I Feel Pretty
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Boston Computing Review 2007
Boston Computing ReviewPragmatic Architectural Overview
Java Server Pages
John Brunswick
Boston Computing Review 2007
• Why? This is so old school.
• History and Pains of Web Development
• Foundation
• Development Tools
• Anatomy
• Nuts and Bolts
• Over the Horizon
Boston Computing Review 2007
Why? It is not sexy.
• Presentation Layer for J2EE• Nobody owns it• It is here and not going anywhere• What do non-Microsoft projects get developed
with? Yup.– Oracle, BEA, IBM, SAP, EMC, HP… and on and on.
• Want to code in the enterprise?– API heaven
• Frameworks– JSF and others
Boston Computing Review 2007
HistoryStep into the time machine
Boston Computing Review 2007
Common Gateway Interface (CGI)
• CGI is not a programming language
• Most CGI programs are written in Perl
• Issues– Scalability– Security– Debugging– Seperation of Presentation and Logic
Boston Computing Review 2007
Classic ASP (3.0)
• Single platform (MS)
• Mixed presentation and logic
• Run time interpretation
Boston Computing Review 2007
Hypertext Preprocessor (PHP)
• Lacks OO Design
• Runtime interpretation
• Mixed presentation and logic
Boston Computing Review 2007
Coldfusion Markup Language (CFM)• Depth
• Scalability
• Enterprise Interoperability
Boston Computing Review 2007
ASP.NET
• Platform (MS)
• Lacks MVC
• Cost
Boston Computing Review 2007
Emerging Web Application Frameworks• ROR
• Django
Boston Computing Review 2007
Digging In
Boston Computing Review 2007
Foundation Overview
• JSP is actually servlets!
• Application / HTTP Server
• Acronym Overload
• How do we develop?
• Application Anatomy 101
• JDBC
Boston Computing Review 2007
Servlet JSP• HelloWorld Servlet• package org.apache.jsp;• import javax.servlet.*;• import javax.servlet.http.*;• import javax.servlet.jsp.*;• public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase• implements org.apache.jasper.runtime.JspSourceDependent {• private static java.util.Vector _jspx_dependants;• public java.util.List getDependants() {• return _jspx_dependants;• }• public void _jspService(HttpServletRequest request, HttpServletResponse response)• throws java.io.IOException, ServletException {• JspFactory _jspxFactory = null;• PageContext pageContext = null;• HttpSession session = null;• ServletContext application = null;• ServletConfig config = null;• JspWriter out = null;• Object page = this;• JspWriter _jspx_out = null;• PageContext _jspx_page_context = null;• try {• _jspxFactory = JspFactory.getDefaultFactory();• response.setContentType("text/html");• pageContext = _jspxFactory.getPageContext(this, request, response,• null, true, 8192, true);• _jspx_page_context = pageContext;• application = pageContext.getServletContext();• config = pageContext.getServletConfig();• session = pageContext.getSession();• out = pageContext.getOut();• _jspx_out = out;• out.write("<html>\n");• out.write(" <head>\n");• out.write(" <title>JSP and Beyond Hello World</title>\n");• out.write(" </head>\n");• out.write(" <body>\n");• out.write(" Hello World \n");• out.write(" </body>\n");• out.write("</html>\n");• } catch (Throwable t) {• if (!(t instanceof SkipPageException)){• out = _jspx_out;• if (out != null && out.getBufferSize() != 0)• out.clearBuffer();• if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);• }• } finally {• if (_jspxFactory != null) _jspxFactory.releasePageContext(_jspx_page_context);• }• }• }
• <html>• <head>• <title>JSP and Beyond Hello World</title>• </head>• <body>• Hello World • </body>• </html>
Boston Computing Review 2007
Server Architecture (container)
Boston Computing Review 2007
Application Servers
• Tomcat– Apache who?
• JBOSS
• Resin
• BEA WebLogic
• WebSphere
• JRUN… (not so much)
Boston Computing Review 2007
Hmmm… Acronyms Abound
• JDK
• J2SE
• SDK
• JRE
• J2EE
• Java 5
• JVM
Boston Computing Review 2007
Start Coding
• Netbeans
• Eclipse
Boston Computing Review 2007
Anatomy 101• YourWebApp/
– Within this directory all static content should reside. This includes JSP, HTML and image files.
• YourWebApp /WEB-INF/– The Web Application deployment descriptor (web.xml) lives within this directory. This
deployment descriptor maintains all of your application settings that dictate how the container delivers your application. This directory is private and not externally accessible by end users.
• YourWebApp /WEB-INF/classes– Java classes and servlets should reside in this directory. This directory is private and not
externally accessible by end users.
• YourWebApp /WEB-INF/lib– Place JAR file and tag libraries here. This directory is private and not externally accessible
by end users.
