Download presentation
Presentation is loading. Please wait.
1
Java Server Pages JSP 11/11/2018
2
Concept: Server-side programming
CGI scripts servlet Java program that runs on webserver Called from html page Follows Sun servlet standard JavaServer page (JSP) Contains html and Java or JavaScript Compiled into a servlet and run on server 11/11/2018 Copyright Ege Consulting, Inc.
3
JSP is servlet follows request-response model loaded into webserver
webserver manages instance typical logic examine request: parameters, session, cookies, context produce response add to output stream 11/11/2018
4
JSP page stored with extension “.jsp” contains html
JSP scripting elements JSP directives JSP actions JSP comment <% %> 11/11/2018
5
JSP scripting elements
declaration <%! %> expression <%= %> scriptlet <% %> 11/11/2018
6
JSP declaration placed into servlet outside of service method
<%! int accessCount = 0; %> 11/11/2018
7
JSP expression expression is evaluated and placed into output
This page has been accessed <%= accessCount %> times 11/11/2018
8
JSP scriptlet code that is inserted into service method
<% accessCount += 1; %> 11/11/2018
9
first JSP example <html>
<head><title>Very Simple JSP</title></head> <body> <h1>Very Simple JSP</h1> <%! int accessCount = 0; %> This page has been accessed <%= accessCount %> times <% accessCount += 1; %> </body> </html> 11/11/2018
10
Run from Internet explorer
11/11/2018
11
JSP directives control overall structure of servlet include
used to include another file include file=“relative URL” %> URL may start with “/” 11/11/2018
12
JSP directive: page has attributes import content-type isThreadSafe
to add import statements to servlet page import=“java.util.*” %> content-type isThreadSafe value “true” is default “false” makes servlet implement SingleThreadModel 11/11/2018
13
JSP page directive: more attributes
session value “true” is default “false” disables session management buffer="sizekb|none“ specifies the buffer size for the JspWriter out autoflush="true|false” extends="package.class” info="message” errorPage="url” isErrorPage="true|false” language="java" 11/11/2018
14
Predefined variables request response instance of HttpServletRequest
ex: request.getParameter(“username); response instance of HttpServletResponse ex: response.addCookie(myCookie); 11/11/2018
15
Predefined variables out same as html text outside of <% … %>
instance of JSPWriter buffered version of output stream ex: out.println(“hello world”); same as html text outside of <% … %> 11/11/2018
16
Predefined variables session instance of HttpSession
only available if session attribute of page %> directive is true ex: session.setAttribte(“user”, “John Doe”); ex: name = (String) session.getAttribute(“user”); 11/11/2018
17
Predefined variables application config page instance of HttpContext
ex: application.setAttribute(“user”, “John Doe”); ex: name = (String)application.getAttribute(“user); config instance of HttpConfig page same as “this” in Java 11/11/2018
18
JSP example: second.jsp
<html><head><title>Session JSP</title></head><body> <h1>Welcome to our World</h1> page session="true" %> <form action="second.jsp"> <% if (session.isNew()) { %> Enter your ID: <input type="text" name="username"> <% } else { String name = request.getParameter("username"); if (name == null) name = (String)session.getAttribute("user"); else session.setAttribute("user", name); %> Welcome back <%= name %> <% } %> <input type="submit"></form> </body></html> 11/11/2018
19
Run and observe JSP 11/11/2018
20
JSP actions jsp:include jsp:forward jsp:useBean jsp:setProperty
include a file at the time the page is requested jsp:forward forward the requester to a new page jsp:useBean find or instantiate a JavaBean jsp:setProperty set the property of a JavaBean jsp:getProperty insert the property of a JavaBean into the output jsp:plugin 11/11/2018
21
jsp:include action <jsp:include page="relative URL" flush="true" /> inserts the file at the time the JSP page is translated into a servlet similar to “include” method of RequestDispatcher 11/11/2018
22
jsp:forward action forwards the request to another page
<jsp:forward page="relative URL" /> forwards the request to another page similar to “forward” method of RequestDispatcher examples: <jsp:forward page="errorReporter.jsp" /> 11/11/2018
23
Exercise: shopping cart
11/11/2018 Copyright Ege Consulting, Inc.
