Client Components

All the JavaBeans components used in the web client are instantiated by the managed bean facility (see Configuring a Bean) when they are encountered in the page, such as when an EL expression references the component. The managed bean facility is configured in the faces-config.xml file. The following managed-bean elements from the faces-config.xml file specify how AccountHistoryBean and CustomerBean are to be instantiated and stored in scope:

<managed-bean>
    <managed-bean-name>accountHistoryBean</managed-bean-name>
    <managed-bean-class>
        com.sun.tutorial.javaee.dukesbank.web.AccountHistoryBean
    </managed-bean-class>
    <managed-bean-scope>request</managed-bean-scope>
    ...
    <managed-property>
        <property-name>accountId</property-name>
        <value>#{param.accountId}</value>
    </managed-property>
    <managed-property>
    ...
</managed-bean>
<managed-bean>
    <managed-bean-name>customerBean</managed-bean-name>
    <managed-bean-class>
        com.sun.tutorial.javaee.dukesbank.web.CustomerBean
    </managed-bean-class>
    <managed-bean-scope>session</managed-bean-scope>
</managed-bean>

As shown by the preceding configurations, an AccountHistoryBean instance is saved into request scope under the name accountHistoryBean, and a CustomerBean instance is saved into session scope under the name customerBean. EL expressions use these names to reference the beans from a page. The managed bean configurations can also initialize bean properties with values. As shown in the preceding configuration, the accountId property of AccountHistoryBean is set to the expression #{param.accountId} when an instance of AccountHistoryBean is created. This expression references the accountId variable in the request parameter map. This is so that other pages in the application can pass the account ID to AccountHistoryBean and therefore make it available to the accountHist.jsp page.

Responsibility for managing the enterprise beans used by the web client rests with CustomerBean. It creates account and transaction controller enterprise beans and provides methods for retrieving the beans.

When instantiated, the CustomerBean component uses @EJB annotations to inject references to the enterprise beans. Because these enterprise beans apply to a particular customer or session, CustomerBean is stored in session.

public class CustomerBean {
        
        @EJB
        private AccountController accountController;

        @EJB
        private TxController txController;
        ...
}

CustomerBean also does the following:

• Maintains the customer ID

• Retrieves the list of accounts from the database

• Gets detailed information about a particular account

• Invalidates a session to allow a customer to log out.

Because CustomerBean is in session, it is a convenient place to keep account information so that the backing beans and their associated pages can pass this information between themselves.

The page fragment template/links.jsp generates the list of bank function links at the top of every page. Notice that the customer is retrieved from the userPrincipal object, which is set when the customer logs in (see Protecting the Web Client Resources). After the customer is set, the page can retrieve the collection of accounts from CustomerBean.

As shown by the following code from links.jsp, the ID of the first account in the collection of accounts is set into request scope. The setPropertyActionListener tag is nested inside the commandLink tag, which represents the hyperlink that launches the atm.jsp page. This setPropertyActionListener tag causes the account ID to be set in request scope when the hyperlink is clicked.

...
    <c:set var="accountId" scope="request"
             value="${customerBean.accounts[0].accountId}"/>
    <h:commandLink value="#{bundle.ATM}" action="atm">
        <f:setPropertyActionListener
                 target="#{requestScope.accountId}"
                 value="#{customerBean.accounts[0].accountId}"/>
    </h:commandLink>
...