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13.3 Setting Bean Properties

Figure 13 1 Result of StringBean.jsp.

13.3 Setting Bean Properties

You normally use

jsp:setProperty

 to set bean properties. The simplest

form of this action takes three attributes:

name

 (which should match the

id

given by

jsp:useBean

),

property

 (the name of the property to change), and

value

 (the new value).

For example, the

SaleEntry

 class shown in Listing 13.3 has an

itemID

property (a

String

), a

numItems

 property (an

int

), a

discountCode

 prop

erty (a

double

), and two read only properties

itemCost

and

totalCost

(each of type

double

). Listing 13.4 shows a JSP file that builds an instance of

the

SaleEntry

 class by means of:

The results are shown in Figure 13 2.

Once the bean is instantiated, using an input parameter to set the

itemID

is straightforward, as shown below:

    name="entry"

    property="itemID"

    value= <%= request.getParameter("itemID") %>  />

Notice that I used a JSP expression for the

value

 parameter. Most JSP

attribute values have to be fixed strings, but the

value

and

name

 attributes of

jsp:setProperty

 are permitted to be request time expressions. If the

expression uses double quotes internally, recall that single quotes can be used

instead of double quotes around attribute values and that

\'

and

\"

 can be

used to represent single or double quotes within an attribute value.

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