ConnCacheBean sample and useBean tag?

Hi,
In the ConnCacheBean sample code (JDBC 9i Sample Code), the Bean is instantiated in a scriptlet in each of the JSPs in the example:
// Instantiate and get instance of the Bean
ConnCacheBean myBean = ConnCacheBean.getInstance();
If you are using ConnCacheBean from more than one JSP, would it make more sense to have a useBean tag with application scope in each JSP:
<jsp:useBean id="ccb" class="packagename.ConnCacheBean" scope="application">
Just wondering if there is any particular reason that I am missing, that the code was written in the way it was?
thanks
Rob

Robert,
I would suggest you to keep this class as a singleton class. This is because, at any time, there should be only one copy of this class on the server or the JVM. Multiple copies of this class means that there is more than one place from where a class/JSP can get a connection. This means that the connection is instantiated more than once which defeats the whole purpose of Caching connections. You should avoid this.
What you are suggesting is fine if you are writing a small application, but you dont want multiple copies of this class even by mistake in a big application.
Thanks.

Similar Messages

Constructor parameter and useBean -tag

Greetings,
Is there a way to pass a contructor parameter when using the JSP tags:
<%@ page import="DBTool" %>
<jsp:useBean id='manager' scope="application" class=DBTool/>
The DBTool class needs init parameters in the contructor, but I don`t know any way how to do it when using the useBean tag?
Regards,
Eki

This is as close as you are going to get. The code within the jsp:useBean tag will only get executed when the object needs to be created. With a scope of application, it will only get run once unless you call application.removeAttribute("manager") OR getServletContext().removeAttribute("manager").
Hope this helps
<%@ page import="DBTool" %>
<jsp:useBean id="manager" scope="application" class="DBTool">
       <%
           manager.setProperty1(13);
           manager.setMyProperty2("MyProperty");
       %>
</jsp:useBean>OR if you want it to be cleaner
<%@ page import="DBTool" %>
<jsp:useBean id="manager" scope="application" class="DBTool">
       <% manager.init(parms); %>
</jsp:useBean>

