Introduction to jsp

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Introduction to jsp

  1. 1. Introduction to JSP
  2. 2. JSP and Servlets / Session 5 / 2 of 24 Objectives Explain JSP Identify the advantages of using JSP Describe various elements of JSP Describe the JSP Life Cycle Develop JSP using Java Studio Enterprise 8
  3. 3. JSP and Servlets / Session 5 / 3 of 24 Introduction to JSP Java Server Pages (JSP) are saved with the extension .jsp. Efficiently controls dynamic content generation. Uses Java programming language and class libraries. Uses HTML for presentation of pages and Java code to access dynamic content. JSP page JAVA Server JSP uses JAVA to access dynamic content
  4. 4. JSP and Servlets / Session 5 / 4 of 24 Benefits of JSP 3-1 Separates content from presentation Request Response JSP page Static Content Dynamic Content Server Client Web Designer JSP Programmer
  5. 5. JSP and Servlets / Session 5 / 5 of 24 Benefits of JSP 3-2 Emphasizes reusable components JSP page 1 Static Content Dynamic Content JSP page 2 Static Content Dynamic Content JSP page 3 Static Content Dynamic Content JavaBean Multiple JSP pages use the same JavaBean
  6. 6. JSP and Servlets / Session 5 / 6 of 24 Benefits of JSP 3-3 Simplified page development - Web designer and Web programmer use Web development tools to develop a JSP page. JSP page Static Content Dynamic Content Web Designer JSP Programmer Web Development Tools Macromedia Dreamweaver Java Studio Enterprise 8 .....
  7. 7. JSP and Servlets / Session 5 / 7 of 24 Elements of JSP 2-1 Elements of a JSP page Static Content Directives Expressions Scriptlets JSP Page Taglib: <%@ taglib uri= "tagLibraryURI" prefix= "tagPrefix" %> <%valid Java code block%> <%= Java Expression %> Page : <%@ page ATTRIBUTES %> Include: <%@ include file = " Filename" %> Declarations Actions <%! declaration(s) %> Forward Include Plug-ins Bean tags
  8. 8. JSP and Servlets / Session 5 / 8 of 24 Elements of JSP 2-2 <%@ page language="java" %> <html> … … <h1>Elements of JSP</h1> <p>Today is </p> <page id="clock" class= "calendar.jspCalendar" /> <ul> <li>Day: <%=clock.getDayOfMonth() %> <li>Year: <%=clock.getYear() %> </ul> Page Directive JSP ExpressionStatic Content <% if (Calendar.getInstance().get(Calendar.AM_PM) == Calendar.AM) { %> Good Morning <% } else { %> Good Afternoon <% } %> <%@ include file="copyrightfile.html" %> … … </html> JSP Scriptlet Include Directive
  9. 9. JSP and Servlets / Session 5 / 9 of 24 Static Content Static content is the text written on a Web page. Any text-based format can be used to write static content. A page directive is used to specify the format of content. <html> <%@ page contentType = "text/html" %> <head> <title>Example for static content</title> </head> … //Contains text in specified content type. … </body> </html> HTML tags contain static content
  10. 10. JSP and Servlets / Session 5 / 10 of 24 JSP Directives JSP container uses directives for processing of JSP page. Controls the structure of the Servlet Provides global information about a JSP page Scope of directives is the entire JSP file <html> ... <%@ page language="Java" import= “java.rmi.*, java.util.*" session="true" buffer="12kb" autoFlush="true" info="PageDirective" errorPage="error.jsp" isErrorPage="false" isThreadSafe="true" %> <head> <title>Testing Page Directive</title> </head> <body> <h1>Testing Page Directive</h1> This page is testing Page Directive. </body > … … </html> page Directive Demonstration: Example 1 <html> <head> <title>Testing include directive</title> </head> <body> <h1> Example of directives</h1> <%@ include file ="testFile.html" %> </body> </html> include Directive // testFile.html <html> <body> The JSP <b>"include"</b> directive example. </body> </html> Demonstration: Example 2
  11. 11. JSP and Servlets / Session 5 / 11 of 24 JSP Expression Contains a Java statement Value of Java Statement will be evaluated and inserted into generated Web page. Displays individual variables, or the result of some calculation. <html> <head> <title>Testing Expression directive</title> </head> <body> <h1> Testing Expression directive </h1> <% int i = 2, j=3;%> <% i++;%> <% j=j+i; %> … </body> </html> JSP Expression
  12. 12. JSP and Servlets / Session 5 / 12 of 24 JSP Scriptlet Block of Java code that performs functions which are not supported by tags. Executed during run time <html> <head> <title>Scriptlet of a JSP </title> </head> <body> <h1>Scriptlet of a JSP</h1> <% int k=0; for(int i=0;i<5;i++) { k=k+i; System.out.println(k); } %> ... </body> </html> JSP Scriptlet
  13. 13. JSP and Servlets / Session 5 / 13 of 24 JSP Declaration Used to define variables and methods in a JSP page. Declared variables and methods can then be referenced by other scripting elements on the same page. Used to define single or multiple variables <%! int x = 0, y = 0; private String units = "ft"; %> Declares x and y as integer variables Declares units as a String variable <%! public long fact (long x) { if (x == 0) return 1; else return x * fact(x-1); } %> Declares fact method
