stanisław osiński, 2002jsp – a technology for serving dynamic web content java server pages™ a...

JSP – A technology for serving dynamic web content Stanisław Osiński, 2002

Java Server Pages™

A technology for serving dynamic web content

Stanisław Osiński, [email protected]

What is JSP ?

Elements of a JSP document

JavaBeans and JSP

TagLibs, JSTL

JSP and Java Servlets

JSP v2.0

Summary

Internet Applications, Lecture 4


Agenda

• What is JSP ?• Elements of a JSP document• JavaBeans and JSP• Exception handling• Custom Tags, JSP Standard Tag

Library• JSP and Java Servlets• JSP v2.0 – new features• Summary

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


What is JSP ?

„The JavaServer Pages technology provides the means for textual specification of the creation of a dynamic response to a request”

(JSP Spec. v1.2)

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

What is JSP ?

JSP is a textual specification of the creation of a dynamic response to a request (JSP Spec. v1.2)

/** */public class SomeServlet extends HttpServlet { /** */ protected void doGet(...) { // ... out.println(„<HTML><TITLE>Title</TITLE>”); out.println(„<BODY>Today is:”);

out.println(new java.util.Date().toString());

out.println(„</BODY>”); out.println(„</HTML>”);

out.close(); }}

/** */public class SomeServlet extends HttpServlet { /** */ protected void doGet(...) { // ... out.println(„<HTML><TITLE>Title</TITLE>”); out.println(„<BODY>Today is:”);

out.println(new java.util.Date().toString());

out.println(„</BODY>”); out.println(„</HTML>”);

out.close(); }}

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

What is JSP ?

<HTML> <TITLE>Title</TITLE>; <BODY> Today is:

<%= new java.util.Date().toString() %>

 </BODY></HTML>

<HTML> <TITLE>Title</TITLE>; <BODY> Today is:

<%= new java.util.Date().toString() %>

 </BODY></HTML>

JSP is a textual specification of the creation of a dynamic response to a request (JSP Spec. v1.2)

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

<%-- An example JSP page --%>

<%@page import=„java.util.*" contentType="text/html" session="true" %>

<HTML> <TITLE>Title</TITLE> <BODY> Today is:

<%! String date; %>

<% date = new Date().toString(); %>

<%= date %> 

<jsp:include page="logo.jsp"/> </BODY></HTML>

<%-- An example JSP page --%>

<%@page import=„java.util.*" contentType="text/html" session="true" %>

<HTML> <TITLE>Title</TITLE> <BODY> Today is:

<%! String date; %>

<% date = new Date().toString(); %>

<%= date %> 

<jsp:include page="logo.jsp"/> </BODY></HTML>

Directivespage – JSP document

properties

Static content written verbatim to

the output document

Declarations of global variables and methods

Java code ("scriptlets") executed on request time

Expressions evaluated on request

timeActions executed on

request time

Comment not copied to the output document

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


Implicit Objects

In every JSP document a number of implicit objects can be accessed:

• application (javax.servlet.ServletContext)• config (javax.servlet.ServletConfig)• out (javax.servlet.jsp.JspWriter)• request (javax.servlet.ServletRequest)• response (java.servlet.ServletResponse)• session (javax.servlet.http.HttpSession)• exception (java.lang.Throwable)

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


JavaBeans in JSP (1)

package org.stachoodev.examples.*;

/** */public class Login { /** */ private String userId, password;

/** */ public void setUserId(String userId) { this.userId = userId; }

/** */ public void setPassword(String password) { this.password = password; }

/** */ public boolean isLoginCorrect() { return userId.equals(password); }}

package org.stachoodev.examples.*;

/** */public class Login { /** */ private String userId, password;

/** */ public void setUserId(String userId) { this.userId = userId; }

/** */ public void setPassword(String password) { this.password = password; }

/** */ public boolean isLoginCorrect() { return userId.equals(password); }}

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

<%@page import="org.stachoodev.examples.*" contentType="text/html" %>

<HTML> <TITLE>Login</TITLE> <BODY> <% Login login = new Login(); login.setUserId(request.getParameter("userId”)); login.setPassword(request.getParameter("password”)); %>

<% if (login.isLoginCorrect()) { %> Login successful. <% } else { %> Login failed. <% } %>

 </BODY></HTML>


<HTML> <TITLE>Login</TITLE> <BODY> <% Login login = new Login(); login.setUserId(request.getParameter("userId”)); login.setPassword(request.getParameter("password”)); %>

<% if (login.isLoginCorrect()) { %> Login successful. <% } else { %> Login failed. <% } %>

 </BODY></HTML>

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

<jsp:useBean id="login" scope="page" class="Login"/>

<HTML> <TITLE>Login</TITLE> <BODY> <% login.setUserId(request.getParameter("userId")); login.setPassword(request.getParameter("password")); %>

<% if (login.isLoginCorrect()) { %> Login successful. <% } else { %> Login failed. <% } %> </BODY></HTML>


<jsp:useBean id="login" scope="page" class="Login"/>

<HTML> <TITLE>Login</TITLE> <BODY> <% login.setUserId(request.getParameter("userId")); login.setPassword(request.getParameter("password")); %>

<% if (login.isLoginCorrect()) { %> Login successful. <% } else { %> Login failed. <% } %> </BODY></HTML>

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


JavaBean instance scope

The scope parameter of the jsp:useBean action determines the "visibility" of a JavaBean instance:

• page – the bean is visible only within the JSP page containing its declaration• request – the bean is visible in any JSP page processing the same request• session – the instance is accessible across the current user session• application – any JSP page can access the JavaBean instance