How to use "scope " attrubute in useBean tag

Can anyone please tell me if I can use the same JavaBean Class to hold information form different pages? well, let me explain exactely what I want to do:
I have a Java bean Class that holds a property 'Name':
package ContactManager;
public class Person {
private String name="%";
public String getName () {
return this.name;
public void setName (String my_name) {
name = my_name + "%" ;
I'm using this class to store temporarly the Criteria of search from a JSP/HTML page to send to a database for search and for UPDATE -> this of course is done in different HTML/JSP pages. The problem I have is that the first time I set the properties (when the user make a search) this value remains unchanged [-> the second time when the user asks for update, I try to use the same bean to keep the value => unfortuntly it returns me the old value]
My question is: is the use of 'scope' attribute of the "jsp:useBean" tag can solve this problem? if yes how to use it? I've tryed to set the scope of the bean to page but that does not help :-(
Pleaze help, I'm stuck.... Bellow is the 4 JSP pages for:
- person_search.jsp / person_result.jsp
- request_modify.jsp/ DoModify.jsp
1 -person_search.jsp
<%@ page import="java.sql.*" %>
<HTML>
<HEAD><TITLE>Person Search</TITLE></HEAD>
<BODY><CENTER>
<form method="POST" action="person_result.jsp">
Name <input type="text" name="name" size="47"></p>
<input type="submit" value="Submit" name="B1">
<input type="reset" value="Reset" name="B2"></p>
</form></body>
</html>
2- person_result.jsp
<%@ page import="java.sql.*" %>
<HTML><BODY>
<jsp:useBean id="theBean" class="ContactManager.Person"/>
<jsp:setProperty name="theBean" property="*" />
Name<BR>
<%
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
System.out.println("JDBC driver loaded");
catch (ClassNotFoundException e) {
System.out.println(e.toString());
%>
<%
try {
Connection con = DriverManager.getConnection("jdbc:odbc:ContactManager");
Statement s = con.createStatement();
String sql = "SELECT Client.ClientID, Client.Name FROM Client where Client.Name like " + "'" + theBean.getName() + "'";
ResultSet rs = s.executeQuery(sql);
while (rs.next()) {
String myId = rs.getString(1);
%>
<TR>
<TD><%= myId %></TD>
<TD><a href="person_detail.jsp?id=<%= myId %>"><%=rs.getString(2)%></a></TD>
<TD><a href="delete_person.jsp?id=<%= myId %>">Delete</a></TD><BR>
</TR>
<%
rs.close();
s.close();
con.close();
catch (SQLException e) {
System.out.println(e.toString());
catch (Exception e) {
System.out.println(e.toString());
%>
</BODY>
</HTML>
3- request_modify.jsp
<%@ page import="java.sql.*" %>
<html>
<head><title>AddressBook: Modifying Person <%= request.getParameter ("id") %></title> </head>
<body bgcolor="#ffffee">
<%
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
System.out.println("JDBC driver loaded");
catch (ClassNotFoundException e) {
System.out.println(e.toString());
%>
<%
int rowsAffected = 0;
try {
Connection con = DriverManager.getConnection("jdbc:odbc:ContactManager");
Statement s = con.createStatement();
String sql = "SELECT Client.ClientID, Client.Name FROM Client where ClientID ="+ request.getParameter("id");
ResultSet rs = s.executeQuery(sql);
if (rs.next()) {
%>
Client Name is <input type=text name=name value=<%= rs.getString(2) %>> <br>
<TD><a href="person_do_modify.jsp?id=<%= rs.getString(1)%>">Confirm Modify</a></TD>
<%
rs.close();
s.close();
con.close();
catch (SQLException e) {
System.out.println(e.toString());
catch (Exception e) {
System.out.println(e.toString());
%>
</BODY> </HTML>
4- do_modify.jsp
<%@ page import="java.sql.*" %>
<html>
<head><title>AddressBook: Modifying Address <%= request.getParameter ("id") %></title></head>
<body bgcolor="#ffffee">
<jsp:useBean id="theBean" class="ContactManager.Person" scope="page"/>
<jsp:setProperty name="theBean" property="name"/>
<%
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
System.out.println("JDBC driver loaded");
catch (ClassNotFoundException e) {
System.out.println(e.toString());
%>
<%
int rowsAffected = 0;
try {
Connection con = DriverManager.getConnection("jdbc:odbc:ContactManager");
PreparedStatement preparedStatement = con.prepareStatement ("UPDATE Client SET Name=? WHERE ClientID =?");
preparedStatement.setString (1, theBean.getName());
preparedStatement.setString (2, request.getParameter("id"));
rowsAffected = preparedStatement.executeUpdate ();
preparedStatement.close ();
if (rowsAffected == 1) {
%>
done
<%
else{
%>
Not Modified
<%
con.close();
catch (SQLException e) {
System.out.println(e.toString());
catch (Exception e) {
%>
</BODY></HTML>
Thank you for the help.
Sammy

While a quick search on the <jsp:useBean> tag and the scope attribute will probably yield more information than I can summarize in a few sentences, I'm pretty sure that using the scope="page" attribute on a bean will cause that bean to be instantiated every time the page is loaded. In order for a bean to persist longer than the existance of that page (whether you're loading a new page, or reloading the same one), you'd need to set the scope to session or application (you'd probably want session).

How can i load A gui JTable bean through jsp:useBean tag in a jsp page

Hi,
i am chiranjit , i am in a jsp project . i am desparately looking a solution for below stated problem:
i want to make a jsp page for master entry , that why i want to load a GUI Java bean in my jsp page.This GUI Bean contaning a JTable in which allow grid type data entry in the jsp page. But i am unable load that bean in the jsp page through jsp:useBean tag in my page.So if you have any solution then send in the forum as early as possible.
Thank you
chiranjit

No can do. JSPs can only output plain HTML (and javascript...) They are not used like normal Java classes.
If you need a complex GUI then you might use an Applet instead. If you want to use a JSP then you are stuck using normal HTML components, like <table> <form...> <input type="text"> etc...

