Java Server PagesJSP Part II

• Actions

• Beans

• JSP & JDBC

• MVC

2

Agenda

Components

• Scripting Elements

• Directives

• Implicit Objects

• Actions

3

Actions• Actions are XML-syntax tags used to control the servlet engine

• Action elements are basically predefined functions

• <jsp:action_name attribute="value" />

4

Standard Actions

5

JSP Action Tags Description

jsp:forward forwards the request and response to another resource.

jsp:include includes another resource.

jsp:useBean creates or locates bean object.

jsp:setProperty sets the value of property in bean object.

jsp:getProperty prints the value of property of the bean.

jsp:plugin embeds another components such as applet.

jsp:param sets the parameter value. It is used in forward and include mostly.

jsp:fallback can be used to print the message if plugin is working. It is used in jsp:plugin.

include directive and include action

6

JSP include directive JSP include action

includes resource at translation time. includes resource at request time.

better for static pages. better for dynamic pages.

includes the original content in the generated servlet. calls the include method.

Java Beans• A component architecture for Java.

• Useful in JSP for encapsulating application logic and transferring data between pages.

• Beans are simply Java classes.

7

JavaBeans for programmersBeans must:

• Implement java.io.Serializable

• Have a constructor with no argument

Properties (a.k.a. alterable variables) must:

• Must have a get and set

• Must be private attributes

8

JavaBeans example

package mybeans;

import java.io.Serializable;

public class NameBean implements Serializable {

private String fullname;

public NameBean() {

super();

name = new String("World");

}

public void setFullname( String fullname ) {

this.fullname = fullname;

}

public String getFullname() {

return fullname;

}

}

9

<jsp:useBean>• Locates or instantiates a JavaBeans components.

<jsp:useBean id=“beanInstanceName”

scope=“page| request | session |

application”

class=“package.class” />

Example:

10

<jsp:useBean id=“myName” scope=“page”

class=“mybeans.NameBean”/>

<jsp:setProperty>• Sets the value of one or more properties in a Bean, using the Bean’s setter

methods.

• Declare the Bean with <jsp:useBean> first

<jsp:setProperty name=“beanInstanceName”

property=“propertyName”

value=“string” />

Example:

11

<jsp:useBean id=“myName”scope=“page”

class=“mybeans.NameBean”/>

<jsp:setProperty name=“myName”

property=“fullname” value=“abc”/>

<jsp:getProperty>• Gets a Bean property value, using the Bean’s getter methods.

• Declare the Bean with <jsp:useBean>

<jsp:getProperty name=“beanInstanceName”

property=“propertyName” />

Example:

12

<jsp:useBean id=“myName”scope=“page”

class=“mybeans.NameBean”/>

<H1>My Name <jsp:getProperty name=“myName”

property=“fullname”/>

</H1>

Expression Language (EL)Simplifies the accessibility of data stored in the Java Bean component, and other objects like

request, session, application etc.

${ expression }

13

<form action="process.jsp">

Enter Name:<input type="text" name=“input" /><br/><br/>

<input type="submit" value="go"/>

</form>

Welcome, ${ param.input }

Implicit Objects in EL

14

Implicit Objects Usage

pageScope it maps the given attribute name with the value set in the page scope

requestScope it maps the given attribute name with the value set in the request scope

sessionScope it maps the given attribute name with the value set in the session scope

applicationScope it maps the given attribute name with the value set in the application scope

param it maps the request parameter to the single value

paramValues it maps the request parameter to an array of values

header it maps the request header name to the single value

headerValues it maps the request header name to an array of values

cookie it maps the given cookie name to the cookie value

initParam it maps the initialization parameter

pageContext it provides access to many objects request, session etc.

Expression Language (EL)

15

<%

session.setAttribute("user",“abc");

%>

Value is ${ sessionScope.user }

<%

Cookie ck=new Cookie("name",“xyz");

response.addCookie(ck);

%>

Hello, ${cookie.name.value}

JSP & JDBC<%@page import="java.sql.*,java.util.*"%><html> <body>

<%try {

Class.forName("com.mysql.jdbc.Driver");Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/students", "root",

"password");Statement stmt = con.createStatement();ResultSet rs = stmt.executeQuery("select * from btcse");

%><table border=1 bgcolor="orange"><%

while (rs.next()) {%>

<tr><td><%=rs.getString("ENROLLMENT_NUMBER")%></td><td><%=rs.getString("STUDENT_NAME")%></td>

</tr><%

}con.close();

} catch (Exception e) {System.out.println(e);

}

%></table></body></html>

16

MVC: Model, View, Controller• Model 1

• Model 2

17

MVC

18

References

• https://docs.oracle.com/javaee/5/tutorial/doc/bnagx.html

• https://www.javatpoint.com/jsp-tutorial

19

Thank you

20