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13.1 Basic Bean Use

attributes:

name

 (which should match the

id

 given by

jsp:useBean

),

prop

erty

 (the name of the property to change), and

value

 (the new value). Sec

tion 13.3 (Setting Bean Properties) discusses some alternate forms of

jsp:setProperty

 that let you automatically associate a property with a

request parameter. That section also explains how to supply values that are

computed at request time (rather than fixed strings) and discusses the type

conversion conventions that let you supply string values for parameters that

expect numbers, characters, or boolean values.

An alternative to using the

jsp:setProperty

 action is to use a scriptlet

that explicitly calls methods on the bean object. For example, given the

book1

 object shown earlier in this section, you could use either of the follow

ing two forms to modify the

title

 property:

property="title"

value="Core Servlets and JavaServer Pages" />

<% book1.setTitle("Core Servlets and JavaServer Pages"); %>

Using

jsp:setProperty

 has the advantage that it is more accessible to

the nonprogrammer, but direct access to the object lets you perform more

complex operations such as setting the value conditionally or calling methods

other than

getXxx

or

setXxx

 on the object.

Installing Bean Classes

The class specified for the bean must be in the server's regular class path, not

the part reserved for classes that get automatically reloaded when they

change. For example, in the Java Web Server, the main bean class and all the

auxiliary classes it uses should go in the

install_dir/classes

 directory or

be in a JAR file in

install_dir/lib

, not in

install_dir/servlets

. Since

Tomcat and the JSWDK don't support auto reloading servlets, bean classes

can be installed in any of the normal servlet directories. For Tomcat 3.0,

assuming you haven't defined your own Web application, the primary direc

tory for servlet class files is

install_dir/webpages/WEB INF/classes

; for

the JSWDK, the default location is

install_dir/webpages/WEB INF/servlets

. With all three servers,

remember that a package name corresponds to a subdirectory. So, for exam

ple, a bean called

Fordhook

 that declares

package lima;

  would typically

be installed in the following locations:

Tomcat 3.0:

install_dir/webpages/WEB INF/classes/lima/Fordhook.cla

ss

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

Servlet and JSP training courses by book's author: courses.coreservlets.com.

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