Bài Giảng Lập Trình JSP P15 End
Bài Giảng Lập Trình JSP _P15 End
... to general response page
}
Using Request Properties
•
Example: Sending custom image types
–
Send .png image if supported
–
Send .jpg image otherwise
String imagetypes = request.getHeader(“Accept”);
boolean ... display response as Excel spreadsheet
–
response.setContentType(“application/vnd.ms-excel”);
–
Send response back in simple format:
•
Cells in same row separated by tab ‘\t’
•
Move t...
Bài Giảng Lập Trình JSP _P1
... information
2
Client-Server Web Architecture
•
Client browser sends request for page to server
–
May contain form data and other information
•
Server sends response page and sends to client
•
May need to generate response ... statements
–
Connection pooling
web container
control
servlet
JSP
database
database
driver
JDBC
DBMS
database server
11
User-friendly Error Handling
•
Tell user what...
Bài Giảng Lập Trình JSP _P2
... Syllabus</title></head><body>…)
•
Client browser sends request for page to server
•
Server sends response page and sends to client
... site
Structure shown
in the project
window
Creates an
initial index .jsp
page (default
home page of
the new site)
The index .jsp is initially just a
“Hello world” page
Building a Web Application
Tomcat ... it in a directory called 6...
Bài Giảng Lập Trình JSP _P3
... library
22
Commenting JSP Files
•
Crucial to future maintenance of site
•
Inside of JSP code (between <% and %>):
// comment
/* comment */
•
Outside of JSP code (that is, in html)
<! comment >
8
JSP ... 10
JSP Scoping
•
Variable declared in a
block of JSP on a page
•
May be accessed by
any other JSP on same
page
•
No access to variable
from any ...
middle)
17
Ha...
Bài Giảng Lập Trình JSP _P4
... MULTIPLE>
•
Sends name=value string for each option
selected
…peripherals=camera&peripherals=scanner…
•
getParameter method will not work!
7
Example Result
9
Checkbox JSP
•
If execute JSP code:
String ... monitor is checked
–
No mention of monitor if not checked
10
Conditions in Java
•
JSP may need to do different things
depending on checkbox
–
Display “Monitor” if checked
–
Di...
Bài Giảng Lập Trình JSP _P5
... etc.).
–
Decide which JSP should be sent back as response.
–
Forward control (and request data) to that JSP.
request
Control
servlet
JSP
response
JSPs act
as views
JSP
JSP
Servlet Details
•
Important ... JSP)
–
Methods invoked by a request for the servlet
–
Usually redirects to a JSP
Tomcat
Request for servlet
Servlet
Servlet methods called
JSP
Redirect to
appropriate
respo...
Bài Giảng Lập Trình JSP _P6
... context.getInitParameter(“name");
•
Accessing from a JSP:
–
String value = application.getInitParameter(“name");
Built-in object in JSP
(like “request”)
Context Parameters
Form of xml tag
Welcome ... Parameters
Form of xml tag
Welcome Page Properties
•
Page shown at webapp startup
–
Default: index .jsp
•
Can change to a new welcome file
Configuration Files
•
Each webapp has a...
Bài Giảng Lập Trình JSP _P7
... Messages in JSP
Calendar Dates in Java
•
Construct a new GregorianCalendar object
–
Contains information about current date when created
–
Must import java.util.* library
•
Use get(Calendar.fieldname) ... approach:
Force JSP to repeat validation done in servlet to determine which
messages to display
•
Better approach:
Once servlet detects error, it creates error message and passes to...
Bài Giảng Lập Trình JSP _P8
... other JSPs test whether attribute is null
•
If so, redirect to another page
–
Initial page in sequence
–
Error page telling session has expired
•
Syntax for redirection from JSP:
< ;jsp: forward ... Data
•
Servlets/JSPs can store data associated with session ID
•
Servlets/JSPs can look up that data in future when
passed the session ID in request
Server
session ID Client data
Servlet or...
Bài Giảng Lập Trình JSP _P9
... list
Used together to
loop through and
show all Items on
“shopping cart” page
Getting Cost in JSP
Order Class
Business Model Objects
Key idea:
•
Methods in model objects should implement
business ... set/get quantity
–
Method to get total cost of order
•
Computed from quantity here instead of in JSP/ servlet
–
Method to check whether quantity valid in terms of
business model
•
Servlet...