JSP Actions

What are JSP Actions?

JSP actions are XML-based tags that control the behavior of the Servlet engine. Unlike directives (which affect translation), actions affect the runtime behavior of the JSP. They use the jsp: prefix and follow XML syntax.

Action Tag	Description
`<jsp:include>`	Dynamically includes another resource at request time
`<jsp:forward>`	Forwards the request to another resource
`<jsp:useBean>`	Instantiates or locates a JavaBean
`<jsp:setProperty>`	Sets a property on a JavaBean
`<jsp:getProperty>`	Gets a property from a JavaBean
`<jsp:param>`	Passes parameters to included/forwarded pages

jsp:include and jsp:forward

<%@ page language="java" contentType="text/html; charset=UTF-8"%>
<html><body>

<h2>jsp:include - Dynamic Include</h2>
<%-- Includes header.jsp at request time (dynamic) --%>
<jsp:include page="header.jsp">
    <jsp:param name="title" value="My Page Title"/>
    <jsp:param name="color" value="blue"/>
</jsp:include>

<p>Main page content here.</p>

<%-- Include a dynamic page --%>
<jsp:include page="sidebar.jsp" flush="true"/>

<%-- jsp:forward - Forwards request to another page --%>
<%
    String role = (String) session.getAttribute("role");
    if (role == null) {
%>
    <jsp:forward page="login.jsp">
        <jsp:param name="message" value="Please login first"/>
    </jsp:forward>
<%
    }
%>

</body></html>

jsp:useBean, setProperty, getProperty

These three actions work together to integrate JavaBeans into JSP pages. A JavaBean is a reusable Java class with private fields and public getter/setter methods.

JavaBean and JSP Actions

package com.example.beans;

// JavaBean: must have no-arg constructor and getter/setters
public class UserBean {
    private String name;
    private String email;
    private int age;

    // No-argument constructor (required for JavaBean)
    public UserBean() {}

    public String getName() { return name; }
    public void setName(String name) { this.name = name; }

    public String getEmail() { return email; }
    public void setEmail(String email) { this.email = email; }

    public int getAge() { return age; }
    public void setAge(int age) { this.age = age; }

    public String getInfo() {
        return name + " (" + age + ") - " + email;
    }
}

<%@ page language="java" contentType="text/html; charset=UTF-8"%>
<html><body>

<%-- Create/locate a UserBean in session scope --%>
<jsp:useBean id="user" class="com.example.beans.UserBean" scope="session"/>

<%-- Set properties from request parameters automatically --%>
<jsp:setProperty name="user" property="*"/>

<%-- Or set individual properties --%>
<jsp:setProperty name="user" property="name" value="Alice"/>
<jsp:setProperty name="user" property="email" param="userEmail"/>
<jsp:setProperty name="user" property="age" value="25"/>

<h2>User Information</h2>
<p>Name: <jsp:getProperty name="user" property="name"/></p>
<p>Email: <jsp:getProperty name="user" property="email"/></p>
<p>Age: <jsp:getProperty name="user" property="age"/></p>
<p>Info: <%= user.getInfo() %></p>

</body></html>

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JSP Actions

What are JSP Actions?

jsp:useBean, setProperty, getProperty

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