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Using JavaBean Classes
Part:
1
2
3
4
5
(Continued from previous part...)
Note that:
- Property names are case sensitive. Property name "Author" can not be mapped to
"getAuthor" method.
- Two set methods without any one taking String as input parameter type is giving
me problem to set "total".
- Two set methods with one taking String as input parameter type is ok. Output
line 5 is the prove.
Using JavaBeans as Objects in Scripting Elements
As I mentioned in the previous section, JavaBean is just a normal Java object with
some special method. Once a JavaBean is created, we should be able to use it as
Java object in any scripting elements.
Here is a sample page to show you how to use a JavaBean as a Java object. It is using
the same JavaBean class, herong.DemoBean, as the previous section.
<?xml version="1.0"?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="1.2">
<!-- BeanAsObject.jsp
Copyright (c) 2003 by Dr. Herong Yang
-->
<html><body>
<jsp:useBean id="b" class="herong.DemoBean"/>
<jsp:setProperty name="b" property="author" value="Someone"/>
Line 11: author =
<jsp:expression>b.getAuthor()</jsp:expression><br/>
<jsp:scriptlet><![CDATA[b.setTotal(10);]]></jsp:scriptlet>
Line 12: total =
<jsp:getProperty name="b" property="total"/><br/>
<jsp:scriptlet><![CDATA[b.setSize(15);]]></jsp:scriptlet>
Line 13: size =
<jsp:getProperty name="b" property="size"/><br/>
Line 14: size =
<jsp:scriptlet><![CDATA[out.println(b.getSize());]]></jsp:scriptlet>
<br/>
<jsp:scriptlet><![CDATA[
Object o = pageContext.findAttribute("b");
String s = ((herong.DemoBean)o).getSize();
out.println("Line 15: size = "+s);
]]></jsp:scriptlet><br/>
</body></html>
</jsp:root>
Open this JSP page with IE, you will get:
Line 11: author = Someone
Line 12: total = int: 10
Line 13: size = int: 15
Line 14: size = int: 15
Line 15: size = int: 15
Note that:
- Line 11 tells us that we can use an expression element to get the property value.
- Line 12 tells us that if we use scriptlet element, we can call a specific
version of setTotal method. Remember setProperty failed on "total" in the previous
example.
- Line 15 tells us that we also retrieve the object back from pageContext, because
useBean element store the JavaBean object in pageContext.
(Continued on next part...)
Part:
1
2
3
4
5
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