Member variable for jsp tag

Hi,
is it safe to have member variables in jsp tag? every time service method will create new instance of tag?Thanks

is it safe to have member variables in jsp tag? The answer is yes, but.
every time service method will create new instance of tag?no, it will not necessarily create a new instance every time.
For most tags I believe the spec allows for a 'pool' of tag handlers to be retained.
Certainly I have seen this happen in tomcat.
An exception is the JSP2.0 SimpleTagHandler which guaruntees that it will be used once and then thrown away.
With other tags, you have ownership of the tag and its member variables, between doStartTag and doEndTag. Nothing else can interfere with the member variables.
However if you include the tag twice in your page, one after another, it is quite possible, that you will be given the same tag object, and thus the member variables might have variables set from the previous use of the tag.
It is fairly easy to work around though
in the doStart: init any member variables that are not defined by attributes to be their default values
in the doEnd method, clean up your member variables. Clear any attribute values that might be optional. Set things to null. That way you are guarunteed that if the tag is reused, it won't pick up any data from your run through here.
But don't take my word for it :-) Try it out.
Hope this helps,
evnafets

Similar Messages

Search strategy for JSP tag files

Hello everyone,
I've been trying to find a solution to this for some time, but couldn't find a clean one. Maybe somewhere here has any ideas for a solution...
Consider a JSP taglib which is composed of hundreds of .tag files. The library is referenced in JSP using the "*tagdir*" option of the taglib directive, which simply points to /WEB-INF/tags/ (where the .tag files are located).
Our standard server software distribution includes that tag library, as well as JSP pages that make up the server's web user interface. Those JSP pages use the taglib extensively.
Now, we want to be able to distribute upgrades to the JSP pages and the tablib, but allow customers to easily customize some tag files without worring about loosing their changes if they apply a future upgrade.
If it were possible for JSP pages to declare two overlapping taglib directives (same prefix) pointing to two different tagdirs, it would allow us to place our hundreds of .tag files in one "standard" directory, and allow customers to place customized .tag files in another "customized" directory. That way JSP files would always use the same prefix for our tags, but the actual .tag file inserted would be coming either from the customers's "customized" tagdir or from our "standard" tagdir (depending if they chose to override a tag with a customized version or not).
Is this possible? How do people deal with taglib customization and maintenance issues?
Thank you!

Thanks for the reply!
We use the ClickOnce smart client deployment to the user's machine and we would not want to touch/change anything on the user's machine. So, we can't rely on an environment variable being set.
It almost seems that the DB Support Team has to not only talk to the Tech Support team and arrange for deploying the right version of the tnsnames.ora file on their users machines, but also talk to the App Deployment Team and provide the most recent version of this file to be used for deployment. So I guess if this file is checked in a code repository, the DB Support team can notify the Tech Support Team and the App Deployment Team to refresh respectively all user machines and application deployment configuration files.
Alternatively, as one of the app deployment instructions of App Deployment team can be: "check out the most recent version of tnsnames.ora from the repository before deploying the application".
Any thoughts?
Thanks.
Regards,
gkk1969

Using jsp variables within JSP tag

I have a variable defined within a JSP:
<%
String cust_id = request.getParameter("cust_id");
%>
I want to use this variable as a parameter to a custom tag:
<%@ taglib uri="/tlds/DBTags.tld" prefix="db" %>
<db:MultiColumnSelect columns="c.id, c.po" name="ccar_id" table_name="ccar_headers c, ccar_rmas r" selectString="r.ccar_id = c.id AND c.cust_id = <%= cust_id %>"/>
The selectString value that is passed to my tag is:
r.ccar_id = c.id AND c.cust_id = <%= cust_id %>
The <%= cust_id %> is not replaced by the actual variable value.
How would I accomplish using this variable within my JSP tag?

