Bài Giảng Lập Trình JSP P2
Bài Giảng Lập Trình JSP _P1
... database
•
Efficiency issues
–
Prepared statements
–
Connection pooling
web container
control
servlet
JSP
database
database
driver
JDBC
DBMS
database server
11
User-friendly Error Handling
•
Tell user
Bài Giảng Lập Trình JSP _P2
... Building a Web Application
•
Modify and add files to create web site
index .jsp
Prompts user for
number of widgets
reciept .jsp
Displays number of
widgets purchased
Deploying your Site to Tomcat
•
Right-click ... 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
B...
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 ... code
Data from...
Bài Giảng Lập Trình JSP _P4
...
selected
…peripherals=camera&peripherals=scanner…
•
getParameter method will not work!
7
Example Result
9
Checkbox JSP
•
If execute JSP code:
String monitor =
request.getParameter("monitor");
monitor will have ... VALUE="Printer“/>Printer
<OPTION VALUE="Scanner“/>Scanner
</SELECT>
23
JSP for Multiple Selection Lists
•
String[] request.getParam...
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
... 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
JSP as attribute
Servlet
Detects ... type=“text” name=“fieldname”
value= “<%= fieldValue %>” >
Displaying Error Messages in JSP
Calendar Dates in Java
•
Construct a new GregorianCalendar object...
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...
