp"
• String driver "org.enhydra.instantdb.jdbc.idbD
  river"
• Class.forName(driver)
• con DriverManager.getConnection(url)

7
User Structure UserItem class

• public class UserItem
• private String username
• private String password
• private int accessLevel
• public UserItem(String username, String
  password)
• this.username username
• this.password password
• this.accessLevel 0

8
Quiz Part

• Teacher
• Create quiz.xml
• Use addquiz servlet to get quiz from webpage

9
toFile.println("ltquestiongt") String
title req.getParameter("title") String
answer1 req.getParameter("a1") String
answer2 req.getParameter("a2") String
answer3 req.getParameter("a3") String
answer4 req.getParameter("a4")
String solution req.getParameter("solution")
toFile.println("lttitlegt" title
"lt/titlegt\n") toFile.println("ltanswer1gt"
answer1 "lt/answer1gt\n") toFile.println(
"ltanswer2gt" answer2 "lt/answer2gt\n") toF
ile.println("ltanswer3gt" answer3
"lt/answer3gt\n") toFile.println("ltanswer4gt"
answer4 "lt/answer4gt\n") toFile.println
("ltsolutiongt" solution "lt/solutiongt\n")
toFile.println("lt/question
gt")
10

• Student
• Take a quiz
• Using jsp file to show xml file
• Parse the quiz.xml and save it into DOM tree,
  show the tree on webpage
• submit the quiz result and report score

11
//Read XML file //try //Open the file for
reading URL u new URL(fileName) InputStrea
m inputXML u.openStream() //Build
document DocumentBuilder builder
factory.newDocumentBuilder() document
builder.parse(inputXML) //Generate the
NodeList org.w3c.dom.NodeList nodeList_q
document.getElementsByTagName("title") listLeng
th nodeList_q.getLength() org.w3c.dom.NodeLis
t nodeList_a1 document.getElementsByTagName("ans
wer1") org.w3c.dom.NodeList nodeList_a2
document.getElementsByTagName("answer2")
org.w3c.dom.NodeList nodeList_a3
document.getElementsByTagName("answer3")
org.w3c.dom.NodeList nodeList_a4
document.getElementsByTagName("answer4")
//Exception Handling //catch(Exception
e) // // msg msg e.toString() //
12
lt String parameterValue "" , radioName ""
for(int i 1 i lt nodeList_s.getLength(
) 1 i) radioName "A" i
parameterValue
request.getParameter(radioName)
org.w3c.dom.Node node nodeList_s.item(i-1)
nodeValue (String)node.getFirstChild(
).getNodeValue() //solution gt
ltTRgt ltTDgtltigt.Your
answerltparameterValuegt lt if(
parameterValue.compareTo(nodeValue) 0) gt
ltimg src"tick.gif" width"12"
height"12"gt lt else gt
ltimg src"del.gif" width"12"
height"12"gt lt gt
lt/TDgt lt/TRgt ltTRgt
ltTDgtCorrect answerltnodeValuegtlt/TDgt
lt/TRgt lt gt
13
Player

• Function
• Automatically pick up the Video/Audio Materials
  by Java Bean
• Dynamically create the links to play Video/Audio
  by JSP
• Player created by JMF 1.0 in Applet type

14
Java Bean JSP

• A Bean was created to pick up all files in the
  folder. Also provide method to get file info. Ex
  created date , size etc
• Dynamically create the user page for selecting
  the Media file

15
Structure JMF API

• System Structure

• Event based Media player by JMF 2.1.1

16
Camcorder

• Function
• A user friendly camcorder developed by with
  JMF2.1
• Record and save the Video/Audio/Other media
  streams as a media file ( Because of Java policy
  cant work well in the browser)
• Monitor the record process

17
Record workflow

• Create the DataSink and Process from the given
  Capture Device. Usually its VFW//0 for video or
  javasound//0 for Audio
• GetoutputSource from the Processor.
• Create the DataSink to write file
• Start the processor and the DataSink
• Block until finish recording work

18
Problems with my Camcorder

• Cant work well in the Applet
• Record the Video Audio at the same time ? (
  Realized processor ? A solution or Merge
  technology)