24
Exercise: shopping cart
11/11/2018 Copyright Ege Consulting, Inc.
25
Greeting.html <html><head>
Greeting.jsp: <html> <head> <title>Shopping cart example</title> </head> <body> <h1>Welcome to the Mini Store</h1> <form action=" method="post"> Please select one or more of our products:<br> <select name="products" multiple> <option>product 1 <option>product 2 <option>product 3 <option>product 4 <option>product 5 <option>product 6 </select> <input type="submit"> </form> </body> </html> <html><head> <title>Shopping cart example</title></head> <body><h1>Welcome to the Mini Store</h1> <form action="MiniStore.jsp" method="post"> Please select one or more of our products:<br> <select name="products" multiple> <option>product 1 <option>product 2 <option>product 3 <option>product 4 <option>product 5 <option>product 6 </select> <input type="submit"> </form> </body></html> 11/11/2018 Copyright Ege Consulting, Inc.
26
MiniStore.jsp (1/3) <%@ page import="java.util.*" %>
<HTML><BODY> <% if (session.isNew()) { %> <h1>Welcome Newcomer</h1> <% } else { %> <h1>Welcome Back</h1> <% } %> Vector list = (Vector) session.getValue("cart"); if (list == null) list = new Vector(); String products[] = request.getParameterValues("products"); if (products != null) for (int i = 0; i < products.length; i++) list.addElement(products[i]); session.putValue("cart", list); <H2>Thanks for your selection:</H2> <TABLE><TR><TH>Product</TH></TR> Enumeration all = list.elements(); while (all.hasMoreElements()) out.println("<TR><TD>" + all.nextElement() +"</TD>"); </tr></table> <jsp:include page="continue.htm" flush="true" /> </body></html> page import="java.util.*" %> <HTML><BODY> <% if (session.isNew()) { %> <h1>Welcome Newcomer</h1> <% } else { %> <h1>Welcome Back</h1> <% } %> 11/11/2018 Copyright Ege Consulting, Inc.
27
MiniStore.jsp (2/3) <%
page import="java.util.*" %> <HTML><BODY> <% if (session.isNew()) { %> <h1>Welcome Newcomer</h1> <% } else { %> <h1>Welcome Back</h1> <% } %> Vector list = (Vector) session.getValue("cart"); if (list == null) list = new Vector(); String products[] = request.getParameterValues("products"); if (products != null) for (int i = 0; i < products.length; i++) list.addElement(products[i]); session.putValue("cart", list); <H2>Thanks for your selection:</H2> <TABLE><TR><TH>Product</TH></TR> Enumeration all = list.elements(); while (all.hasMoreElements()) out.println("<TR><TD>" + all.nextElement() +"</TD>"); </tr></table> <jsp:include page="continue.htm" flush="true" /> </body></html> <% Vector list = (Vector) session.getAttribute("cart"); if (list == null) list = new Vector(); String products[] = request.getParameterValues("products"); if (products != null) for (int i = 0; i < products.length; i++) list.addElement(products[i]); session.setAttribute("cart", list); %> 11/11/2018 Copyright Ege Consulting, Inc.
28
MiniStore.jsp (3/3) <H2>Thanks for your selection:</H2>
page import="java.util.*" %> <HTML><BODY> <% if (session.isNew()) { %> <h1>Welcome Newcomer</h1> <% } else { %> <h1>Welcome Back</h1> <% } %> Vector list = (Vector) session.getValue("cart"); if (list == null) list = new Vector(); String products[] = request.getParameterValues("products"); if (products != null) for (int i = 0; i < products.length; i++) list.addElement(products[i]); session.putValue("cart", list); <H2>Thanks for your selection:</H2> <TABLE><TR><TH>Product</TH></TR> Enumeration all = list.elements(); while (all.hasMoreElements()) out.println("<TR><TD>" + all.nextElement() +"</TD>"); </tr></table> <jsp:include page="continue.htm" flush="true" /> </body></html> <H2>Thanks for your selection:</H2> <TABLE><TR><TH>Product</TH></TR> <% Enumeration all = list.elements(); while (all.hasMoreElements()) out.println("<TR><TD>" + all.nextElement() +"</TD>"); %> </tr></table> <jsp:include page="continue.html"/> </body></html> 11/11/2018 Copyright Ege Consulting, Inc.
