pre-assessment questions

Introducing JavaBeans

Lesson 2A / Slide 1 of 30JDBC and JavaBeans

Pre-assessment Questions1. Which of the given symbols is used as a placeholder for PreparedStatement?

a. #b. *c. ?d. %

2. In SQL Server 2000, a _______ is generated when you execute a stored procedure. a. Query planb. Queryc. ResultSetd. Rowset



Pre-assessment Questions (Contd.)3. Which of the following parameters cannot be used in a stored procedure?

a. IN

b. OUT

c. OUTIN

d. INOUT

4. Which of the following enables you to retrieve the information about a ResultSet?a. DatabaseMetaData

b. ResultSetData

c. RowSetData

d. ResultSetMetaData



Pre-assessment Questions (Contd.)5. The batch update operations can throw two types of exceptions,

__________and ___________. a. SQLException and BatchUpdateExceptionb. SQLException and UpdateExceptionc. BatchException and BatchUpdateExceptiond. BatchException and SQLException



Solutions to Pre-assessment Questions

1. c. ?2. a. Query plan3. c. OUTIN4. d. ResultSetMetaData5. a. SQLException and BatchUpdateException



ObjectivesIn this lesson, you will learn about:

• Features of JavaBeans

• Associating predefined events with sample JavaBeans

• Testing JavaBeans using BDK

• Creating sample JavaBean applet using BDK

• Creating user-defined JavaBean

• Creating manifest and JAR files for a JavaBean



JavaBean Concepts• A software component is a reusable object that can be plugged into any target

software application.

• You can develop software components using various programming languages, such as C, C++, Java, and Visual Basic.

• JavaBeans are reusable and platform-independent software components developed using the Java programming language.

• The classes and interfaces defined in the java.beans package enable you to create JavaBeans.

• The JavaBean components can exist in one of the following three phases of development:

• Construction phase

• Build phase

• Execution phase



JavaBean Concepts (Contd.)• Elements of a JavaBean

• Properties: Refer to the private data members of a JavaBean that define the behavior of the JavaBeans.

• Methods: Refer to public member functions of a JavaBean that are used to modify the JavaBean properties.

• Events: Refer to the messages that one JavaBean components sends to another JavaBean components.



JavaBean Concepts (Contd.)• The JavaBean Component Specification

• Customization: Is the ability of JavaBean to allow its properties to be changed in build and execution phase.

• Persistence: Is the ability of JavaBean to save its state to disk or storage device and restore the saved state when the JavaBean is reloaded.

• Communication: Is the ability of JavaBean to notify change in its properties to other JavaBeans or the container.

• Introspection: Is the ability of a JavaBean to allow an external application to query the properties, methods, and events supported by it.



JavaBean Concepts (Contd.)• Services of JavaBean Components

• Builder support: Enables you to create and group multiple JavaBeans in an application.

• Layout: Allows multiple JavaBeans to be arranged in a development environment.

• Interface publishing: Enables multiple JavaBeans in an application to communicate with each other.

• Event handling: Refers to firing and handling of events associated with a JavaBean.

• Persistence: Enables you to save the last state of JavaBean.



JavaBean Concepts (Contd.) • Types of JavaBeans

• Control JavaBeans: Are used to create GUI components that can be plugged into any application.

• Container JavaBeans: Are used to hold other JavaBeans.

• Invisible Runtime JavaBeans: Are used to create components that perform a specific task in the background of an application.



Beans Development Kit • Is a development environment to create, configure, and test JavaBeans.

• The features of BDK environment are:

• Provides a GUI to create, configure, and test JavaBeans.

• Enables you to modify JavaBean properties and link multiple JavaBeans in an application using BDK.

• Provides a set of sample JavaBeans.

• Enables you to associate pre-defined events with sample JavaBeans.



Beans Development Kit (Contd.)

• Identifying BDK Components

• Execute the run.bat file of BDK to start the BDK development environment.

• The components of BDK development environment are:

• ToolBox

• BeanBox

• Properties

• Method Tracer




• ToolBox window: Lists the sample JavaBeans of BDK.

• The following figure shows the ToolBox window:




• BeanBox window: Is a workspace for creating the layout of JavaBean application.

• The following figure shows the BeanBox window:




• Properties window: Displays all the exposed properties of a JavaBean. You can modify JavaBean properties in the properties window.

• The following figure shows the Properties window:




• Method Tracer window: Displays the debugging messages and method calls for a JavaBean application.

• The following figure shows the Method Tracer window:



Demonstration-Creating Sample JavaBean Applet using BDK

• Problem Statement

• Create an applet that shows the sample Molecule JavaBean rotating along its X-axis.