Calling an inner class in a jsp:usebean tag

Hi everybody !
Here's my problem : working in my project on multiple pages, I'm using inner classes/beans to limitate my '.java' files but I'm stuck when calling that 'inner-bean' in my jsp:usebean tag.
First, I tried to declare in the class parameter : 'class="MyPrincipalBean.theInnerBean" but jsp returns me a 'not found' message.
I tried an other issue with this :
'class="MyPrincipalBean$theInnerBean" but I encountered a 'Attempt to use a bean type without a void constructor in jsp:useBean tag (JSP 1.1 specification, 2.13.1)'. Since I can't find that specification, I'm sending an SOS.
Am I on the good way ? If somebody as encoutered that sort of problem, it would be very kind of you to help me.
Thanks for your help !
[email protected]

Thanks for your help!
I must recognize that my explainations weren't really precise.
My principal bean owns a table of my inner-class type :
public class FirstBean extends EntityBean {
private SecondBean[] tabSB;
public SecondBean[] getTabSB() {...}
public void setTabSB(SecondBean[] p_tabSB) {...}
public class SecondBean {...}
So I can call a specific bean from the tab in my Servlet for another page.
But I think I have the solution and I need your advise :
I tried this :
<jsp:useBean id="FirstBean" class="<...>.FirstBean" scope="session" />
<jsp:useBean id="SecBean" beanName="<...>.FirstBean$SecondBean" type="<...>.FirstBean$SecondBean" scope="request" />
And would you believe it ? It seems to work ! But I have to test this farther to be sure. What do you think of it ?

Hi, I have quick question about use of USEBEAN tag in SP2. When I specify a scope of SESSION for the java bean, it does not keep the values that I set for variable in the bean persistent.Thanks,Sonny

Make sure that your bean is implementing the serializable interface and that
you are accessing the bean from the session with the same name.
Bryan
"Sandeep Suri" <[email protected]> wrote in message
news:[email protected]..
Hi, I have quick question about use of USEBEAN tag in SP2. When I
specify a scope of SESSION for the java bean, it does not keep the
values that I set for variable in the bean persistent.Thanks,Sonny
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WL5.1: Using JSPC with pages that include usebean tags

Hi All,
          I'm trying to get JSPC to correctly compile my JSP pages (which compile with
          no problems from within Weblogic itself) and for each page that contains a
          <userbean> tag, it seems as though java is trying to instantiate the bean as
          it turns the JSP page into a servlet.
          I can stop this happening by changing the <usebean class="foobar"/> tag to a
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          scope already, which is not the case.
          Is there anyway to tell JSPC not to instantiate the beans in the <usebean>
          tags?
          bye


Hi All,
          I'm trying to get JSPC to correctly compile my JSP pages (which compile with
          no problems from within Weblogic itself) and for each page that contains a
          <userbean> tag, it seems as though java is trying to instantiate the bean as
          it turns the JSP page into a servlet.
          I can stop this happening by changing the <usebean class="foobar"/> tag to a
          <usebean type="foobar"/>, but according to the documentation, this technique
          is only supposed to be used when the bean's object is expected to be in
          scope already, which is not the case.
          Is there anyway to tell JSPC not to instantiate the beans in the <usebean>
          tags?
          bye

Unable to use jsp:useBean tag

when I use
<jsp:useBean id="addressBean" class="AddressBean" scope="session"/>
I get the following error
Exception Details: org.apache.jasper.JasperException
Unable to compile class for JSP No Java compiler was found to compile the generated source for the JSP. This can usually be solved by copying manually $JAVA_HOME/lib/tools.jar from the JDK to the common/lib directory of the Tomcat server, followed by a Tomcat restart. If using an alternate Java compiler, please check its installation and access path.
So my question is how to use the <jsp:useBean> tag in JSC

Please see my message How to set developer's mode for oracle jsp engine.
As a very early warning of the future, this way of setting configuration paramemter in web.xml for oracle jsp engine will be deprecated in the next major version of oc4j and desupported probably later on. Yes, it is still supported in 10.1.3 and the next major version, though.

