The guessnumber-cdi CDI Example
The guessnumber-cdi example, somewhat more complex than the
simplegreeting example, illustrates the use of producer methods and of
session and application scope. The example is a game in which you try to
guess a number in fewer than ten attempts. It is similar to the
guessnumber-jsf example described in
Chapter 8, "Introduction to Facelets",
except that you can keep guessing until you get the right answer or
until you use up your ten attempts.
The example includes four source files, a Facelets page and template,
and configuration files. The configuration files and the template are
the same as those used for the simplegreeting example.
The following topics are addressed here:
The guessnumber-cdi Source Files
The four source files for the guessnumber-cdi example are:
-
The
@MaxNumberqualifier interface -
The
@Randomqualifier interface -
The
Generatormanaged bean, which defines producer methods -
The
UserNumberBeanmanaged bean
The source files are located in the
tut-install/examples/cdi/guessnumber-cdi/src/main/java/javaeetutorial/guessnumber
directory.
The @MaxNumber and @Random Qualifier Interfaces
The @MaxNumber qualifier interface is defined as follows:
package guessnumber;
import java.lang.annotation.Documented;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.ElementType.TYPE;
import java.lang.annotation.Retention;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Target;
import javax.inject.Qualifier;
@Target({TYPE, METHOD, PARAMETER, FIELD})
@Retention(RUNTIME)
@Documented
@Qualifier
public @interface MaxNumber {
}
The @Random qualifier interface is defined as follows:
package guessnumber;
import java.lang.annotation.Documented;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.ElementType.TYPE;
import java.lang.annotation.Retention;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Target;
import javax.inject.Qualifier;
@Target({TYPE, METHOD, PARAMETER, FIELD})
@Retention(RUNTIME)
@Documented
@Qualifier
public @interface Random {
}
The Generator Managed Bean
The Generator managed bean contains the two producer methods for the
application. The bean has the @ApplicationScoped annotation to specify
that its context extends for the duration of the user’s interaction with
the application:
package guessnumber;
import java.io.Serializable;
import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.inject.Produces;
@ApplicationScoped
public class Generator implements Serializable {
private static final long serialVersionUID = -7213673465118041882L;
private final java.util.Random random =
new java.util.Random( System.currentTimeMillis() );
private final int maxNumber = 100;
java.util.Random getRandom() {
return random;
}
@Produces @Random int next() {
return getRandom().nextInt(maxNumber + 1);
}
@Produces @MaxNumber int getMaxNumber() {
return maxNumber;
}
}
The UserNumberBean Managed Bean
The UserNumberBean managed bean, the managed bean for the JavaServer
Faces application, provides the basic logic for the game. This bean does
the following:
-
Implements setter and getter methods for the bean fields
-
Injects the two qualifier objects
-
Provides a
resetmethod that allows you to begin a new game after you complete one -
Provides a
checkmethod that determines whether the user has guessed the number -
Provides a
validateNumberRangemethod that determines whether the user’s input is correct
The bean is defined as follows:
package guessnumber;
import java.io.Serializable;
import javax.annotation.PostConstruct;
import javax.enterprise.context.SessionScoped;
import javax.enterprise.inject.Instance;
import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.component.UIInput;
import javax.faces.context.FacesContext;
import javax.inject.Inject;
import javax.inject.Named;
@Named
@SessionScoped
public class UserNumberBean implements Serializable {
private static final long serialVersionUID = -7698506329160109476L;
private int number;
private Integer userNumber;
private int minimum;
private int remainingGuesses;
@MaxNumber
@Inject
private int maxNumber;
private int maximum;
@Random
@Inject
Instance<Integer> randomInt;
public UserNumberBean() {
}
public int getNumber() {
return number;
}
public void setUserNumber(Integer user_number) {
userNumber = user_number;
}
public Integer getUserNumber() {
return userNumber;
}
public int getMaximum() {
return (this.maximum);
}
public void setMaximum(int maximum) {
this.maximum = maximum;
}
public int getMinimum() {
return (this.minimum);
}
public void setMinimum(int minimum) {
this.minimum = minimum;
}
public int getRemainingGuesses() {
return remainingGuesses;
}
public String check() throws InterruptedException {
if (userNumber > number) {
maximum = userNumber - 1;
}
if (userNumber < number) {
minimum = userNumber + 1;
}
if (userNumber == number) {
FacesContext.getCurrentInstance().addMessage(null,
new FacesMessage("Correct!"));
}
remainingGuesses--;
return null;
}
@PostConstruct
public void reset() {
this.minimum = 0;
this.userNumber = 0;
this.remainingGuesses = 10;
this.maximum = maxNumber;
this.number = randomInt.get();
}
public void validateNumberRange(FacesContext context,
UIComponent toValidate,
Object value) {
int input = (Integer) value;
if (input < minimum || input > maximum) {
((UIInput) toValidate).setValid(false);
FacesMessage message = new FacesMessage("Invalid guess");
context.addMessage(toValidate.getClientId(context), message);
}
}
}
The Facelets Page
This example uses the same template that the simplegreeting example
uses. The index.xhtml file, however, is more complex.