Your definition of the selectString attribute must indicate that it can accept runtime expressions.
<%
String cust_id = request.getParameter("cust_id");
String selectString = new String("r.ccar_id = c.id AND c.cust_id = " + cust_id);
%>
<%@ taglib uri="/tlds/DBTags.tld" prefix="db" %>
<db:MultiColumnSelect columns="c.id, c.po" name="ccar_id" table_name="ccar_headers c, ccar_rmas r"
selectString="<%= selectString %>"/>

Session-scope variable for JSP page used in a frame

Hi,
I don't know if there's a way to do this at the same time:
(1)- assign session scope to a variable (in order to be able to retrieve recurrently the previous value each time the JSP is called);
(2)- set its visibility in a way that it could be accessed only by the page that defines it. The JSP is used in a frameset along with an other JSP that can potentially define identical session-scoped variable (You understand why I want to keep them separate)
session.setAttribute():
seems not to be the thing I need
pageContext.setAttribute():
with SESSION_SCOPE, it behaves the same way as session.setAttribute(). with PAGE_SCOPE, condition (1) can't be satisfied.
Does anybody have an idea ?
Thanx in advance.

I can see that you will not want to maintain two different files for every possible page on the site!
It may be possible to do something like <frameset rows="*" cols="50%,*">
<frame name="content1" src="file.jsp?frame=one" >
<frame name="content2" src="file.jsp?frame=two" >
</frameset>and then in the jsp<%
String frame=request.getParameter("frame");
session.setAttribute(frame+"AttributeName",attributeValue);
%>This will set up two session attributes - "oneAttributeName" and "twoAttributeName". Depending on how many variables you have, this may prove just as difficult to maintain.
You may end up having to simply pass url parameters between pages to maintain state within the individual frames, which is far from elegant also.
I am interested in how you end up solving this one.

Problem with jsp tag in jsf file c:import


<jsp:include page="#{backing_Home.whichMenu}"/>
I am trying to use a JSF variable in jsp tag
I am getting error like this
javax.servlet.jsp.JspTagException: /#{backing_Home.whichMenu}     at org.apache.taglibs.standard.tag.common.core.ImportSupport.acquireString(ImportSupport.java:318)     at org.apache.taglibs.standard.tag.common.core.ImportSupport.doEndTag(ImportSupport.java:186)     at _Home_2e_jsp._jspService(Home.jsp:24) I want to add a page dynamically using that variable
Is there any other method

This code works fine for me:
<%@ taglib uri="/jstl-c" prefix="c" %>
<html>
     <body>
     <%
          int array[] = new int[] {1,2};
          session.setAttribute("array", array);
          String arrayNames[] = new String[]{"One", "Two"};
          session.setAttribute("arrayNames", arrayNames);
     %>
          <form action="?">
          <select name="select">
               <c:forEach items='${ sessionScope.array}' var="row">
                    <c:choose>
                         <c:when test="${param.select== row}"> >
                              <option value="<c:out value='${row}'/>" selected><c:out value="${sessionScope.arrayNames[row-1]}"/></option>
                         </c:when>
                         <c:otherwise>
                              <option value="<c:out value='${row}'/>"><c:out value="${sessionScope.arrayNames[row-1]}"/></option>
                         </c:otherwise>
                    </c:choose>
               </c:forEach>
          </select>
          <input type="submit" name="submit" value="submit"></input>
          </form>
     </body>
</html>
good luck.
MatrixPooh
www.bizdisplay.com

Deployment for JSP Application on OAS 4.0.8.2

Hi,
I would appreciate, if someone could share its experience of deploying the JSP application which utilizes certain JavaClasses for database access and businesslogic.
My question is that do we need to add JSP files or .java files created under the myprojects directory. Also where do we place the java classes.
Also, do I need to get my classpath settings in the environment variables for JSP's to run. Because my WinNT crashed twice on changing the env settings.
Any help shall be appreciated
Thanks

Hi ,
As u had said in the previous mail... I also have lot of basic doubts. Let us share them..
What do u mean by a JSP cartridge... Should i download it or something...
Regards,
Ganesh R

