Creating the Web Client (Your First Cup: An Introduction to the Java EE Platform)

Your First Cup: An Introduction to the Java EE Platform

Creating the Web Client

To create the web client, you need to perform the following tasks:

Create a resource bundle to hold localized messages used by the Facelets pages.
Configure the resource bundle in the configuration file.
Create the DukesBDay managed bean class.
Create the Facelets pages.

Creating a Resource Bundle

In this section, we'll create the resource bundle that contains the static text and error messages used by the Facelets pages. The firstcup client supports both English and Spanish locales. Therefore we need to create two properties files, each of which will contain the messages for one of the locales.

Creating a Resource Bundle

Right-click firstcup in the Projects pane.

Select New -> Other from the popup menu.

Select the Other category, then Properties File from the New File dialog and click Next.

In the New Properties File dialog, enter WebMessages in the File Name field.

In the Folder field, enter src/java/firstcup/web as the location of the file.

Click Finish.

After NetBeans IDE creates the properties file, enter the following messages or copy them from here to the file:

Welcome=Hi. My name is Duke. Let us find out who is older -- You or me. 
DukeIs=Duke is
YearsOldToday=years old today.
Instructions=Enter your birthday and click submit.
YourBD=Your birthday
Pattern=MM/dd/yyyy
DateError=Please enter the date in the form MM/dd/yyyy.
YouAre=You are 
Year=year
Years=years
Older=older than Duke!
Younger=younger than Duke!
SameAge= the same age as Duke!
Submit=Submit
Back=Back
AverageAge=The average age difference of all First Cup users is

These messages will be referenced from the XHTML pages.

Save the file by selecting File -> Save from the menu.

To add the Spanish translations of the messages, copy the properties file WebMessages_es.properties from tut-install/firstcup/example/firstcup/src/java/com/sun/firstcup/web to tut-install/firstcup/myexample/firstcup/src/java/firstcup/web.

You can create multiple properties files, each with a set of messages for a different locale. By storing localized static text and messages in resource bundles, you don't need to create a separate set of XHTML pages for each locale.

Configuring the Resource Bundle in the Configuration File

To make the resource bundle available to the application, you need to configure it in the configuration file, by performing the following task.

Creating a Configuration File

The faces-config.xml deployment descriptor contains configuration settings for the JavaServer Faces application. JSF applications don't require a deployment descriptor unless they use features that can only be configured in faces-config.xml. In firstcup, the deployment descriptor has settings defining the resource bundle that provides localized strings in English and Spanish.

Select firstcup in the Projects Pane and select File -> New File.

In the New File dialog, select JavaServer Faces under Categories, new JavaServer Face Configuration under File Types, click Next, then Finish.

Configuring the Resource Bundle

The firstcup application is localized for English and Spanish languages. JavaServer Faces applications can automatically select the proper language based on the locale of the user's web browser. Specify the default and supported locales in the faces-config.xml file.

With the newly created faces-config.xml file open, click XML.

Add the following <application> tag to configure the resource bundle:

<application>
	<resource-bundle>
		<base-name>firstcup.web.WebMessages</base-name>
		<var>bundle</var>
	</resource-bundle>
	<locale-config>
		<default-locale>en</default-locale>
		<supported-locale>es</supported-locale>
	</locale-config>
</application>

The base-name element of the resource-bundle element identifies the fully-qualified class name of the resource bundle. The var element identifies the name by which the XHTML pages will reference the resource bundle. The locale-config element identifies the locales supported by the resource bundle.

Right-click in the editor window and select Format.

Select File -> Save.

Creating the `DukesBDay` Managed Bean Class

The DukesBDay JavaBeans component is a backing bean. A backing bean is a JavaServer Faces managed bean that acts as a temporary data storage for the values of the components included on a particular JavaServer Faces page. A managed bean is a JavaBeans component that a JavaServer Faces application instantiates and stores in scope. The section following this one describes more about managed beans and how to configure them.

This section describes how to create the DukesBDay class. To create the class you need to do the following:

Create the managed bean class.
Add a property that stores Duke's current age from the JAX-RS web service.
Add a property that stores the user's current birth date.
Add a property that stores the age difference from the DukesBirthdayBean enterprise bean.
Add a property that stores the absolute value of the age difference.
Add a property that stores the average age difference of all users.
Add a method that calls DukesBirthdaybean.getAgeDifference, sets the absolute age difference, and forwards the user to the display page.

Creating the Managed Bean Class.