Usebean Tag

What are the advantages of usebean tags in jsp.
Is there any benefits, if i'm not using any SQl queries in JSP.
If i used Javabeans set & get methods and store them in a vector, in a web application. How far it will increase the performaance?

Its not a question of performance.
Its a question of design and maintainability.
Pages with lots of java scriptlet code mixed in with HTML are difficult to read and understand, and harder to maintain than JSPs with no scriptlet code.
The same reason for not including sql code in your JSP.
The aim is to have the SQL code in ONE place, so if it changes, then you only have to change it in one place.
If you have bits of SQL scattered through 5-6 jsp pages it becomes that much more difficult.

Need help with the jsp:useBean tag

Dear Fellow Java/JSP developers:
I am trying to use the <jsp:useBean> tag in a jsp that displays the values from a javaBean that gets populated by another class.
<%@ page contentType="text/html" pageEncoding="UTF-8"%>
<%@ page import = "java.util.ArrayList"%>
<%@ page import = "java.util.Iterator"%>
<%@ page import = "salattimes.CalendarParse" %>
<%@ page import = "salattimes.Salat" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">
<html>
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        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
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        <%=mytime.getA() %>
        <%=mytime.getB() %>
        <%=mytime.getC() %>
        <%=mytime.getD() %>
        <%=mytime.getE() %>
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</html>However, up to now, I am only able to display the values on my JSP page using the scriptlet
<% CalendarParse sTime = new CalendarParse();
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<%=mytime.getA() %>
         <%=mytime.getB() %>
         <%=mytime.getC() %>
         <%=mytime.getD() %>
         <%=mytime.getE() %>to present the values on the screen. What I would like to do is assign the object that I create to a javaBean reference declared in a <jsp:useBean> tag as follows:
<jsp:useBean id="test" scope="session" class="calendar.Time" />
        <% CalendarParse sTime = new CalendarParse();
            test = sTime.runExample();%>and then present the values stored in the bean to the JSP page as follows:
<jsp:getProperty name="test" property="a" />
        <jsp:getProperty name="test" property="b" />
        <jsp:getProperty name="test" property="c" />
        <jsp:getProperty name="test" property="d" />
        <jsp:getProperty name="test" property="e" />
        <jsp:getProperty name="test" property="f" />Is this possible? When I try the above, I get "null" as my output on the screen. When I try the first approach listed above, I get the values I am looking for. Is there a way to accomplish this using the <jsp:useBean> approach?
Thanks to all those who reply.
Sincerely;
Fayyaz

The code:
<jsp:useBean id="calendar" class="calendar.CalendarParse" scope="session"/>
<c:set var="time" value="${calendar.time}"/>Would be roughly equivalant to:
calendar.CalendarParse calendar = new calendar.CalendarParse();
Object time = calendar.getTime();I assumed that the CalendarParse object was in the calendar package because that was were your Time class was (when you used <jsp:useBean id="test" scope="session" class="calendar.Time" />"), but when I look back at your original post I see I was wrong and the use of calendar as both the incorrect package and the variable name was confusing. To make the code more similar to your original post the code should have read:
<jsp:useBean id="sTime" class="salattimes.CalendarParse"/>
<c:set var="myTime" value="${sTime.time}" scope="session"/>
${myTime.a}
${myTime.b}
${myTime.c}
etc...Here is an explanation of the parts:
         /* name of the variable */ /* fully qualified class name, package.className */
<jsp:useBean id="sTime"           class="salattimes.CalendarParse"/>
/* name of the new object from bean */ /* source of object, variable.property */    /* Scope of new object */
<c:set var="myTime"              value="${sTime.time}"             scope="session"/>
/* data to display variable.property */
${myTime.a}Where a 'property' in a bean is defined as a method in the form of getProperty(). So the 'time' property is getTime() and the 'a' property is getA().

