Java bean
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This document discusses JavaBeans and their use in both window and web applications. It defines JavaBeans as reusable software components that allow developers to reuse code without understanding inner workings. It provides examples of common reusable components like buttons and text fields. It also describes JavaBean properties as readable and writable attributes accessed via getter and setter methods, and how to declare and access JavaBeans in JSP files using the useBean tag. The document demonstrates how to work with JavaBeans in NetBeans.
Java bean
- 1. JavaBeans (DemoinNetBeans) Presented by: Roll No’s: 801331002 801331003 801331004 801331029 Branch: SE
- 2. JavaBeans JavaBeans™ makes it easy to reuse software components. Developers can use software components written by others without having to understand their inner workings.
- 3. Types of JavaBeans 1. Window application using JavaBeans. 2. Web applications using JavaBeans.
- 4. Reuseable components in netbeans for Window application Button Labels Text Field Check Box Combo Box Radio Button ETC.
- 5. Properties of javabean •It may have a number of properties which can be read or written. •It may have a number of "getter" and "setter" methods for the properties.
- 7. Web applications usingJavaBeans By using concrete classes. By using library
- 8. JavaBeans Properties A JavaBean property is a named attribute that can be accessed by the user of the object. A JavaBean property may be read, write, read only, or write only. JavaBean properties are accessed through two methods in the JavaBean's implementation class:
- 9. Methods Method Description getPropertyName() For example, if property name is firstName, your method name would be getFirstName() to read that property.This method is called accessor. setPropertyName() For example, if property name is firstName, your method name would be setFirstName() to write that property.This method is called mutator.
- 10. Accessing JavaBeans: • The useBean action declares a JavaBean for use in a JSP. • Once declared, the bean becomes a scripting variable that can be accessed by both scripting elements and other custom tags used in the JSP. • The full syntax for the useBean tag is as follows: <jsp:useBean id="bean's name" scope="bean's scope" class=“classname”/>
- 11. Syntax elaborated <jsp:useBean id="bean's name" scope="bean's scope" class=“classname”/> “Id” attribute specify the object name. “Scope” attribute will specify scope of that bean. eg. Session etc. “class” attribute specify the package that contains the class and class name that is used as bean.