Core Servlets and JavaServer Pages™

A.13. Using JavaBeans with JSP

Basic Requirements for Class to be a Bean

1. Have a zero-argument (empty) constructor.

2. Have no public instance variables (fields).

3. Access persistent values through methods called getXxx (or isXxx) and setXxx.

Basic Bean Use

• <jsp:useBean id="name" class="package.Class" />

• <jsp:getProperty name="name" property="property" />

• <jsp:setProperty name="name" property="property"
                   value="value" />
  

The value attribute can take a JSP expression.

Associating Properties with Request Parameters

• Individual properties:

  <jsp:setProperty
      name="entry"
      property="numItems"
      param="numItems" />
  

• Automatic type conversion: for primitive types, performed according to valueOf method of wrapper class.

• All properties:

   <jsp:setPropert y name="entry" ...