Create a JavaServer Faces managed bean class that will subsequently be modified.

Right-click the firstcup.web package in the Projects pane.

Select New -> Other.

Select JavaServer Faces under Categories, then JSF Managed Bean under File Types.

Enter DukesBDay in the Class Name field.

Select firstcup.web in the Package field.

Select session under Scope.

Click Finish.

Adding an Enterprise Bean Reference

Add a javax.ejb.EJB annotation to inject a reference to the DukesBirthdayBean enterprise bean. This session bean will be called from the methods in DukesBDay.

Right-click in the editor window and select Call Enterprise Bean.

In the Call Enterprise Bean dialog expand the firstcup application, select DukesBirthdayBean, and click OK. The following field will be added:
@EJB private DukesBirthdayBean dukesBirthdayBean;

Adding Properties to the Bean

During this task, you will add the following properties to the DukesBDay bean:

age for getting Duke's age from the web service.
yourBD to hold the user's birth date.
ageDiff to get the age difference from the enterprise bean.
absAgeDiff to hold the absolute value of the age difference.

Right-click in the Editor window, select Insert Code, then Add Property.

Enter age under Name, and set the Type to int, click OK.

Repeat the above steps to create the following properties: yourBD of type java.util.Date, ageDiff of type int, absAgeDiff of type int, and averageAgeDifference of type Double.

After the newly created property fields, add the following Logger instance:

private static Logger logger = Logger.getLogger("firstcup.web.DukesBDay");

Initialize the variables in the default constructor:

public DukesBDay() {
	age = -1;
	yourBD = null;
	ageDiff = -1;
	absAgeDiff = -1;
}

Right-click in the editor and select Format.

Right-click in the editor and select Fix Imports.

Select java.util.logging.Logger for the Logger class, and click OK.

Getting Duke's Current Age

While performing this task, you will add some code to the getAge method to access Duke's current age from the JAX-RS web service.

Use the java.net and java.io classes to create an HTTP connection to the Duke's Age web service and read in the result.

Add the following code to the getAge method.

public int getAge() {
    // Use the java.net.* APIs to access the Duke's Age RESTful web service
    HttpURLConnection connection = null;
    BufferedReader rd = null;
    StringBuilder sb = null;
    String line = null;
    URL serverAddress = null;

    try {
        serverAddress = new URL(
				"http://localhost:8080/DukesAgeService/resources/dukesAge");
        connection = (HttpURLConnection) serverAddress.openConnection();
        connection.setRequestMethod("GET");
        connection.setDoOutput(true);
        connection.setReadTimeout(10000);

        // Make the connection to Duke's Age
        connection.connect();

        // Read in the response
        rd = new BufferedReader(
				new InputStreamReader(connection.getInputStream()));
        sb = new StringBuilder();
        while ((line = rd.readLine()) != null) {
            sb.append(line);
        }

        // Convert the response to an int
        age = Integer.parseInt(sb.toString());
    } catch (MalformedURLException e) {
        logger.warning("A MalformedURLException occurred.");
        e.printStackTrace();
    } catch (ProtocolException e) {
        logger.warning("A ProtocolException occurred.");
        e.printStackTrace();
    } catch (IOException e) {
        logger.warning("An IOException occurred");
        e.printStackTrace();
    }

	return age;
}

Right-click in the editor window and select Format.

Right-click in the editor window and select Fix Imports.

Click OK.

Getting the Age Difference From the `DukesBirthdayBean` Enterprise Bean

During this task, you will create a processBirthday method to get the difference in age between the user's age and Duke's age from the EJB, set the absAgeDiff variable to the absolute value of the age difference, and set a result string that is will forward the user to the display page..

Add a processBirthday method with the following code:
```
    public String processBirthday() {
        this.setAgeDiff(dukesBirthday.getAgeDifference(yourBD));
        logger.info("age diff from dukesbday " + ageDiff);
        this.setAbsAgeDiff(Math.abs(this.getAgeDiff()));
        logger.info("absAgeDiff " + absAgeDiff);
        return new String("success");
    }
```
This method calls the getAgeDifference method of DukesBirthdayBean to get the age difference and store it in the ageDiff property, sets the absolute age difference stored in the absAgeDiff property, and returns a status code of success. This status code will be used by the JavaServer Faces runtime to forward the user to the appropriate page.

Right-click in the editor window and select Format.

Select File -> Save.

Creating the Facelets Client

The Facelets client consists of a resource library, a composite component, and two XHTML files.