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

<jsp:useBean id="login" scope="page" class="Login" />

<jsp:setProperty name="login" property="userId" value="<%= request.getParameter("userId") %>" /><jsp:setProperty name="login" property="passowrd" value="<%= request.getParameter("password") %>" />

<HTML> <TITLE>Login</TITLE> <BODY> <% if (login.isLoginCorrect()) { %> Login successful. <% } else { %> Login failed. <% } %> </BODY></HTML>



<jsp:setProperty name="login" property="userId" value="<%= request.getParameter("userId") %>" /><jsp:setProperty name="login" property="passowrd" value="<%= request.getParameter("password") %>" />


What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

<jsp:setProperty name="login" property="*" />






What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

Exception handling

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

<%@page contentType="text/html" errorPage="error.jsp" %>

<HTML> <TITLE>Test page</TITLE> <BODY> <% ((String)null).length(); %> </BODY></HTML>

<%@page contentType="text/html" errorPage="error.jsp" %>

<HTML> <TITLE>Test page</TITLE> <BODY> <% ((String)null).length(); %> </BODY></HTML>

<%@page contentType="text/html" isErrorPage="true" %>

<HTML> <TITLE>Error</TITLE> <BODY> An error has occurred: <%= exception.getMessage() %> </BODY></HTML>

<%@page contentType="text/html" isErrorPage="true" %>

<HTML> <TITLE>Error</TITLE> <BODY> An error has occurred: <%= exception.getMessage() %> </BODY></HTML>

error.jsp

Including and forwarding




<%@include file="page_header.html" %>

<% if (login.isLoginCorrect()) { %>

<jsp:forward page="welcome.jsp" />

<% } else { %>

<jsp:include page="forgotten.jsp" />

<% } %>

<%@include file="page_footer.html" %>





<% if (login.isLoginCorrect()) { %>

<jsp:forward page="welcome.jsp" />

<% } else { %>

<jsp:include page="forgotten.jsp" />

<% } %>


What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

Custom Tags (1)


<%@taglib prefix="util" uri="util.tld" %>


<util:login request="<%= request %>" />



<%@taglib prefix="util" uri="util.tld" %>


<util:login request="<%= request %>" />


What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


Custom Tags (2)

To implement a Custom JSP Tag:

• Create the tag handler class (doStartTag(), doEndTag(), ...)• Create the class describing the variables accesible within the Custom Tag (optional)• Create the Tag Library Descriptor (TLD file)

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


JSP Standard Tag Library

A standardized library of JSP Custom Tags:

• conditions, loops, enumerations• URL transformations• content localization• formatting of numbers and dates• SQL queries• XML processing• XSLT transformations• validation of JSP documents

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

<%@page import="java.util.*" %><HTML> <TITLE>Title</TITLE>; <BODY> Today is:

<%= new Date().toString() %>

 </BODY></HTML>

<%@page import="java.util.*" %><HTML> <TITLE>Title</TITLE>; <BODY> Today is:

<%= new Date().toString() %>

 </BODY></HTML>

User Agent (IE, Netscape, ...)JSP Container

generation + compilation

execution

HTTP request

Java Servlet

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

<%@page import=„java.util.*" %>

<HTML> <TITLE>JSP test</TITLE> <BODY> <%! String date; %> <% date = new Date().toString(); %> Today is: <%= date %> </BODY></HTML>

<%@page import=„java.util.*" %>

<HTML> <TITLE>JSP test</TITLE> <BODY> <%! String date; %> <% date = new Date().toString(); %> Today is: <%= date %> </BODY></HTML>


package org.apache.jsp;

import java.util.*;import javax.servlet.*;// ...

public class test$jsp extends HttpJspBase {

// begin [file="/test.jsp";from=(8,9);to=(8,23)] String date; // end

public void _jspService(...) { // ... session = pageContext.getSession();

// HTML [file="/test.jsp";from=(2,36);to=(8,6)] out.write("\r\n\r\n<HTML>\r\n<TITLE>JSP..."); // end

// begin [file="/test.jsp";from=(9,8);to=(11,6)] date = new Date().toString(); // end

// begin [file="/test.jsp";from=(14,9);to=(14,15)] out.print( date ); // end }}

package org.apache.jsp;

import java.util.*;import javax.servlet.*;// ...

public class test$jsp extends HttpJspBase {

// begin [file="/test.jsp";from=(8,9);to=(8,23)] String date; // end

public void _jspService(...) { // ... session = pageContext.getSession();

// HTML [file="/test.jsp";from=(2,36);to=(8,6)] out.write("\r\n\r\n<HTML>\r\n<TITLE>JSP..."); // end

// begin [file="/test.jsp";from=(9,8);to=(11,6)] date = new Date().toString(); // end

// begin [file="/test.jsp";from=(14,9);to=(14,15)] out.print( date ); // end }}

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


JSP Specification v2.0

A lot of changes and improvements:

• Expression Language (EL) – scriptless JSP• Tag Files• based on Servlet Specification v2.4 • requires Java 2 Platform v1.4• to be implemented in Tomcat 5.0

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


Summary

JSP vs. Java Servlets:

• better, though still imperfect, code-content separation

• Tag Libraries - extensibility and component reuse

• faster development (less typing ;)• development tools available

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


Summary

JavaServer Pages Homehttp://java.sun.com/jsp/

JSP Standard Templates Libraryhttp://java.sun.com/products/jsp/jstl/

Tomcat – Reference Implementation

http://jakarta.apache.org/tomcat

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary


Java Server PagesA technology for serving dynamic web content

Stanisław Osiński, [email protected]

Thank you for your attention

What is JSP ?


JavaBeans and JSP

Exception handling

TagLibs, JSTL


JSP v2.0

Summary

stanisław osiński, 2002jsp – a technology for serving dynamic web content java server pages™ a...

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