Passing struts-tag value to java / javascript variable in JSP

Hello all,
Im trying to pass the value got from the struts-tag to the java variable in the Jsp. However Im not able to get the o/p. Can u guys help me on this pls...
<logic:notEmpty name="TreeBean" property="list">
    <logic:iterate id="Type" name="TreeBean" property="list" indexId="i">
     <br/><bean:write name="Type" />
    </logic:iterate>
</logic:notEmpty>Here the list can be populated in the jsp page. However i want the values into jsp list. Im not able to populate the same..
<% List jspList = null;
%> I want the values into the jspList variable for further processing. Can u guz pls help me on this....

Which do you want it in?
A java variable for use in <% scriptlet code %> or a javascript variable for use on the client end?
scriptlet:
<jsp:useBean id="TreeBean" type="java.util.List" class="java.util.ArrayList" scope="?????" />
Having scriptlet code on the page is considered bad coding style.
What is it you are trying to accomplish by making the value accessible?
What are you trying to do in java / javascript that can't be done with JSP tags?

Justifications needed for using tags in JSP, Please reply

Hi forum
My question is to those java people who have also done JSP. I m sound in java server side (servlet programming), now I have asked by my project manager to do server side programming in JSP using tagLibraries (as these are used by those ppl who didnt have much java knowledge). I have worked inserver side java, then my question is y should I start working on tags,
On the other hand I can do all the work in java embedding in JSP (on some extent, seperated by diffrent helper/util classes to reduce the thickness of JSP page).
so I want to ask u ppl that should a java programmer needs to use tag libraries to code a JSP page, however he can code it in java directly.
I will feal great pleasure if u will write ur opinions and help me to ease my life.
thanx in advance
Best Regards
Tahir

You should use tag libraries whenever you can because:
1) They increase code re-useability. You can insert the same tag in many pages using just a few lines to do complex tasks, as opposed to writing a lot of scriptlet code in each JSP.
2) Enhance your ability to seperate logic from display. Everything in your tags is logic. Everything in your JSP is display - with the tags bridging the logic to the display.
3) Make the JSPs cleaner and easier to maintain. They read easier with tags than with a lot of scriptlets. Non-java people can be used to update the look and feel of the web page, or to debug the HTML later on, relieving the Java programmers for the tag work, or other jobs more suited to them.
4) Your boss said to do tags, so do tags.

GetVariable() doesn't work in FireFox for object member variables

I'm trying to access Flash member variables from Javascript
using GetVariable. The following line of code works for IE but not
for Firefox:
var variable = swf.GetVariable("someObject.someProperty");
In IE, the GetVariable() function returns the correct value
for the property. However in Firefox, the GetVariable() function
returns "null" when trying to access the property. If I just try to
access the object in Firefox (i.e. swf.GetVariable("someObject"), I
get a string back (instead of the object that I am expecting). If I
try to access a variable (such as a string) and not an object using
GetVariable(), this works in both Firefox and IE.
Any ideas what I am doing wrong? I suspect that my syntax for
accessing object member variables in Firefox is incorrect but I
have not been able to find any documentation on the correct syntax.
Any assistance would be greatly appreciated.
Thanks.

Thanks, but this isn't an issue.
The window.document.flashMovie will return the correct flash
object/embed flash movie.
The issue is that the GetVariable method wont return the
object variable. When you try to get an simple variable that is in
the _root timeline, it will return the value. Example:
movie.GetVariable(_url) will return the url of the flash
movie without any problem.
But when you create an ActionScript class with
userName property and then you will create the instance of
it in the _root, you should be able to get it's value. Example:
Flash:
var obj = new SomeClass();
obj.userName = "peter";
JavaScript:
movie.GetVariable("/obj:userName");
or
movie.GetVariable("obj.userName");
This will return
Peter for IE and null for Forefox/Opera.
The same when you use the document.embeds[..].