29
continue.html <form action="Greeting.html">
<input type="submit" value="Continue Shopping"> </form> <form action="Greeting.html"> <input type="submit" value="Continue Shopping"> </form> 11/11/2018 Copyright Ege Consulting, Inc.
30
jsp:useBean action <jsp:useBean id="name" class="package.class" /> instantiates an object of the specified class binds it to a variable with id “name” variable can be used to invoke bean methods or to handle its properties bean can be associated with scope 11/11/2018 Copyright Ege Consulting, Inc.
31
jsp:useBean action scope attribute
<jsp:useBean id="name" class="package.class" scope=“value”/> values can be page (default) request session application makes bean accessible within scope 11/11/2018
32
jsp:setProperty action
<jsp:setProperty name="orderBean" property="numberOfItems" value=“21" /> param="numItems" /> sets value of bean property 11/11/2018
33
jsp:getProperty action
<jsp:getProperty name="itemBean" property="numItems" /> value of bean property is returned 11/11/2018
34
Bean example package jspexamples; public class Counter {
private int value = 0; public int getValue() { return value; } public void setValue(int newValue) { value = newValue; 11/11/2018
35
JSP example <html> <head>
<title>Bean JSP example</title> </head> <body> <jsp:useBean id="counter" class="jspexamples.Counter"/> <jsp:setProperty name="counter" property="value" value="10"/> Current value is <jsp:getProperty name="counter" property="value"/> </body></html> 11/11/2018
36
Variation in scope <jsp:useBean id=“counter"
request make bean accessible via the request variable request is shared in “forward” or “include” JSP example <jsp:useBean id=“counter" class=“jspexamples.Counter" scope=“request”/> 11/11/2018
37
Variation in scope <jsp:useBean …> action other scopes
will find existing bean within scope other scopes session application available to all servlets within the same ServletContext 11/11/2018
38
Jsp example (1/2) <html><head>
<title>Bean JSP example</title> </head><body> <jsp:useBean id="counter" class="jspexamples.Counter” scope="request"/> <jsp:setProperty name="counter“ property="value" value="10"/> <jsp:forward page="BeanTest2.jsp"/> </body></html> 11/11/2018
39
Jsp example (2/2): BeanTest2.jsp
<html><head> <title>Bean JSP example</title> </head><body> <jsp:useBean id="counter" class="jspexamples.Counter“ scope="request"/> Value is now: <jsp:getProperty name="counter" property="value"/> </body></html> 11/11/2018
40
Advanced Exercise create Shopping cart bean share with session scope
11/11/2018
41
ShoppingCart bean package mypackage; import java.util.*;
public class ShoppingCart { private Vector<String> products = new Vector<String>(); public String getTable() { StringBuffer buf = new StringBuffer(); Enumeration all = products.elements(); while (all.hasMoreElements()) buf.append("<TR><TD>" + all.nextElement() + "</TD>"); return buf.toString(); } public void setAddOns(String[] addOns) { for (int i = 0; i < addOns.length; i++) products.addElement(addOns[i]); 11/11/2018
42
MiniBeans.jsp <HTML><BODY>
<H2>Thank you for your selection</H2> <jsp:useBean id="cart" class=“mypackage.ShoppingCart" scope="session"/> <jsp:setProperty name="cart" property="addOns" param="products"/> <TABLE><TR><TH>Content of Shopping Cart:</TH></TR> <jsp:getProperty name="cart" property="Table"/> </TR></TABLE> <jsp:include page="continue.html" /> </BODY></HTML> 11/11/2018
Similar presentations