  14. 14. JSP and Servlets / Session 5 / 14 of 24 JSP Actions Allows the transfer of control between pages Allows JSP pages to access JavaBeans component objects stored on the server. JSP Actions Forward Include Plug-ins Bean tags
  15. 15. JSP and Servlets / Session 5 / 15 of 24 Forward Action Permanently transfers control from a JSP page to another location. JSP Page 1 Forward Action JSP Page 2 Transfers control to another page
  16. 16. JSP and Servlets / Session 5 / 16 of 24 Include Action 2-1 Inserts the content generated by remote resource in the output of the current JSP page. Temporarily transfers the control to a new page JSP Page 1 Include Action JSP Page 2 Transfers control to another page Transfers control back to the original page
  17. 17. JSP and Servlets / Session 5 / 17 of 24 Include Action 2-2 <%@page contentType="text/html"%> <%@page pageEncoding="UTF-8"%> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>jspactionexample</title> </head> <body bgcolor="#ffffff"> <h1>Jsp actions and declarations</h1> <jsp:include flush="true" page="JspExample.jsp"> <jsp:param name="stringeg" value="String passed using forward directive"/> </jsp:include> </body> </html> Include Action Demonstration: Example 3 <%@page contentType="text/html"%> <%@page pageEncoding="UTF-8"%> <%@page language="java" %> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Declaration, Expression and Actions</title> <%=request.getParameter("stringeg")%> <%! static private char[] vowels ={ 'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'}; String word; public boolean startsWithVowel(String word) { this.word=word; char first = word.charAt(0); for (int i = 0; i < vowels.length; ++i) { if (first == vowels[i]) return true; } return false; } JSP Declarations static private String[] articles = { "a ", "an " }; public String withArticle(String noun) { if (startsWithVowel(noun)) return articles[1] + noun; else return articles[0] + noun; } %> </head> <body bgcolor="#ffffff"> <br /> <b>Starts with a vowel: </b> <%=startsWithVowel("I am a very good Programmer")%> <br/> <b>String entered is: </b> <%=word%> <br /> <b>Article:</b> <%=withArticle("apple")%> <br /> </body> </html> JSP Declarations Demonstration: Example 4
  18. 18. JSP and Servlets / Session 5 / 18 of 24 JSP Plug-ins and Bean Tags JSP Plug-ins - Used to generate browser-specific HTML. JSP Bean Tags – Used to interact with JavaBeans stored on the server.
  19. 19. JSP and Servlets / Session 5 / 19 of 24 JSP Life Cycle 3-1 Client JSP page 3 Execution 2 Translation Compilation 1 Servlet Request Server Request ResponseResponse JSP Life Cycle
  20. 20. JSP and Servlets / Session 5 / 20 of 24 JSP Life Cycle 3-2 Translation and Compilation Translation Compilation Servlet JSP Determines Errors in JSP Extracts data from JSP element Generates a Servlet for JSP
  21. 21. JSP and Servlets / Session 5 / 21 of 24 JSP Life Cycle 3-3 Execution – Actions performed during execution are: <%@ page buffer = "none|20kb" %> <%@ page errorPage = "errorJSP.html" %> Handling Errors Sets buffer size Specifies error page Buffering Output
  22. 22. JSP and Servlets / Session 5 / 22 of 24 Demonstration: Example 5 <%@page contentType="text/html"%> <%@page pageEncoding="UTF-8"%> <%! double radius=6.0; private double getRadius(){ return radius; } private double getDiameter(){ return (radius * 2); } private double getArea(){ return (3.1415 * radius); } private double getCircumference(){ return(3.1415 *(radius * 2)); } %> JSP declarations JSP Application in Java Studio Enterprise 8 <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Declaration Tag - Methods</title> </head> <h3>Calculating area and circumference of a Circle</h3> <hr/> <b>Radius of circle:</b> <%=radius%> cm<br/> <b>Diameter:</b> <%=getDiameter()%> cm<br/> <b>Area of Circle is:</b> <%=getArea()%> cm<sup>2</sup><br/> <b>Circumference of a circle is:</b> <%=getCircumference()%><br/> <hr/> <body></body> </html> JSP scriptlets
  23. 23. JSP and Servlets / Session 5 / 23 of 24 Summary  JSP uses Java programming language and class libraries.  JSP page uses HTML to display static text and Java code to generate dynamic content.  Elements of JSP page are static content, JSP directives, JSP expressions, and JSP scriptlets.  A JSP page can be created using standard development tools.  JSP uses reusable and cross-platform components, such as JavaBeans.  JSP allows the creation of user-defined tags and makes the JSP development process easy.  Different phases in JSP life cycle are translation, compilation, and execution.

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