Resource Libraries in `firstcup`

A JavaServer Faces resource library is a collection of user-created components collected in a standard location in a web application. Resource libraries are identified according to a resource identifier, a string that represents a particular resource within a web application. Resources can be packaged either at the root of the web application or on the web application's classpath.

A resource packaged in the web application root must be in a subdirectory of a resources directory at the web application root.

resources/resource identifier

A resource packaged in the web application classpath must be in a subdirectory of the META-INF/resources directory within a web application.

META-INF/resources/resource identifier

Resource identifiers are unique strings that conform to the following format:

[localePrefix/][libraryName/][libraryVersion/]resource name[/resourceVersion]

Elements of the resource identifier in brackets ([]) are optional. A resource name, identifying a particular resource (a file or a graphic, for example), is required. In firstcup, a resource library with the name components is packaged in the web application root, and this library contains one resource, a file called inputDate.xhtml. The resource identifier for this resource is therefore components/inputDate.xhtml, and it is located in the web application root at resources/components/inputDate.xhtml.

The `inputDate` Composite Component

A composite component is a set of user-defined JavaServerFaces and Facelets components located in a resource. In firstcup, the inputDate.xhtml resource, located in the components resource library is a composite component that contains tags for reading in a date the user enters in a form. Composite components consist of an interface definition and an implementation.

The interface definition is specified with the <composite:interface> tag to define which attributes are exposed to pages that use the composite component. Attributes are identified with the <composite:attribute> tag.

Example 3–2 `inputDate` Composite Component Interface Definition

The inputDate.xhtml interface definition is as follows. It defines a single attribute, date, that must be specified in pages that use the inputDate composite component.

<composite:interface>
    <composite:attribute name="date" required="true" />
</composite:interface>

The implementation of the composite component is specified with the <composite:implementation> tag. The tags within the <composite:implementation> are the actual component tags that will be added to pages that use the composite component. They can be any HTML Render Kit, JavaServer Faces, or Facelets tags. The #{cc.attrs.attribute name} expression is used to get the value of the specified attribute from the page or component that is using the composite component.

Example 3–3 The `inputDate` Composite Component Implementation

The implementation of the inputDate composite component is as follows. An HTML input text component will store the entered text into the date attribute, accessed by the #{cc.attrs.date} expression. A JavaServer Faces convertDateTime component will convert the entered text to a date with the form of MM/dd/yyyy (04/13/2009, for example).

<composite:implementation>
    <h:inputText value="#{cc.attrs.date}">
        <f:convertDateTime pattern="MM/dd/yyyy" />
    </h:inputText>
</composite:implementation>

Creating the `inputDate` Composite Component

Create the inputDate composite component as a resource in the components resource library.

In the firstcup project, select File -> New File.

Select JavaServer Faces under Categories, JSF Composite Component under File Types, and click Next.

In the New JSF Composite Component dialog, enter inputDate under File Name, components under Folder, and click Finish.

Add the composite component interface definition between the <body> and </body> tags in inputDate.xhtml:

	<composite:interface>
		<composite:attribute name="date" required="true" />
	</composite:interface>

Add the composite component implementation below the interface definition:

	<composite:implementation>
		<h:inputText value="#{cc.attrs.date}">
			<f:convertDateTime pattern="MM/dd/yyyy" />
		</h:inputText>
	</composite:implementation>

Right-click in the editor window and select Format.

Select File -> Save.

The Facelets Web Interface

The firstcup web application interface has two XHTML files. The greeting.xhtml file displays Duke's current age and the form to the user for her to enter her birthday. The response.xhtml file displays the age difference between the user and Duke.

The greeting.xhtml contains several pieces of the firstcup application detailed previously. It uses the localized strings contained in WebMessages.properties and WebMessages_es.properties. It uses the DukesBDay managed bean to call both the DukesAgeResource JAX-RS web service and the DukesBirthdayBean enterprise bean. It uses the inputDate composite component to create the input for the user to enter her birthday.

