JavaBeans are usual Java classes which adhere to certain coding conventions. A JavaBean can be defined as a reusable software component. A JavaBean is a Java Object that is serializable, has a 0-argument constructor, and allows access to properties using getter and setter methods. We can write a JavaBean that can then be used in a variety of other Java based software such as applications, Servlets or JSP pages. In this way we can define our business logic within a JavaBean and then consistently use that logic in separate applications.
JavaBeans is an architecture for both using and building components in Java. This architecture supports the features of software reuse, component models, and object orientation. One of the most important features of JavaBeans is that it does not alter the existing Java language. If you know how to write software in Java, you know how to use and create Beans. The strengths of Java are built upon and extended to create the JavaBeans component architecture.
JavaBeans components are simple to create and easy to use. This is an important goal of the JavaBeans architecture. It doesn’t take very much to write a simple Bean, and such a Bean is lightweight. JavaBeans doesn’t have to carry around a lot of inherited baggage just to support the Beans environment. If a Bean does not require the advanced features of the architecture, it doesn’t get them, nor does it get the code that goes with them. This is an important concept. The JavaBeans architecture scales upward in complexity, not downward like other component models. This means it really is easy to create a simple Bean.
Advantages of JavaBeans:
* JavaBeans can also have a visual component in a manner similar to the ActiveX controls that can be dragged-and-dropped into a Visual Basic application.
* JavaBeans are used to encapsulate many objects into a single object (the bean), so that they can be passed around as a single bean object instead of as multiple individual objects.
* JavaBeans gives Java applications the compound document capability that the OpenDoc and ActiveX interfaces already provide.
* JavaBeans components (or “Beans”) can be used to give World Wide Web pages (or other applications) interactive capabilities such as computing interest rates or varying page content based on user or browser characteristics.
* JavaBeans is Java’s component model. It allows users to construct applications by piecing components together either programmatically or visually (or both). Support of visual programming is paramount to the component model; it’s what makes component-based software development truly powerful.
* Since JavaBeans components are built purely in Java, they are fully portable to any platform that supports the Java run-time environment. All platform specifics, as well as support for JavaBeans, are implemented by the Java virtual machine.
* JavaBeans uses the existing Java class discovery mechanism. This means that there isn’t some new complicated mechanism for registering components with the run-time system.
* The JavaBeans would take over when you need to perform some complex data processing or when you need to access databases or the file system.
* By using JavaBeans you can fully separate the business logic from the generation of the display.
* The other advantage of using JavaBeans is that the business logic can be used by more than one application. For example, both a client based Java application and a JSP page can access the same JavaBean thus guaranteeing the same functionality.
* By using JavaBeans you can split your development team into Java experts and HTML experts. The Java experts would write and develop the JavaBeans and the HTML experts would concentrate of the design of the web application.
Finally, a JavaBean may be designed to work autonomously on a user’s workstation or to work in cooperation with a set of other distributed components.