CSC 485 IST 350

obsequiousravioliSoftware and s/w Development

Oct 29, 2013 (3 years and 7 months ago)

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CSC 485

IST 350


JSP

What Is JSP


JSP stands for JavaServer Page


Available since 1999 (JSP 1.0), and now in JSP 1.2


Part of the J2EE API:


considered as Web Components, together with Java Servlet


JavaServer Pages (JSP) technology provides a
simplified, fast way to create web pages that
display dynamically
-
generated content.


A Simple JSP Page


A JSP page is like a
regular

HTML page with
special

tags

<html>

<head>

<title>

Current Time

</title>

</head>

<body>

Current time is
<%= new java.util.Date() %>

</body>

<html>

How Is a JSP Processed?

Web Server Host















Host Machine File System


/servlet/JSPFile.jsp



Web Server



Servlet

Engine

JSP

Translator

Web Browser



Send a request

URL

HTML returned

Generate
response

Get

servlet

Get JSP

file

Request

servlet

Process

servlet

Sample URL

http://www.server.com:8080/servlet/JSPFile

How Does JSP Work?
(older view)


A client requests a JSP page from a web server


The web server must support JSP (such as the
Tomcat server)


The JSP pages must have a .jsp extension


The web server


Translates the JSP into a Java servlet


Compiles the servlet, and


Executes it


The result of the execution, an HTML page, will
be sent back to the browser

How Does JSP Work?
(current view)


JSP pages use XML tags and scriptlets written in the
Java programming language to encapsulate the logic
that generates the content for the page.


It passes any formatting (HTML or XML) tags directly
back to the response page. In this way, JSP pages
separate the page logic from its design and display.


JSP technology is part of the Java technology family.
JSP pages are compiled into servlets and may call
JavaBeans components (beans) or Enterprise
JavaBeans components (enterprise beans) to perform
processing on the server.


JSP Constructs


Scripting constructs


Expressions:
<%=
java
-
expr

%>


Scriptlets:
<%
java
-
statement(s);

%>


Declarations:

<%
java method or field declaration

%>


Comments:
<%
--

JSP comment

--
%>


<!
--

HTML comment

--
>


Directives:
<%@
directive attr1=“value1”



[attr2=“value2”]

%>


Actions

Using JavaBeans in JSP


A JavaBeans component may be used in a JSP
to provide information needed in generating
dynamic contents


A class is a JavaBeans component if


The class is public


The class has an no
-
args public constructor


The class is serializable


The syntax is


<jsp:useBean id=“
objName
” scope=“
...



class=“
ClassName
” />

Getting and Setting Properties


The JavaBeans components normally have
getters and setters


These methods can be used as follows


Passing information into the page


<jsp:getProperty id=“
beanId
” property=“
sample



/>


Retrieving information from the page

<jsp:setProperty id=“
beanId
” property=“
sample

value=“test1”/>


Typically, these constructs will be missed up
with HTML tags