Design view for jsp custom tags.

when we drag-and-drop custom tag control in the source of jsp page, when we switch to the design view of jsp we should be able to view controls as desired.
Observation: 1) Eclipse 3.2 doesn't have design view for jsp pages.
2) which software uses the design view. we need to extend eclipse core framework and we do not find any technical approach document to proceed further on this.
3) RAD 6.0 we can see a JSP in design view.
I'm searching for any technical approach document to create plugin that can intercept the custom tags and provide a design view.
Will any one suggest the plugin for that.

Jeff,
I have checked with engineering and found that JSP Design View support on
Linux is a planned feature for the next release. I don't think we will have
this feature as part of a Service Pack for 8.1
Regards,
Raj Alagumalai
WebLogic Workshop Support
"Jeff Cassanvoa" <[email protected]> wrote in message
news:3f4df04e$[email protected]..
>
Raj,
Thanks for the information!! Any timeframe when it might be supportedon Linux
Thanks,
Jeff
"Raj Alagumalai" <[email protected]> wrote:
Jess,
Unfortunately, the JSP design view is currently not supported on Linux.
Workshop does allow to do remote development where the IDE is running
on a
Windows machine and connects to a server running on Linux/Solaris.
Regards,
Raj Alagumalai
WebLogic Workshop Support
"Jeff Cassanova" <[email protected]> wrote in message
news:[email protected]..
Does anybody else who is running the Linux version of Workshop 8.1have
troubling
getting the Design View of JSP files to come up. All I see is thesource,
with
no tabs at the bottom to switch to/from the Design View. When I bootover
to
Windows and run 8.1 Workshop, I see both tabs and I am able to useboth
views.
Is it something I have set in Preferences somewhere that disablesthe
Design
View ???
Thanks,
Jeff

Can I write Design-time for JSP custom tag(not JSF components)

I have some old JSP custom tags(not JSF components), and I want to use them in the IDE through the toolbox.
Now I have already written the BeanInfos for these tags, and they can be drag from the toolbox; but it will throw a Exception when render the tags, and the properties in the Property Editor are not which I describe in the BeanInfos.
How can I write Design-time for these tags? or whether it is possible to write the Design-time for these tags?
the Exception is shown as follow:
java.lang.ClassCastException
     at com.sun.rave.insync.faces.FacesPageUnit.renderNode(FacesPageUnit.java:1347)
[catch] at com.sun.rave.insync.faces.FacesPageUnit.renderBean(FacesPageUnit.java:1086)
     at com.sun.rave.insync.faces.FacesPageUnit.getFacesRenderTree(FacesPageUnit.java:993)
     at com.sun.rave.css2.FacesSupport.getFacesHtml(FacesSupport.java:152)
     at com.sun.rave.css2.CssContainerBox.addNode(CssContainerBox.java:373)
     at com.sun.rave.css2.CssContainerBox.createChildren(CssContainerBox.java:354)
     at com.sun.rave.css2.DocumentBox.createChildren(DocumentBox.java:90)
     at com.sun.rave.css2.DocumentBox.relayout(DocumentBox.java:160)
     at com.sun.rave.css2.PageBox.layout(PageBox.java:392)
     at com.sun.rave.css2.PageBox.relayout(PageBox.java:454)
     at com.sun.rave.css2.DocumentBox.redoLayout(DocumentBox.java:313)
     at com.sun.rave.css2.PageBox.redoLayout(PageBox.java:460)
     at com.sun.rave.css2.DocumentBox.changed(DocumentBox.java:634)
     at com.sun.rave.designer.DesignerPaneUI$UpdateHandler.changedUpdate(DesignerPaneUI.java:1012)
     at com.sun.rave.text.Document.fireChangedUpdate(Document.java:851)
     at com.sun.rave.text.Document$5.run(Document.java:631)
     at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:178)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:454)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)