FYI…. During application development it is most advantageous to work with your application files in what is called an exploded format. Once the application is ready for distribution it can be packaged into a WAR file for easy portability.
Boston Computing Review 2007
WARs JARs and EARs?
• WAR– One big zip file for an application, no fighting!
• JAR– Zip file with classes
• EAR– Lots of WARs, JARs– For Enterprise (not Kirk and Spock)
Boston Computing Review 2007
JSP Dissected
Boston Computing Review 2007
Page Elements
Boston Computing Review 2007
Scriptlet <% … %>
• Inline Code (yuck)<table> <% String months[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "July", "Aug", "Sep", "Oct", "Nov", "Dec"}; for(int i = 0; i < months.length; i++ ) { %> <tr> <td> Month: <%= months[i] %> </td> </tr> <% } %></table>
Boston Computing Review 2007
Directives <%@ … %>
• Directives do not send output to the screen, but set configuration values for the JSP page
• Page– <%@ page import="java.util.*, java.lang.*" %> – errorPage / isErrorPage– Buffering… etc…
• Include Directive• Taglib Directive• http://java.sun.com/products/jsp/syntax/1.2/synta
xref1210.html.
Boston Computing Review 2007
Expression <%= … %>
<%@ page import="java.util.*" %><%! String sName = "Bill Smith"; %><table> <tr> <td> Welcome <%= sName %>! </td> </tr></table>
• Straight to screen output
Boston Computing Review 2007
Decleration <%! … %>
• Used to set variables and define methods within the JSP <%@ page import="java.util.*" %>
<%!// This is the method that will return the current timeString GetCurrentTime(){
Date date = new Date();return date.toString();
}%><table><tr><td>What time is it? <%= GetCurrentTime() %></td></tr></table>
Boston Computing Review 2007
Comment <%-- … --%>
• With the JSP style comments we can keep comments inline with the code, but they will not be sent to the requestor’s browser.
Boston Computing Review 2007
Programming Elements
Boston Computing Review 2007
Implicit Objects
• Request– Cookies, querystring variables and other pieces of data are
readily accessible from the request object.
• Response– Response is used to send information to the client. A good
example might be setting a cookie. The following block of code send a cookie to the client that can be retrieved at a later time <% response.addCookie(myCookie) %>
• Session– The session object is useful for storing small amounts of
information that will be accessible throughout a users visit to your application or web site. A good example might be their user ID so you will not have to continually query a database to find this information
• Etc…..
Boston Computing Review 2007
Coffee Time - JavaBeans
• Provide a simple interface for storing, retrieving information and other complex operations through a very simple XML tag
• By using this level of integration with JSP JavaBeans can help us to separate the presentation (HTML) from the business logic that the Beans handle
• Value VS Utility• Reuse• Reuse
Boston Computing Review 2007
Get and Set (encapsulate)public class OurSampleBean{
String sOurTestValue;public OurSampleBean() {}
public String getSometValue(){
Return someValue;}public void setSomeValue (String sSomeValue){
this.value = sSomeValue;}
}
Boston Computing Review 2007
JDBC – Get our DB on
// Import the namespace for the database connection
import java.sql// Create the database connection objectConnection cnDB = null;// Load the driver that will be used for the database connection
Class.forName("com.mysql.jdbc.Driver").newInstance();
// Establish the connectioncnDB = DriverManager.getConnection("jdbc:mysql:///DatabaseName","user", "password");
Boston Computing Review 2007
JDBC Cont…
// Prepare a statement object that will be used to request the data
Statement stmt = cnDB.createStatement(); // Create an object to hold the results setResultSet results;// Populate the results object with the data from the SQL statement above
results = stmt.executeQuery("SELECT * FROM tblCustomer ORDER BY CustomerName");
Boston Computing Review 2007
One more for the road
// Obtain a statement objectStatement stmt = cnDB.createStatement();
// Execute the block of SQL codestmt.executeUpdate("INSERT INTO tblCustomer VALUES ('Smith', 'Boston', 2006)");
// Close the result setstmt.close();// Close the connectioncnDB.close();
Boston Computing Review 2007
JSTL – Messy but fun
• Hmmm… CFM anyone?
• Good for prototyping
<c:if test="${book.orderQuantity > book.inStock}"> The book <c:out value="${book.title}"/> is currently out of stock. </c:if>
Boston Computing Review 2007
And then some…
Boston Computing Review 2007
And then…
• Error handling<%@ page errorPage="CatchError.jsp"%>
<%@ page isErrorPage="true" %>
• Email– Grab a library
• File upload– Use a bean
Boston Computing Review 2007
Next Level
• MVC and Frameworks– JSF, Struts
Boston Computing Review 2007
Thanks for your time!