Techie Notes: JSP

Showing posts with label JSP. Show all posts

Tuesday, April 23, 2013

Custom JSP tags

1) Make sure that the library for tags is in your classpath. servlet-api-2.3.jar supports it.
2) Create the tag class
Ex.
public class MyTag extends TagSupport
public class HelloTag extends SimpleTagSupport
3) Create the tag libray descripto file and put anywhere inside WEB-INF directory
Ex. WEB-INF/tld/myApp.tld

<taglib>
  <tlib-version>1.0</tlib-version>
  <jsp-version>2.0</jsp-version>
  <short-name>Example TLD</short-name>
  <tag>
    <name>Hello</name>
    <tag-class>com.tutorialspoint.HelloTag</tag-class>
    <body-content>empty</body-content>
  </tag>
</taglib>

4) Use the tag. You can also set uri in tld and use it as your uri in JSP page.

<%@ taglib prefix="ex" uri="WEB-INF/tld/myApp.tld"%>
<html>
  <head>
    <title>A sample custom tag</title>
  </head>
  <body>
    <ex:Hello message="This is custom tag" />
  </body>
</html>

Sunday, September 12, 2010

JSP / JSTL / EL

JSP
JavaServer Pages (JSP) - is the standard presentation-layer technology for the J2EE platform.

JSP scripting elements:

expressions
- form: <%= javaExpression %>
- ex: date = <%= new java.util.Date() %>
- xml syntax: <jsp:expression>javaExpression</jsp:expression>
scriptlets
- form: <% code %>
- xml syntax: <jsp:scriplet>code</jsp:scriplet>
declarations
- form: <!% code %>
- xml syntax: <jsp:declaration>code</jsp:declaration>

Comments

JSP Comment - <%-- JSP Comment --%>
HTML Comment -

Predefined vars: request, response, session, out, application, config, pageContext and page

JSTL
JSP Standard Tag Library (JSTL) - is a collection of standard custom tag libraries that implement basic functionality common to a wide range of server-side Java applications.

EL
Expression Language (EL) - is a simplified form for JSP expression
- syntax: ${elExpression}

Source:
http://www.ibm.com/developerworks/java/library/j-jstl0211.html
http://download.oracle.com/docs/cd/E17802_01/j2ee/j2ee/1.4/docs/tutorial-update2/doc/index.html

Monday, February 16, 2009

JSP Pointers

secure/nonsecure alerts on IE6 & 7

http://www.zorked.com/security/ie-mixed-content-secure-nonsecure-items/

no caching on browsers

  
< META HTTP-EQUIV="Expires" CONTENT="0"> - any # less than 1 means no cache
< META HTTP-EQUIV="Pragma" CONTENT="no-cache"> - for backward compatability
< META HTTP-EQUIV="Cache-Control" CONTENT="no-cache"> - for HTTP 1.1 spec

day in Date

function fnGetPrevDayDate(objDate){
 // 1 day = 86400000 ms 
 // var datPrevDate = new Date(objDate.getTime() - 86400000);
 // code above returns incorrect result when time changes from DST to standard time
 
 var datPrevDate = new Date(objDate);
 datPrevDate.setDate(datPrevDate.getDate() - 1);
 return datPrevDate;
}

html:checkbox

how to use indexId on logic:iterate

< logic:iterate id="entityRow" name="<%= DerivativeEntityConstantsIF.SEARCH_RESULT %>" scope="session" offset="<%= String.valueOf(offset)%>" length="<%= String.valueOf(maxLength)%>" indexId="indexNum">
  < html:select name="entityRow" property="linkageClassCode"
onchange='<%= "fnEditValue(this, " + indexNum + ")" %>' >...

html element default values - defaultValue/defaultSelectedd

if (frm["termDeal.accountNo"].value != frm["termDeal.accountNo"].defaultValue) return true;
if (fnIsSelectChanged(frm["termDeal.currency"])) return true;

function fnIsSelectChanged(selectObj) {
  var index = selectObj.selectedIndex;
  var selectedOption = selectObj.options[index];
  if (selectedOption.defaultSelected) return false; 
  return true;
}

use popUpCalendar.js

if (!document.layers){
var startDate = document.getElementById("personalInfoForm.dateOfBirth");
// use showCalendarWithHolidays if you want to show holidays
document.write("<[toRemove]a href='javascript:void(0)' onclick='showCalendarWithHolidays(this, startDate, \"mm-dd-yyyy\",null,1,-1,-1, true)'><[toRemove]img src='' border='0'/>");
}

regex of replace

.value.replace(/_|-/g, '')  --> replace _ and - with empty str

use of sessionScope

CL.isNewClient = ${sessionScope[ClientConstants.IS_NEW_CLIENT]} --> do not put semi colon at end (not sure if for AMS only)

Techie Notes