Needless inline styles and span tags

OS: Win XP SP 2
Product: RoboHelp HTML 6
Output: WebHelp
I am finding some instances of needless inline styles and
span tags in some topics in a project. Around these problematic
instances are plenty of instances that have no problem. I used
non-problematic instances as guides for correcting the problematic
instances. Fortunately, RH hasn't overwritten any of my
corrections.
I am concerned about the insertion of needless inline styles
and span tags at two levels. First, I see them as indicators of
inconsistency. Whether the inconsistency is in myself or in RH, I
don't know (but I want to eliminate it). Second, needless code is
wasteful (esp., wastes time in code view).
Has anybody seen this before? Does anyone know or suspect a
cause?
SAMPLE 1
RH6 created: <p><span><span
style="font-weight: normal;">blah blah yaddi
yaddi</span></span></p>
I corrected: <p>blah blah yaddi yaddi</p>
SAMPLE 2
RH6 created: <p style="font-weight: normal;"><span
style="font-weight: normal;">blah blah yaddi
yaddi</span></p>
I corrected: <p>blah blah yaddi yaddi</p>
SAMPLE 3
RH6 created: <p style="font-weight: bold;"><span
style="font-weight: bold;">blah blah yaddi
yaddi</span></p>
I corrected: <p style="font-weight: bold;"><>blah
blah yaddi yaddi</p>

Some of this has to do with how users have applied styles in
WYSIWYG mode; for example, if you double click a word (which
selects the space after) and apply Bold, then later select the word
by dragging the cursor to select only the word (which doesn't
select the space after), RH will usually surround the selected
characters with "normal" span tags and often leave the bold in
place.
This same type of style formatting might have been repeatedly
done in the original form that might have been imported (Word,
Frame, etc.). So, then, if you compound the code bloat from an
imported file with additional formatting in RH, well you do the
math.
I've seen code wherein a six-word sentence might be saddled
with as many as 10-12 SPAN tags and might stretch into 6-7 lines of
code!
However, these are still flat files, not binary; you'd need a
ton of extra code to increase the aggregate file size a lot. Heck,
your graphics will usually take more room than your topics. One of
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aggregate of .gif, .jpg, and .bmp graphics exceed 4 MB. My view has
always been this: until the underlying code affects the format I
expect to see in my output, I consider extra SPAN and KADOV tags to
be nothing but white noise.
Good luck,
Leon

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Hello all
I am moving to Macbook Pro (previous gen) with Logic Studio after years of PC (feel like I’m standing on the edge of a precipice staring anxiously down!). Will be looking to use it live in our 3-piece band to run existing MIDI Files and live triggered BFD drum samples
Have decided on getting an Echo AudioFire 8 to handle the necessary Audio outs and MIDI connections and will be replacing our rather dated Korg 05R/W General MIDI module with virtual instruments / samples libraries
I am thinking that once the Bass (probably Orange Tree CoreBass samples through Kontakt 3) and Orchestration (still wide open to suggestions on that!) are done, they’ll be exported as Audio files or perhaps ‘frozen’ in Logic to ease the load on real-time processing
Here’s the query then:
*Assuming that the internal drive will be for OS and programs only, will having the sample libraries and exported audio song files on separate physical drives from each other pay dividends – particularly when considering that the audio tracks (probably no more than two or three stereo files) will be streaming whilst BFD is triggering live samples via MIDI input..? I’m wondering if the samples and audio separate drives situation will be considerable beneficial, or given the intended application, would this approach be merely over-speccing things?*
If that is thought to be the best approach, what do you believe to be the best way of hooking these up? I plan on using the FW400 port for the Echo AudioFire 8 and have ordered a Sonnet Express eSATA Card to hook up an external drive. Should any additional drive look to use the FW800 port or should I simply tag into the spare eSATA port on the Sonnet Express Card..? My concern with the latter is that a bottleneck would occur in the Express port and defeat the whole object
I would really appreciate any thoughts on this
Many thanks
Clive

