JSP JavaBean Components

A JavaBeans component is a Java class with the following features:

• A no-argument constructor.
• Properties defined with accessors and mutators(getter and setter method).
• Class must not define any public instance variables.
• The class must implement the java.io.Serializable interface.

Example of a JavaBean

Let's take a simple Java code example to understand what do we mean when we say JavaBean,

import java.io.Serializable;

public class StudentBean implements Serializable
{
  private String name;
  private int roll;

  // constructor
  public StudentBean()
  {
    this.name = "";
    this.roll = "";
  }
  // getters and setters
  public void setName(String name)
  {
    this.name = name;
  }
  public String getName()
  {
    return name;
  }
  public int getRoll()
  {
    return roll;
  }
  public void setRoll(int roll)
  {
    this.roll = roll;
  }
}

As you can see in the code above, a JavaBean is nothing but a Java class which implements the interface Serializable.

Using a JavaBean in JSP page

JavaBeans can be used in any JSP page using the <jsp:useBean> tag, For example:

<jsp:useBean id="bean name" scope="fully qualified path of bean" typeSpec/>

Using any JavaBean property in JSP page

JavaBeans can be used in any JSP page using the <jsp:useBean> tag, <jsp:setProperty> tag and <jsp:getProperty> tag , For example:

<jsp:useBean id="id" class="bean class name" scope="fully qualified path of bean">
   <jsp:setProperty name="beans id" property="property name" value="value"/>
   <jsp:getProperty name="beans id" property="property name"/>
   ...........
</jsp:useBean>

We will learn about the jsp:useBean tag in details in the next tutorial.