The <

jsp:setProperty>

 element has the following attributes:

name

The name of a Bean instance defined by a 

 element or 

some other element. The Bean instance must contain the property you 

want to set. The defining

element (in JSP 1.1 only a 

element) must appear before the 

 element in the 

same file.

property

The name of the Bean property whose value you want to set

If you set 

propertyName

 to 

*

 then the tag will iterate over the 

current 

ServletRequest

 parameters, matching parameter names 

and value type(s) to property names and setter method type(s), setting 

each matched property to the value of the matching parameter. If a 

parameter has a value of   , the corresponding property is not 

modified.

param

The name of the request parameter whose value you want to give to a 

Bean property. The name of the request parameter usually comes from a 

Web form

If you omit 

param

, the request parameter name is assumed to be the 

same as the Bean property name

If the param is not set in the Request object, or if it has the value of   , 

the 

jsp:setProperty

 element has no effect (a noop).

An action may not have both 

param

 and 

value

 attributes.

value

The value to assign to the given property.

This attribute can accept a request time attribute expression as a value.

An action may not have both 

param

 and 

value

 attributes.

2.13.3

An 

 action places the value of a Bean instance property, converted to 

a 

String

, into the implicit 

out

 object, from which you can display the value as output. The 

Bean instance must be defined as indicated in the 

name

 attribute before this point in the page 

(usually via a 

useBean

 action).

The conversion to String is done as in the println() methods, i.e. the 

toString()

 method 

of the object is used for Object instances, and the primitive types are converted directly.

If the object is not found, a request time exception is raised.

Chapter 2

Standard Syntax and Semantics

66