My opinions:
If you're really only talking about 2-3 audio tracks per song, having them on a separate drive is not going to make that much difference. I'd recommend just using one drive for both audio and samples for now, you can always add another hard drive later if you're getting disk errors, or if you start using more audio tracks.
If you're looking for a good orchestral library, I recommend Vienna Symphonic Library Special Edition (about $500). VSL sounds great, and this particular set is much cheaper and still gives you a good amount of instruments/articulations.
If you do go with a third drive, use both eSATA ports. Even with a little bottlenecking, you should see substantially faster performance than with FW800. The data transfer rate of eSATA is over 3 times that of FW800.
Message was edited by: jdredge

UseBean tag location

I have a small login application that uses JSP pages and servlets and EJBs. The flow of the application is as follows:
login form (jsp) posts to:
servlet that calls a login method of a bean, redirects to:
logged in page (jsp) links to:
change password form (jsp) post to:
servlet that calls bean method to change password, redirects to:
logged in page.
My question:
The bean with the login method is first created on the login form with a useBean tag. This one works just fine. However the bean with the change password method cannot be found with a request.getAttribute as the other bean can be. This is true when I first create this bean on the change password form with a use bean tag. Strangly enough if I put this useBean tag on the login form (the page I run from Jdeveloper) I have no problem using the request.getAttribte method. Both beans have a scope of session.
Can any tel me why this is?
null

Thank you very much! My problem has been solved. I did not know that JBOSS or Tomcat do not support non packaged java bean any more.
Xin

(ios5 ipad bugs)I can't get changes of album art, artist, album and other tags to show up in the iPad music player, but they show up correctly in the iTunes device view. Certain random songs do not sync correctly. Wifi sync hasn't worked yet.

(ios5 ipad bugs)I can't get changes of album art, artist, album and other tags to show up in the iPad music player, but they show up correctly in the iTunes device view. Certain random songs do not sync correctly. Wifi sync hasn't worked yet.
I mostly use technology for education and professional audiovisuals and lights.
I don't sync music because I use music from at least 4 different computers. (manually mange music)
I use my iPad to play performance tracks for church and a local gospel group out of our church, Won4Christ.
I chose to buy the iPad because the laptop of one of the group members (dellxps running iTunes) was randomly losing and mixing up music and I wanted a more stable option that was bigger than my iPod touch.
I tried to add some data to music libraries that I previously added to my iPad, but the data only shows up when looking at the device in iTunes.
Wifi sync has not worked on either my laptop or desktop ( both running windows 7 enterprise 64 and newest iTunes) not really a big issue, but very annoying
When browsing through library playlist albums on the iPad, random artwork shows up on playlists with no artwork that you touch while dragging, and it does not go away until you change to another navigation tab and back.
Random songs out of hundreds that I added showed up in iTunes grayed out with a sync circle beside them. Those songs would play back okay on the iPad but were unplayable through the iTunes device view. I had to delete the songs manually through the library along with the playlist and add them again.
These seem to be major stability bugs in the "new" music app and iTunes. My only option right now seems to be to delete the songs that I want to change and re-add them with the changes already applied rather than changing the id3 tags and artwork on the existing music. I hope apple will release updates to resolve these issues.
Thank you for actually making it to the end of this manuscript of annoyances.

Just wondered if anyone had any other suggestions.

Matching opening and closing tags in MXML

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In DreamWeaver you can see the hierarchy for every HTML element, and you can click any HTML element to highlight the block inside.
I can see only icons with - and + for contract or expand the MXML blocks, but they are working wrong !

If you click the element in Outline view, it should highlight the entire tag for you. Is it not doing this in FB 4?

ConnCacheBean sample and useBean tag?

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