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Server-Side Scripting with Java Server Page, JSP

Server-Side Scripting with Java Server Page, JSP. ISYS 350. Java Website. Java Tutorial: http://docs.oracle.com/javase/tutorial/ JSP, Servlet tutorial: http://www.apl.jhu.edu/~hall/java/Servlet-Tutorial/. Java Platforms.

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Server-Side Scripting with Java Server Page, JSP

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  1. Server-Side Scripting with Java Server Page, JSP ISYS 350

  2. Java Website • Java Tutorial: • http://docs.oracle.com/javase/tutorial/ • JSP, Servlet tutorial: • http://www.apl.jhu.edu/~hall/java/Servlet-Tutorial/

  3. 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.

  4. 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.

  5. Hyper Text Transfer Protocol: Request & Response HTTP Request Browser Web Server HTTP Response Web Application

  6. Data Sent with Request and Response • Request: • requested URL, cookies, queryString, data from a form, etc. • Response: • Web page content in HTML code • Cookies • Etc.

  7. JSP Implicit Objects • Implicit Objects in JSP are objects that are automatically available in JSP. Implicit Objects are Java objects that the JSP Container provides to a developer to access them in their program. • request: The request object retrieves the values that the client browser passed to the server during an HTTP request • response: 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

  8. Methods of request Objecthttp://gulland.com/courses/jsp/objects • 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.

  9. 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.

  10. JSP Out Object • clearBuffer: The clearBuffer method of out object is used to clear the output buffer. • 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

  11. Use JSP to Process a Form

  12. FORM • Form attribute: • Method: • Preferred method is: Post • Action: Specify the URL of a program on a server or an email 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"/>

  13. Compute the Sum of 2 Numbers:

  14. 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>

  15. 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, not “double” data type. Note 2: “out” is an implicit object that does not need to be declared.  It is already predefined .

  16. 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>

  17. Using JSP Expression:return a string, <%= %> 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" action="ComputeSum2.jsp"> <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>

  18. Import Java ClassExample: Display Current Date Time • Import java.util.Date • %@page import="java.util.Date"% • Define a Date type variable: • Date now = new Date(); • Display in textbox using JSP expression: <p>The time is: <input type="text" name="num2" size="20" value="<%=now%>"></p>

  19. Compute Future Value:Process form with various controls

  20. 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>

  21. 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); %>

  22. Using the get method • Querystring: • http://localhost:8080/DemoM262/computeFVget.jsp?PV=1000&Rate=.04&Year=10&btnCompute=ComputeFVJSP • Code: String qString; qString=request.getQueryString(); out.println(qString);

  23. Use the same getParameter() method to accessing data submitted with a querystring <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); %>

  24. 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()"/>

  25. 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>

  26. Output

  27. <% 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; } %>

  28. Number to Currency Format • Import class: • %@page import="java.text.NumberFormat"% • Define a format: • NumberFormat nf = NumberFormat.getCurrencyInstance(); • Convert: • nf.format(value)

  29. 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);

  30. 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"); %>

  31. Read Cookies:Cookie is in array object, we need to get in request.getCookies() of array <% Cookie[] cookies = request.getCookies(); out.println(cookies[0].getName() + cookies[0].getValue() + "<br>"); out.println(cookies[1].getName() + cookies[1].getValue() + "<br>"); %>

  32. 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);

  33. 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

  34. Add an object to session objectAdd 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"); %>

  35. Retrieve an object from session <% Object custName; custName=session.getAttribute("Cname"); out.println("Welcome, " + custName.toString()); %>

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