<?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 lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
xmlns:h="http://xmlns.jcp.org/jsf/html">
<ui:composition template="/template.xhtml">
<ui:define name="title">Guess My Number</ui:define>
<ui:define name="head">Guess My Number</ui:define>
<ui:define name="content">
<h:form id="GuessMain">
<div style="color: black; font-size: 24px;">
<p>I'm thinking of a number from
<span style="color: blue">#{userNumberBean.minimum}</span>
to
<span style="color: blue">#{userNumberBean.maximum}</span>.
You have
<span style="color: blue">
#{userNumberBean.remainingGuesses}
</span>
guesses.</p>
</div>
<h:panelGrid border="0" columns="5" style="font-size: 18px;">
<h:outputLabel for="inputGuess">Number:</h:outputLabel>
<h:inputText id="inputGuess"
value="#{userNumberBean.userNumber}"
required="true" size="3"
disabled="#{userNumberBean.number eq userNumberBean.userNumber or userNumberBean.remainingGuesses le 0}"
validator="#{userNumberBean.validateNumberRange}">
</h:inputText>
<h:commandButton id="GuessButton" value="Guess"
action="#{userNumberBean.check}"
disabled="#{userNumberBean.number eq userNumberBean.userNumber or userNumberBean.remainingGuesses le 0}"/>
<h:commandButton id="RestartButton" value="Reset"
action="#{userNumberBean.reset}"
immediate="true" />
<h:outputText id="Higher" value="Higher!"
rendered="#{userNumberBean.number gt userNumberBean.userNumber and userNumberBean.userNumber ne 0}"
style="color: #d20005"/>
<h:outputText id="Lower" value="Lower!"
rendered="#{userNumberBean.number lt userNumberBean.userNumber and userNumberBean.userNumber ne 0}"
style="color: #d20005"/>
</h:panelGrid>
<div style="color: #d20005; font-size: 14px;">
<h:messages id="messages" globalOnly="false"/>
</div>
</h:form>
</ui:define>
</ui:composition>
</html>
The Facelets page presents the user with the minimum and maximum values
and the number of guesses remaining. The user’s interaction with the
game takes place within the panelGrid table, which contains an input
field, Guess and Reset buttons, and a field that appears if the guess is
higher or lower than the correct number. Every time the user clicks
Guess, the userNumberBean.check method is called to reset the
maximum or minimum value or, if the guess is correct, to generate a
FacesMessage to that effect. The method that determines whether each
guess is valid is userNumberBean.validateNumberRange.
Running the guessnumber-cdi Example
You can use either NetBeans IDE or Maven to build, package, deploy, and
run the guessnumber-cdi application.
The following topics are addressed here:
To Build, Package, and Deploy the guessnumber-cdi Example Using NetBeans IDE
-
Make sure that GlassFish Server has been started (see Starting and Stopping GlassFish Server).
-
From the File menu, choose Open Project.
-
In the Open Project dialog box, navigate to:
-
Select the
guessnumber-cdifolder. -
Click Open Project.
-
In the Projects tab, right-click the
guessnumber-cdiproject and select Build.This command builds and packages the application into a WAR file,
guessnumber-cdi.war, located in thetargetdirectory, and then deploys it to GlassFish Server.
To Build, Package, and Deploy the guessnumber-cdi Example Using Maven
-
Make sure that GlassFish Server has been started (see Starting and Stopping GlassFish Server).
-
In a terminal window, change to the following directory:
tut-install/examples/cdi/guessnumber-cdi/ -
Enter the following command to deploy the application:
This command builds and packages the application into a WAR file,
guessnumber-cdi.war, located in thetargetdirectory, and then deploys it to GlassFish Server.
To Run the guessnumber Example
-
In a web browser, enter the following URL:
http://localhost:8080/guessnumber-cdiThe Guess My Number page opens.
-
On the Guess My Number page, enter a number in the Number field and click Guess.
The minimum and maximum values are modified, along with the remaining number of guesses.
-
Keep guessing numbers until you get the right answer or run out of guesses.
If you get the right answer or run out of guesses, the input field and Guess button are grayed out.
-
Click Reset to play the game again with a new random number.