Example 3–4 The `greeting.xhtml` File

Here's the content of the greeting.xhtml file.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html
      PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:fc="http://java.sun.com/jsf/composite/components">
<head>
    <title>Firstcup Greeting Page</title>
</head>
<body>
<h:form>
    <h2>
        <h:outputText value="#{bundle.Welcome}"/>
    </h2>
    <h:outputText value="#{bundle.DukeIs} "/>
    <h:outputText value="#{DukesBDay.age} #{bundle.YearsOldToday}"/>
    <p/>
    <h:outputText value="#{bundle.Instructions}"/>
    <p/>
    <h:outputText value="#{bundle.YourBD} "/>
    <fc:inputDate id="userBirthday" date="#{DukesBDay.yourBD}" />
    <h:outputText value=" #{bundle.Pattern}"/>
    <p/>
    <h:commandButton value="#{bundle.Submit}" action="response"/>
    <p/>
    <h:message for="userBirthday" style="color:red"/>
</h:form>
</body>
</html>

The greeting.xhtml file uses the JSF Core, HTML Render Kit, and the components resource library tag libraries. The components tag library has a prefix of fc, and is used to specify the inputDate composite component in the form below. The <fc:inputDate id="userBirthday" date="#{DukesBDay.yourBD}" /> tag has the required date attribute, and stores the value in the yourBD property in the DukesBDay managed bean by using the EL expression #{DukesBDay.yourBD}.

The localized strings are referred to by using the EL expressions #{bundle.property name}. For example, the <h:outputText value="#{bundle.Welcome}"/> tag will display the following string in English locales:

Hi. I'm Duke. Let's find out who's older -- You or I.

The <h:commandButton value="#{bundle.Submit}" action="response"/> tag creates a submit button and specifies that a successful submission should render the response.xhtml file by setting the action attribute to response. The action attribute is used to define navigation rules for forms in Facelets pages.

If the form submission is unsuccessful, a warning message is displayed. This is done with the <h:message for="userBirthday" style="color:red"/> tag, which is connected to the inputDate composite component with the id userBirthday. That is, if there's an error with the input of the inputDate component, a warning message is displayed.

The response.xhtml displays the age difference between the user and Duke. Different strings are displayed based on whether the user is the same age, younger, or older than duke. The text can be displayed or not based on the conditions specified by the rendered attribute of the <h:outputText> tag. The conditions used in the rendered attribute are EL language alternatives to the Java programming language conditional operators to allow XML parsing of the XHTML file.

Table 3–1 Conditional Operator EL Language Alternatives


Logical Condition	Java Programming Language Conditional Operator	EL Language Alternative
AND	`&&`	`&&`
EQUALS	`==`	`==`
LESS THAN	`<`	`lt`
GREATER THAN	`>`	`gt`

Example 3–5 The `response.xhtml` File

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html
      PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:h="http://java.sun.com/jsf/html">
<head>
    <title>Response Page</title>
</head>
<body>
<h:form>
    <h:outputText value="#{bundle.YouAre} "/>
    <h:outputText value="#{bundle.SameAge}"
                  rendered="#{DukesBDay.ageDiff == 0}"/>
    <h:outputText value="#{DukesBDay.absAgeDiff}"
                  rendered="#{DukesBDay.ageDiff lt 0}"/>
    <h:outputText value=" #{bundle.Year} "
                  rendered="#{DukesBDay.ageDiff == -1}"/>
    <h:outputText value=" #{bundle.Years} "
                  rendered="#{DukesBDay.ageDiff lt -1}"/>
    <h:outputText value="#{bundle.Younger}"
                  rendered="#{DukesBDay.ageDiff lt 0}"/>
    <h:outputText value="#{DukesBDay.absAgeDiff}"
                  rendered="#{DukesBDay.ageDiff gt 0}"/>
    <h:outputText value=" #{bundle.Year} "
                  rendered="#{DukesBDay.ageDiff == 1}"/>
    <h:outputText value=" #{bundle.Years} "
                  rendered="#{DukesBDay.ageDiff gt 1}"/>
    <h:outputText value="#{bundle.Older}" rendered="#{DukesBDay.ageDiff gt 0}"/>    <p/>
    <h:commandButton id="back" value="#{bundle.Back}" action="greeting"/>
</h:form>
</body>
</html>

For example, the #{bundle.SameAge} string is displayed if the user and Duke have the same birthday as specified by the condition #{DukesBDay.ageDiff == 0} in the rendered attribute. That is, display the following string if the ageDiff property of DukesBDay equals 0:

You are the same age as Duke!

The form also contains a <h:commandButton> tag that creates a back button that will direct the user back to the greeting.xhtml page, as specified in the action attribute.

Creating the XHTML Files

Create the Facelets XHTML files in NetBeans IDE.

In the firstcup project select Web Pages in the left pane in NetBeans IDE.

Select File -> New File.

Select Java Server Faces under Categories, New JSF Page under File Types, and click Next.

