Differences JSP Custom Tags vs Java Beans
JSP Custom Tags and JavaBeans are both used in JSP to enhance functionality and facilitate code reuse, but they serve different purposes and are used in different ways. Here’s a breakdown of the major differences between JSP and JavaBeans.
JSP Custom Tags
JSP Custom Tags are user-defined tags that encapsulate reusable functionality in a JSP page. They are defined in tag libraries (TagLib) and can be used to abstract complex operations into simple tags.
Characteristics
- Tag Libraries : Custom tags are grouped into tag libraries that can be imported into a JSP page.
- Complex Logic : They can encapsulate complex logic that would otherwise clutter the JSP page.
- Reusability : They promote reusability and separation of concerns by moving business logic out of JSP pages.
- Attributes : Custom tags can accept attributes to control their behavior.
- Tag Handlers : They require the implementation of tag handler classes that define the behavior of the custom tags.
Table of Contents
Example
Example:
Tag Library Descriptor (TLD) :
xml
<tag>
<name>helloTag</name>
<tag-class>com.example.HelloTag</tag-class>
<body-content>empty</body-content>
</tag>
Custom Tag Handler Class :
java
public class HelloTag extends TagSupport {
public int doStartTag() throws JspException {
try {
pageContext.getOut().print("Hello, Custom Tag!");
} catch (IOException e) {
throw new JspException(e);
}
return SKIP_BODY;
}
}
Using the Custom Tag in JSP :
jsp
<%@ taglib uri="http://example.com/tags" prefix="ex" %>
<ex:helloTag />
JavaBeans
JavaBeans are reusable software components that follow specific conventions. They are used to encapsulate data and business logic in a reusable, modular way.
Characteristics:
- Properties : JavaBeans have properties that can be accessed using getter and setter methods.
- Encapsulation : They encapsulate data and provide a clear interface for manipulating that data.
- Reusability : They promote reusability and modularity.
- Serializable : JavaBeans must implement the Serializable interface.
- No-Argument Constructor: They must have a no-argument constructor.
Example
Example:
JavaBean Class :
java
public class User implements Serializable {
private String name;
private int age;
public User() {}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
Using JavaBean in JSP :
jsp
<jsp:useBean id="user" class="com.example.User" scope="session" />
<jsp:setProperty name="user" property="name" value="John Doe" />
<jsp:setProperty name="user" property="age" value="30" />
<p>Name: <jsp:getProperty name="user" property="name" /></p>
<p>Age: <jsp:getProperty name="user" property="age" /></p>
Major Differences
1. Â Purpose
- Â JSP Custom Tags : Used to encapsulate complex logic and functionality in reusable tags.
- Â JavaBeans : Used to encapsulate data and business logic in a reusable, modular way.
2. Â Implementation
- JSP Custom Tags : Require the creation of tag libraries and tag handler classes.
- JavaBeans : Require the creation of classes following the JavaBeans conventions (properties, getters/setters, no-argument constructor, Serializable interface).
3. Â Usage
- JSP Custom Tags : Used directly in JSP pages to simplify complex operations and improve readability.
- JavaBeans : Used to manage data and business logic, often accessed and manipulated in JSP pages using <jsp:useBean>, <jsp:setProperty>, and <jsp:getProperty> tags.
4. Â Complexity
- JSP Custom Tags : Can handle more complex operations and logic than JavaBeans.
- JavaBeans : Primarily used for data encapsulation and simple business logic.
5. Â Attributes vs Properties :
- JSP Custom Tags : Accept attributes to control their behavior.
- JavaBeans : Have properties accessed via getter and setter methods.