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Server-Side Scripting with Java Server Page, JSP
ISYS 350
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Java Website Java Tutorial: JSP, Servlet tutorial:
JSP, Servlet tutorial:
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Java Platforms Java SE (Standard Edition) provides the core functionality of the Java programming language. It defines everything from the basic types and objects of the Java programming language to high-level classes that are used for networking, security, database access, etc. Java EE (Enterprise Edition) is built on top of the Java SE platform for developing and running large-scale, multi-tiered, scalable, reliable, and secure network applications. Java ME (Mobile Edition) provides an API and a small-footprint virtual machine for running Java programming language applications on small devices, like mobile phones.
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Using Java Classes To develop Java applications, we need to use many different Java classes. Groups of related Java classes are organized into packages. To use a class from a package we use the “import” statement to import the class.
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Hyper Text Transfer Protocol: Request & Response
HTTP Request Browser Web Server HTTP Response Web Application
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Data Sent with Request and Response
requested URL, cookies, queryString, data from a form, etc. Response: Web page content in HTML code Cookies Etc.
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Java Server Pages, JSP Java Server Pages (JSP) is a technology that lets you mix regular, static HTML with dynamically-generated HTMLrequest: JSP objects: Request object: retrieves the values that the client browser passed to the server during an HTTP request Response object: This denotes the HTTP Response data. Session: This denotes the data associated with a specific session of user. The main use of Session Objects is for maintaining states when there are multiple page requests. Out object: print, println
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Methods of request Object
getParameter(String name): Returns the value of a request parameter as a String, or null if the parameter does not exist. getQueryString(): Gets any query string that is part of the HTTP request URI. getCookies(): Gets the array of cookies found in this request. getRequestURI(): Gets the URI to the current JSP page. etc.
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Methods of response Object
addCookie(Cookie): Adds the specified cookie to the response. It can be called multiple times to set more than one cookie. sendRedirect(String): Sends a temporary redirect response to the client using the specified redirect location URL.
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JSP Out Object println: The println method of out object is used to write the value to the output, including the newline character. Ex. out.println("The Output is:" + ex); print: The print method of out object writes the value to the output without a newline character. out.print("Welcome!!!"); out.print("To JSP Training"); Output is: Welcome!!! To JSP Training
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Use JSP to Process a Form
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FORM Button: Form attribute: Type = “submit” Method:
Preferred method is: Post Action: Specify the URL of a program on a server or an address to which a form’s data will be submitted. Method: Post/Get <form name="testForm" method="post" action="computeSum.jsp“> Button: Type = “submit” <input type="submit" value="ComputeSumJSP" name="btnCompute"/>
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Compute the Sum of 2 Numbers:
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Form Example <body>
<div>Compute the sum of two numbers</div> <form name="testForm" method="post" action="computeSum.jsp"> Enter num1: <input type="text" name="num1" value="" /><br> Enter num2: <input type="text" name="num2" value="" /><br><br> <input type="submit" value="ComputeSumJSP" name="btnCompute"/> </form> </body>
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Example of JSP scriptlet <% %> Compute the Sum of 2 Numbers:
<body> <% String value1, value2; double n1, n2, sum; value1=request.getParameter("num1"); value2=request.getParameter("num2"); n1= Double.parseDouble(value1); n2= Double.parseDouble(value2); sum=n1+n2; out.println("The sum is:" + sum); %> </body> Note 1: Double is an object that offers the parseDouble method, not “double” data type. Note 2: “out” is an implicit object that does not need to be declared. It is already predefined .
