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Exam Notes for the Sun Certified Web Component Developer (SCWCD) Exam

Section 10: Designing and Developing JSPs Using JavaBeans

10.1 For any of the following tag functions, match the correctly constructed tag, with attributes and values as appropriate, with the corresponding description of the tag's functionality:

• Declare the use of a JavaBean component within the page.

• Specify, for jsp:useBean or jsp:getProperty tags, the name of an attribute.

• Specify, for a jsp:useBean tag, the class of the attribute.

• Specify, for a jsp:useBean tag, the scope of the attribute.

• Access or mutate a property from a declared JavaBean.

• Specify, for a jsp:getProperty tag, the property of the attribute.

• Specify, for a jsp:setProperty tag, the property of the attribute to mutate, and the new value.

<jsp:useBean>

<jsp:useBean id=”connection”class=”com.myco.myapp.myBean” scope=”page” /> - create if bean doesn’t exist

<jsp:useBean id=”connection” beanName=”com.myco.myapp.myBean.ser” /> - create from a serialized object

<jsp:useBean id=”connection” type=”com.myco.myapp.myBean” /> - Bean should already exist

<jsp:useBean id="name" scope="page|request|session|application" typeSpec />

typeSpec ::=                 class=”className” |

class=”className” type=”typeName” |

type=”typeName” class=”className” |

beanName=”beanName” type=”typeName” |

type=”typeName” beanName=”beanName” |

type=”typeName”

• First the container looks for the specified bean in the specified scope (default scope is page), if it is not there, one will be created. With beanName, you can specify a serialized file for instantiating the bean from.

• class or beanName is required, type is optional.

• If class and beanName are not specified (only type is specified), the bean will not be created, it should already exist in the specified scope.

• The specified class should not be an abstract class or an interface and should have a public no-args constructor. If type is specified, the instantiated class is casted to the type. Instantiate method is used to create the bean.

• jsp:useBean action element can have a non-empty body, e.g. a jsp:setProperty action; the body will be executed for newly instantiated beans only

<jsp:useBean id="name" scope="page|request|session|application" typeSpec >

body – usually this will be scriptlets or jsp:setProperty actions

</jsp:useBean>

<jsp:getProperty>

<jsp:getProperty name=”beanName” property=”propName” />

<jsp:setProperty>

<jsp:setProperty name=”bean1” property=”*” /> 

-- all request parameters will be set in bean’s properties (with matching names)

<jsp:setProperty name=”bean2” property=”user ” param=”username ” />

                -- request parameter ‘username’ will be set to ‘user’ property of the bean

<jsp:setProperty name=”bean2” property=”user ”  />

-- request parameter ‘user’ will be set to ‘user’ property of the bean (since no param specified, it is assumed to have the same name as the property)

<jsp:setProperty name=”bean2” property=”user ”  value=”me” />

<jsp:setProperty name=”bean2” property=”user ” value=”<%=session.getAttribute(“user”) %>“ />

                -- new value can be specified with an expression. If it’s an expression no conversion is performed, else standard conversion is performed.

Note: value cannot be used in conjunction with param

10.2 Given JSP page attribute scopes: request, session, application, identify the equivalent servlet code.

request - HTTPServletRequest

session – HTTPServletRequest.getSession() : HTTPSession

application – GenericServlet.getServletContext() or GenericServlet.getServletConfig().getServletContext()

10.3 Identify techniques that access a declared JavaBean component.

A declared JavaBean can also be accessed using: (the name specified in the id attribute of <jsp:useBean>)

Scriptlets

Expressions

Custom Tags