I have some old JSP custom tags(not JSF components), and I want to use them in the IDE through the toolbox.
Now I have already written the BeanInfos for these tags, and they can be drag from the toolbox; but it will throw a Exception when render the tags, and the properties in the Property Editor are not which I describe in the BeanInfos.
How can I write Design-time for these tags? or whether it is possible to write the Design-time for these tags?
the Exception is shown as follow:
java.lang.ClassCastException
     at com.sun.rave.insync.faces.FacesPageUnit.renderNode(FacesPageUnit.java:1347)
[catch] at com.sun.rave.insync.faces.FacesPageUnit.renderBean(FacesPageUnit.java:1086)
     at com.sun.rave.insync.faces.FacesPageUnit.getFacesRenderTree(FacesPageUnit.java:993)
     at com.sun.rave.css2.FacesSupport.getFacesHtml(FacesSupport.java:152)
     at com.sun.rave.css2.CssContainerBox.addNode(CssContainerBox.java:373)
     at com.sun.rave.css2.CssContainerBox.createChildren(CssContainerBox.java:354)
     at com.sun.rave.css2.DocumentBox.createChildren(DocumentBox.java:90)
     at com.sun.rave.css2.DocumentBox.relayout(DocumentBox.java:160)
     at com.sun.rave.css2.PageBox.layout(PageBox.java:392)
     at com.sun.rave.css2.PageBox.relayout(PageBox.java:454)
     at com.sun.rave.css2.DocumentBox.redoLayout(DocumentBox.java:313)
     at com.sun.rave.css2.PageBox.redoLayout(PageBox.java:460)
     at com.sun.rave.css2.DocumentBox.changed(DocumentBox.java:634)
     at com.sun.rave.designer.DesignerPaneUI$UpdateHandler.changedUpdate(DesignerPaneUI.java:1012)
     at com.sun.rave.text.Document.fireChangedUpdate(Document.java:851)
     at com.sun.rave.text.Document$5.run(Document.java:631)
     at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:178)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:454)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)

JSP tags for managing MBeans??

Hi,
I'm trying to build a GUI for managing a custom MBean. The MBean implementation is a wrapper for a singleton class (specifically, a Configuration class for a web app). I've tried using WebJMX, but the problem there is that it relies heavily on MX4J, and has not kept up with JMX advances in the last two years (MX4J is a bit ahead of weblogic 8.1).
Just as there is a set of console extension jsp tags, I suspect that a set of JSP tags exists for the developers of the Weblogic console to write their JSP pages to manage the weblogic MBeans. I coud just try to figure out the pattern of the INPUT and FORM tags in the html, but that leaves me with a possibly-inaccurate, version-dependent, non-dynamically-generated page to manage one MBean.
Does such a set exist? Could someone point me to any information about how to use such a set of tags?
I would like to be able to have the JSP I use for my console extension display an interface for modifying MBean configurable fields and executing MBean operations. What would the best way be to do this? I do not want to embed the Sun JMX RI in my web-app and launch a separate HtmlAdaptor listening on a different port. I would like the admin to the MBean be accessible through (and only through) the weblogic console.
Thanks in advance for the help,
Matt Geis

Hi,
I'm trying to build a GUI for managing a custom MBean. The MBean implementation is a wrapper for a singleton class (specifically, a Configuration class for a web app). I've tried using WebJMX, but the problem there is that it relies heavily on MX4J, and has not kept up with JMX advances in the last two years (MX4J is a bit ahead of weblogic 8.1).
Just as there is a set of console extension jsp tags, I suspect that a set of JSP tags exists for the developers of the Weblogic console to write their JSP pages to manage the weblogic MBeans. I coud just try to figure out the pattern of the INPUT and FORM tags in the html, but that leaves me with a possibly-inaccurate, version-dependent, non-dynamically-generated page to manage one MBean.
Does such a set exist? Could someone point me to any information about how to use such a set of tags?
I would like to be able to have the JSP I use for my console extension display an interface for modifying MBean configurable fields and executing MBean operations. What would the best way be to do this? I do not want to embed the Sun JMX RI in my web-app and launch a separate HtmlAdaptor listening on a different port. I would like the admin to the MBean be accessible through (and only through) the weblogic console.
Thanks in advance for the help,
Matt Geis