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Writing HTML code as output
<body> <% String value1, value2; double n1, n2, sum; value1=request.getParameter("num1"); value2=request.getParameter("num2"); n1= Double.parseDouble(value1); n2= Double.parseDouble(value2); sum=n1+n2; out.println(" <p>Value1: <input type=‘text' name='num1' size='20' value='" + value1 + "'></p>"); out.println(" <p>Value2: <input type='text' name='num2' size='20' value='" + value2 + "'></p>"); out.println("The sum is: <input type='text' name='sum' size='20' value='" + sum + "'>" ); %> </body>
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Embed JSP code in HTML Using JSP Expression: <%= %>
String value1, value2; double n1, n2, sum; value1=request.getParameter("num1"); value2=request.getParameter("num2"); n1= Double.parseDouble(value1); n2= Double.parseDouble(value2); sum=n1+n2; %> <form method="POST" name="testForm" > <p>Value1: <input type="text" name="num1" size="20" value="<%=value1%>"></p> <p>Value2: <input type="text" name="num2" size="20" value="<%=value2%>"></p> <p> Sum is: <input type="text" name="num2" size="20" value="<%=sum%>"></p> </form>
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Import Java Class Example: Display Current Date Time
Import java.util.Date import="java.util.Date"%> Define a Date type variable: Date currentDate = new Date(); Display in textbox using JSP expression: <p>The time is: <input type="text" name="num2" size="20" value="<%=currentDate%>"></p>
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Compute Future Value: Process form with various controls
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Form Code <form name="fvForm" method="post" action="computeFV.jsp"> Enter present value: <input type="text" name="PV" value="" /><br><br> Select interest rate: <select name="Rate"> <option value=.04>4%</option> <option value=.05>5%</option> <option value=.06>6%</option> <option value=.07>7%</option> <option value=.08>8%</option> </select><br><br> Select year: <br> <input type="radio" name="Year" value="10" />10-year<br> <input type="radio" name="Year" value="15" />15-year<br> <input type="radio" name="Year" value="30" />30-year<br><br> <input type="submit" value="ComputeFVJSP" name="btnCompute" /> </form>
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JSP Code Example <body> <% String myPV, myRate, myYear;
myPV=request.getParameter("PV"); myRate=request.getParameter("Rate"); myYear=request.getParameter("Year"); double FV, PV, Rate, Year; PV=Double.parseDouble(myPV); Rate=Double.parseDouble(myRate); Year=Double.parseDouble(myYear); FV=PV*Math.pow(1+Rate,Year); out.println("FutureValue is:"+ FV); %>
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Use Client-Side Validating and Sumbit Validated Form
<script type="text/javascript"> <!-- function Validating(){ var Valid; Valid=true; if (document.fvForm.PV.value=="") {Valid=false;} if (Valid==false){alert("Cannot contain blank");} else {document.fvForm.submit();} } --> </script> Note: Must use a standard button, not submit button: <input type="button" value="ComputeFVJSP" name="btnCompute" onclick="Validating()"/>
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Depreciation Table Straight Line Depreciation Table
<form name="depForm" method="post" action="createDepTable.jsp"> Enter Property Value: <input type="text" name="pValue" value="" /><br> Enter Property Life: <input type="text" name="pLife" value="" /><br> <input type="submit" value="ShowTable JSP" name="btnShowTable" /> </form>
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Output
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<% String strValue, strLife; strValue=request.getParameter("pValue"); strLife=request.getParameter("pLife"); double value, life, depreciation,totalDepreciation=0; value=Double.parseDouble(strValue); life=Double.parseDouble(strLife); NumberFormat nf = NumberFormat.getCurrencyInstance(); out.println("Straight Line Depreciation Table" + "<br>"); out.println("Property Value: <input type='text' name='pValue' value='" + nf.format(value) + "' /><br>"); out.println("Property Life: <input type='text' name='pLife' value='" + life + "' /><br>"); depreciation=value/life; totalDepreciation=depreciation; out.println( "<table border='1' width='400' cellspacing=1>"); out.println("<thead> <tr> <th>Year</th> <th>Value at BeginYr</th>"); out.println("<th>Dep During Yr</th> <th>Total to EndOfYr</th></tr> </thead>"); out.println("<tbody>"); for (int count = 1; count <= life; count++) { out.write("<tr>"); out.write(" <td width='25%'>" + count + "</td>"); out.write(" <td width='25%'>" + nf.format(value) + "</td>"); out.write(" <td width='25%'>" + nf.format(depreciation) + "</td>"); out.write(" <td width='25%'>" + nf.format(totalDepreciation) + "</td>"); value -= depreciation; totalDepreciation+=depreciation; } %>