Demonstration-Creating Sample JavaBean Applet using BDK (Contd.)• Solution

• To create an applet that shows a Molecule JavaBean rotating along its X-axis, you need to perform the following tasks: 1. Associating pre-defined event with sample JavaBeans.2. Converting the JavaBean to an applet.



User-Defined JavaBean• The coding conventions to create a user-defined JavaBean are:

• Implement the java.io.Serializable interface.

• Define an empty constructor to initialize the instances of a JavaBean.

• Define the accessor and mutator methods for the exposed properties of a JavaBean.



User-Defined JavaBean (Contd.)• Accessor and Mutator Methods:

• Are used to access the exposed properties of a JavaBean.

• The accessor methods:

• Are used to retrieve the values of JavaBean properties.

• Are also called get methods.

• The mutator methods:

• Are used to specify the values of JavaBean properties.

• Are also called set methods.



User-Defined JavaBean (Contd.)• Manifest and JAR Files

• Manifest File

• The manifest file for a JavaBean application contains a list of all the class files that make up a JavaBean.

• The entry in the manifest file enables the target application to recognize the JavaBean classes for an application.

• For example, the entry for the SpellCheck JavaBean in the manifest file is as shown:Name: SpellCheck.class

Java-Bean: True



User-Defined JavaBean (Contd.)• Manifest File (Contd.)

• The rules to create a manifest file are:

• Press the Enter key after typing each line in the manifest file.

• Leave a space after the colon.

• Type a hyphen between Java and Bean.

• No blank line between the Name and the Java-Bean entry.



User-Defined JavaBean (Contd.)• Java Archive File

• The files of a JavaBean application are compressed and grouped as JAR files to reduce the size and the download time of the files.

• The syntax to create a JAR file from the command prompt is:jar <options> <file_names>

• The file_names is a list of files for a JavaBean application that are stored in the JAR file.



User-Defined JavaBean (Contd.)• Java Archive File (Contd.)

• The various options that you can specify while creating a JAR file are:

•c: Indicates the new JAR file is created.

•f: Indicates that the first file in the file_names list is the name of the JAR file.

•m: Indicates that the second file in the file_names list is the name of the manifest file.

•t: Indicates that all the files and resources in the JAR file are to be displayed in a tabular format.

•v: Indicates that the JAR file should generate a verbose output.

•x: Indicates that the files and resources of a JAR file are to be extracted.

•o: Indicates that the JAR file should not be compressed.

•m: Indicates that the manifest file is not created.



Demonstration-Creating User-Defined JavaBean

• Problem Statement

• Create a user-defined JavaBean having a label. Allow the user to change the caption of the user-defined JavaBean at runtime.



Demonstration-Creating User-Defined JavaBean (Contd.)• Solution

• To create a user-defined JavaBean that changes the caption of a label, you need to perform the following tasks:1. Code the user-defined JavaBean2. Package the JavaBean3. Load and test the JavaBean



Summary In this lesson, you learned:

• A component is a reusable object that can be plugged into any target software application.

• JavaBeans are reusable and platform-independent software components that are created using the Java programming language.

• The various features of JavaBean are:

• Customization

• Persistence

• Communication

• Introspection



Summary (Contd.) • JavaBean components provide the following services to the container in

which they are grouped together:

• Builder support

• Layout

• Interface publishing

• Event handling

• Persistence

• There are three types of JavaBeans, Control JavaBeans, Container JavaBeans, and Invisible runtime JavaBeans.

• BDK is a development environment to test and create JavaBeans.

• The ToolBox window of BDK displays the sample JavaBeans defined in the BDK.

• The BeanBox window of BDK enables you to test JavaBeans and create applications using various JavaBeans as components.



Summary (Contd.) • The properties window displays the properties of the currently selected

JavaBean component.

• The method tracer window of BDK displays the debugging messages and method calls for the BDK environment.

• BDK provides pre-defined events that can be associated with the sample JavaBean components in an application.

• The pre-defined events for the sample JavaBeans are displayed in the EventTargetDialog window of BDK.

• The MakeApplet utility of BDK enables you to create an applet file for a JavaBean application. The applet file can be run using a Web browser or the applet viewer utility of Java.

• You can also create user-defined JavaBeans using the classes and interfaces provided by the java.beans package.



Summary (Contd.) • The accessor and mutator methods of user-defined JavaBean are used to

retrieve and specify the value of JavaBean properties.

• The user-defined JavaBean implements the java.io.Serializable interface.

• A manifest file is a text file that provides information about the class files that represent a JavaBean.

• JAR files are platform-independent files that are used to package all the classes and the associated resources for a JavaBean application.

• The JAR file for the user-defined JavaBean is loaded in the ToolBox window using the FileLoadJar command of the BeanBox window.

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