Day 6

Quiz

A1:	The following custom tag types can be developed for a JSP: simple custom tag; simple custom tag with attributes, Simple Custom Tag with Attributes Defining Scripting Variables, Custom Tag with Body Noninteractive and Interactive tags, and Cooperating Custom Tags.
A2:	For a simple custom tag, the doStartTag(), doEndTag(), and the release() methods need to be overridden. Also, the doEndTag() method must return the constant EVAL_PAGE to continue processing of the JSP page.
A3:	For a simple custom tag with attributes, the doStartTag(), doEndTag(), setAttrib1...N(), getAttrib1...N(), and release() methods need to be overridden. Also, the doEndTag() method must return the constant EVAL_PAGE to continue processing of the JSP page. The same is the case for a Simple Custom Tag with Attributes Defining Scripting Variables.
A4:	To build a custom tag with the body-interactive tag, you need to override the doStartTag(), doInitBody(), doAfterBody(), doEndTag(), and release() methods. Also, the doStartTag() method must return the constant value EVAL_BODY_TAG.
A5:	For implementing a custom tag without a body, the tag handler class needs to either implement the methods of the Tag interface or override the methods of the TagSupport class. A tag handler for a custom tag with a body either implements the methods in the TagBody interface or overrides the methods of the BodyTagSupport class.

Exercises

A1:	Create a Java file called ValidateDateFormat.java which inherits the validation functionality of the CustomizableAdapter class supplied by WebLogic Server to build a custom validator library for JavaServer Pages: package weblogicx.jsp.tags.validators; import javax.servlet.ServletRequest; // Referenced classes of package weblogicx.jsp.tags.validators: // CustomizableAdapter public class ValidateDateFormat extends CustomizableAdapter { public ValidateDateFormat() { } public boolean equals(Object obj) { if(obj == null) return false; if(obj instanceof ValidateDateFormat) { ValidateDateFormat validateDateFormat = (ValidateDateFormat)obj; if(getFieldToValidate().equals(validateDateFormat. getFieldToValidate()) && getErrorMessage(). equals(validateDateFormat.getErrorMessage())) return true; } return false; } public boolean validatedate(ServletRequest servletrequest) throws Exception { String correctDateFormat = "MM/DD/YYYY"; String requestDateFormat = super.fieldToValidate; try { SimpleDateFormat simpleFormat = new SimpleDateFormat(correctDateFormat); simpleFormat.setLenient(false); Date simpleFormatDate = simpleFormat.parse(requestDateFormat); } catch (ParseException e) { return false; } catch (IllegalArgumentException e) { return false; } return true; } } Then, in the taglib.tld of the weblogic-vtags.jar, add the following tag: <tag> <name>validatedate</name> <tagclass>weblogicx.jsp.tags.validators.ValidateDateFormat </tagclass> <bodycontent>JSP</bodycontent> <info> A customized class developed as an extension to the weblogic tag lib </info> <attribute> <name>fieldToValidate</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>errorMessage</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>expression</name> <required>false</required> <rtexprvalue>false</rtexprvalue> </attribute> <attribute> <name>validatorClass</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> In the ShoppingCartJsp.jsp JSP file that you used in the sample program, include the following code snippet between the display table of the book shopping cart and the submit buttons table: <TD><FONT face="Helvetica" size=2> Date: Enter date in the MM/DD/YYYY format </FONT></td> <TD width=33% ><FONT face="Helvetica" size=2> <input type="text" name="dateValue">%> </FONT></TD> <TD> <wl:validatedate fieldToValidate="dateValue" validator errorMessage="Date is not in the proper format" > <font color="red"> Date is not in the proper format. Enter it in the MM/dd/yyyy format </font> </wl:validator></TD> Now, deploy the custom tag library by following the steps described today, and your custom validator is ready!
A2:	First create the tag support class called RoundPrice: package com.sams.learnweblogic7.tagLibClasses; import java.io.*; import java.util.*; import javax.servlet.*; import javax.servlet.jsp.*; import javax.servlet.jsp.tagext.*; import com.sams.learnweblogic7.utils.*; /** * This class displays the amount in the rounded format. */ public class RoundPrice extends TagSupport{ private double bookPrice; public int doStartTag() { System.out.println("Inside the tag in dostart"); try{ JspWriter out = pageContext.getOut(); bookPrice = getBookPrice(); out.println(Utility.getRoundedAmount(bookPrice)); } catch(Exception e){ System.out.println("Please check your code"); e.printStackTrace(); } finally{ return(SKIP_BODY); } } public void setBookPrice(double moneyVal){ this.bookPrice = bookPrice; } public double getBookPrice(){ return bookPrice; } } Now create the entry in customTagTLD.tld: <tag> <name>RoundPrice</name> <tagclass>com.sams.learnweblogic7.tagLibClasses.RoundPrice</tagclass> <bodycontent>empty</bodycontent> </tag> Add the following attribute tag in the web.xml file, inside the existing tagLib attribute: <attribute> <name>RoundPrice</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> Next you need to alter the JSP. The book price will be calculated via the following: double totBook1Price = book1Qty * book1.getBookPrice(); double totBook2Price = book2Qty * book2.getBookPrice(); double totBook3Price = book3Qty * book3.getBookPrice(); double grandTotal = totBook1Price + totBook2Price + totBook3Price; Now the code to display the table in the ViewCartJsp.jsp will look as follows: <wl:cache name="commonHeader" scope="session"> </wl:cache> <CENTER><B>Your Shopping Cart Contains:</B></CENTER><BR> <TABLE width = 100%> <TR> <TH>&nbsp;</TH> <TH>Book Name and description</TH> <TH>Book Price</TH> <TH>Qty</TH> <TH>Total for each book</TH> </TR> <wl:cache name="book1Vars" scope="session"></wl:cache> <TD align='center'><%=book1Qty%></TD> <TD align='center'> $<ctt:RoundPrice BookPrice="<%=totBook1Price%>"/> </TD> </TR> <wl:cache name="book2Vars" scope="session"></wl:cache> <TD align='center'><%=book2Qty%></TD> <TD align='center'> $<ctt:RoundPrice BookPrice="<%=totBook2Price%>"/> </TD> </TR> <wl:cache name="book3Vars" scope="session"></wl:cache> <TD align='center'><%=book3Qty%></TD> <TD align='center'> $<ctt:RoundPrice BookPrice= "<%=totBook3Price%>"/></FONT> </TD> </TR> <TR bgcolor='#eeeeee'> <TD>&nbsp;</TD> <TD>&nbsp;</TD> <TD>&nbsp;</TD> <TD>&nbsp;</TD> <TD align='left'> <B>Total=$<ctt:RoundPriceBookPrice="<%=grandTotal%>"/></B> </TD> </TR> </TABLE> <p align ="left"> <INPUT type="submit" name="buttonName" value="Empty Shopping Cart"> </p>