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Number to Currency Format
Import class: import="java.text.NumberFormat"%> Define a format: NumberFormat nf = NumberFormat.getCurrencyInstance(); Convert: Example: Display payment with currency format: nf.format(payment)
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Using JSP Expression <body> <% String strValue, strLife;
strValue=request.getParameter("pValue"); strLife=request.getParameter("pLife"); double value, life, depreciation,totalDepreciation=0; value=Double.parseDouble(strValue); life=Double.parseDouble(strLife); NumberFormat nf = NumberFormat.getCurrencyInstance(); depreciation=value/life; totalDepreciation=depreciation; %> <p>Straight Line Depreciation Table</p> <p>Property Value: <input type='text' name='pValue' value='<%=nf.format(value)%>' /></p> <p>Property Life: <input type='text' name='pLife' value='<%=life%>'/></p> <table border='1' width='400' cellspacing=1> <thead> <tr> <th>Year</th> <th>Value at BeginYr</th> <th>Dep During Yr</th> <th>Total to EndOfYr</th> </tr> </thead> <tbody> for (int count = 1; count <= life; count++) { <tr> <td width='25%'><%=count%></td> <td width='25%'><%=nf.format(value)%></td> <td width='25%'><%=nf.format(depreciation)%></td> <td width='25%'><%=nf.format(totalDepreciation)%></td> value -= depreciation; totalDepreciation+=depreciation; } </table> </body>
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Cookie Cookie is a small data file added by a website to reside in user’s system. Define a cookie: new Cookie(“Key”, “value”); Ex. Cookie cookieCID = new Cookie ("cookieCID",CID); Write a cookie: response.addCookie(cookieCID);
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Example: <% String CID, Cname; CID=request.getParameter("CID");
Cname=request.getParameter("Cname"); Cookie cookieCID = new Cookie ("cookieCID",CID); response.addCookie(cookieCID); Cookie cookieCname = new Cookie ("cookieCname",Cname); response.addCookie(cookieCname); out.println("CID cookie= " + CID + "added"); out.println("Cname cookie= " + Cname + "added"); %> Note: To view cookies with FireFox:Tools/Options/Privacy
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Reading Cookies Use request.getCookies() method.
This method retrieve cookies and return them in an array. <% Cookie[] cookies = request.getCookies(); out.println(cookies[0].getName() + cookies[0].getValue() + "<br>"); out.println(cookies[1].getName() + cookies[1].getValue() + "<br>"); %>
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Expire a cookie Add a expiration time: cookieCID setMaxAge(N);
N is # of seconds N = 0, the cookie will be deleted right way N < 0 : the cookie will be deleted once the user exit the browser Cookie cookieCID = new Cookie ("cookieCID",CID); cookieCID.setMaxAge(-1);
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JSP Session Object Session Object denotes the data associated with a specific session of user. Methods: session.setAttribute(“Key”, object) add an object to the session object associated with a key. session.getId() return the unique identifier associated with the session session.getAttribute(“key”) return the object with the specified key given in parameter
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Add an object to session object Add Cname to session, then redirect to another page to read the cname <% Cookie[] cookies = request.getCookies(); out.println(cookies[0].getName() + cookies[0].getValue() + "<br>"); out.println(cookies[1].getName() + cookies[1].getValue() + "<br>"); session.setAttribute("Cname", cookies[1].getValue()); response.sendRedirect("readSession.jsp"); %>
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Retrieve an object from session
<% Object custName; custName=session.getAttribute("Cname"); out.println("Welcome, " + custName.toString()); %>
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