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13.3 Setting Bean Properties

Associating Individual Properties with Input

Parameters

Setting the

itemID

 property was easy since its value is a

String

. Setting the

numItems

and

discountCode

 properties is a bit more problematic since

their values must be numbers and

getParameter

 returns a

String

. Here is

the somewhat cumbersome code required to set

numItems

<%

int numItemsOrdered = 1;

try {

  numItemsOrdered =

    Integer.parseInt(request.getParameter("numItems"));

} catch(NumberFormatException nfe) {}

%>

    name="entry"

    property="numItems"

    value="<%= numItemsOrdered %>" />

Fortunately, JSP has a nice solution to this problem that lets you associate

a property with a request parameter and that automatically performs type

conversion from strings to numbers, characters, and boolean values. Instead

of using the

value

 attribute, you use

param

 to name an input parameter. The

value of this parameter is automatically used as the value of the property, and

simple type conversions are performed automatically. If the specified input

parameter is missing from the request, no action is taken (the system does

not pass

null

 to the associated property). So, for example, setting the

numItems

 property can be simplified to:

Figure 13 2 Result of SaleEntry1.jsp.

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