Enter greeting under File Name and click Finish.

Repeat the previous steps to create a new Facelets Simple File named response.

Set the Welcome File in the `web.xml` Deployment Descriptor

Configure the application to use greeting.xhtml as the welcome file by modifying web.xml

In the firstcup project under Configuration Files double-click web.xml.

Click Pages.

Click Browse under Welcome Files, expand Web Pages, select greeting.xhtml, and click Select File.

Select File -> Save.

Adding Tag Libraries to the XHTML Files

Modify greeting.xhtml to include the components tag library.

In the firstcup project open greeting.xhtml by double-clicking the file name under Web Pages in the left pane.

Add the components tag library to the <html> tag.

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:fc="http://java.sun.com/jsf/composite/components">

The components resource library is referred to by the fc prefix. The JSF Core and HTML Render Kit tag libraries are also used in greeting.xhtml.

Add a title directly after the <html> tag.

<head>
    <title>Firstcup Greeting Page</title>
</head>

Select File -> Save.

Open response.xhtml and add the following title:

<head>
    <title>Response Page</title>
</head>

Select File -> Save.

Adding the Form to `greeting.xhtml`

Add the form that provides the user interface for displaying Duke's age and entering the user's birthday.

In the firstcup project in greeting.xhtml add the following tags between the <body> and </body> tags.

<h:form>
    <h2>
        <h:outputText value="#{bundle.Welcome}"/>
    </h2>
    <h:outputText value="#{bundle.DukeIs} "/>
    <h:outputText value="#{DukesBDay.age} #{bundle.YearsOldToday}"/>
    <p/>
    <h:outputText value="#{bundle.Instructions}"/>
    <p/>
    <h:outputText value="#{bundle.YourBD} "/>
    <fc:inputDate id="userBirthday" date="#{DukesBDay.yourBD}" />
    <h:outputText value=" #{bundle.Pattern}"/>
    <p/>
    <h:commandButton value="#{bundle.Submit}" action="#{DukesBDay.processBirthday}"/>
    <p/>
    <h:message for="userBirthday" style="color:red"/>
</h:form>

Right-click in the editor window and select Format.

Select File -> Save.

Adding the Form to `response.html`

Add a form that displays the age difference between Duke and the user, displays the average age difference of all users, and allows the user to navigate back to greeting.xhtml.

In the firstcup project in response.xhtml add the following tags between the <body> and </body> tags.

<h:form>
    <h:outputText value="#{bundle.YouAre} "/>
    <h:outputText value="#{bundle.SameAge}"
                  rendered="#{DukesBDay.ageDiff == 0}"/>
    <h:outputText value="#{DukesBDay.absAgeDiff}"
                  rendered="#{DukesBDay.ageDiff lt 0}"/>
    <h:outputText value=" #{bundle.Year} "
                  rendered="#{DukesBDay.ageDiff == -1}"/>
    <h:outputText value=" #{bundle.Years} "
                  rendered="#{DukesBDay.ageDiff lt -1}"/>
    <h:outputText value="#{bundle.Younger}"
                  rendered="#{DukesBDay.ageDiff lt 0}"/>
    <h:outputText value="#{DukesBDay.absAgeDiff}"
                  rendered="#{DukesBDay.ageDiff gt 0}"/>
    <h:outputText value=" #{bundle.Year} "
                  rendered="#{DukesBDay.ageDiff == 1}"/>
    <h:outputText value=" #{bundle.Years} "
                  rendered="#{DukesBDay.ageDiff gt 1}"/>
    <h:outputText value="#{bundle.Older}" rendered="#{DukesBDay.ageDiff gt 0}"/>
    <p/>
    <h:outputText value="#{bundle.AverageAge}": #{DukesBday.averageAgeDifference}" />
    <p/>
    <h:commandButton id="back" value="#{bundle.Back}" action="greeting"/>
</h:form>

Right-click in the editor window and select Format.

Select File -> Save.

Setting the Navigation for `firstcup`

Add a navigation rule to faces-config.xml that forwards the user to response.xhtml when the returned status of the DukeBDay.processBirthday method is success.

With the firstcup project selected in the Projects pane, expand Configuration File and double-click faces-config.xml.

Click PageFlow in the top left corner of the editor pane to display the visual navigation editor.

Select greeting.xhtml click and hold the navigation arrow box on the far right, and drag a navigation arrow to the response.xhtml file.

Double-click the default case1 outcome associated with the navigation arrow and change it to success.

Select File -> Save.