Jsp tag for blog attribute in a flex asset

hi Experts,
I am using FW7.6.1, I have a flex asset with a blob attribute, when I create that flex asset, I can upload an image in that attribute, but I did not find a jsp tag for rendering that attribute which has a image saved, another question is what jsp tag should be used in case of a word file is uploaded in that attribute, that's to say:
1. for a image, I want to display it in browser.
2. for a word file, I want to show popup window to ask user if he wants to download or open.
By using assetset:getattributevalues and render:stream, it's just for string type of attribute, not for blog.
Thanks in advance.
Best regards

hi all,
I got the answer from dev guide, seems should use:
<blobservice:gettablename varname="uTabname"/>
<blobservice:getidcolumn varname="idColumn"/>
<blobservice:geturlcolumn varname="uColumn"/>
and render:satelliteblob
some complicated then I expected.
Best regards

Custom JSP Tags for Weblogic

Hi,
          I have several questions regarding this topic:
          1) Does Weblogic 5.1 supports Custom Tags ? If so, are there any known
          problems ?
          2) Does Weblogic come with any tag libraries (for loops, if, etc) and where
          can I get them ?
          3) Are there any tag libraries out there (JRun, for example) that have been
          successfully run on Weblogic ?
          Any help would be much appreciated.
          Thanks,
          Jamie


As there seems to be general interest, a link would probably be a great
          help.
          Regards
          Daniel Hoppe
          -----Original Message-----
          From: Michael Girdley [mailto:[email protected]]
          Posted At: Friday, August 25, 2000 8:03 AM
          Posted To: jsp
          Conversation: Custom JSP Tags for Weblogic
          Subject: Re: Custom JSP Tags for Weblogic
          Please see the documentation:
          http://www.weblogic.com/docs51/resources.html
          Michael Girdley
          BEA Systems Inc
          "Jamie" <[email protected]> wrote in message
          news:[email protected]...
          > Update
          > =======
          >
          > Weblogic Portal has some Tag libraries. I've downloaded the trial
          version
          > of
          > the Weblogic Commerce Server. How do I get the tag libraries and use
          them
          > on WL 5.1 ?
          >
          > Answers to original post still wanted
          >
          > Thanks,
          >
          > Jamie
          >
          > Jamie <[email protected]> wrote in message
          > news:[email protected]...
          > > Hi,
          > >
          > > I have several questions regarding this topic:
          > >
          > > 1) Does Weblogic 5.1 supports Custom Tags ? If so, are there any
          known
          > > problems ?
          > >
          > > 2) Does Weblogic come with any tag libraries (for loops, if, etc)
          and
          > where
          > > can I get them ?
          > >
          > > 3) Are there any tag libraries out there (JRun, for example) that
          have
          > been
          > > successfully run on Weblogic ?
          > >
          > >
          > > Any help would be much appreciated.
          > >
          > > Thanks,
          > >
          > > Jamie
          > >
          > >
          >
          >

Why does people use JSP Tag for their JSP page? (Urgent)

I don't know what benifit if I am using JSP Tag.
If anyone knows, pls give me an idea and the advantage of using JSP Tag in JSP Page!
Thanks in advance!

You have to read a little about JSP, JSP stands for JavaServer Pages, you can use jsp tags and you can use java code. If you dont want to use jsp tags then you should just write html file, if you just want to use java, then write java class or a servlet.
The need for jsp arised because people were inserting html code inside a servlet class..a big no no..and a headache. JSP separate model from the view...read a little about MVC-2 model view controller pattern.
Also read some tutorial on this website...good luck
K

Member variable for jsp tag

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