FileChannel and close method
Hi all!
I have a terrible doubt, this:
Does the Filechannel close method also close the FileInputStream its connected to?
I'M USING JDK 1.4.2_08 and I have seen this bug:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4796385
Thank you very much
best regards.
Raffaele
Yes, invoking FileChannel's close method also closes the java.io class that created it.
Similar Messages
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Issue with close() method of BufferedReader class and FileInputStream class
I have written the following code to a text file, called hello,txt from Windows. Everything works fine but I am trying to figure out whether calling of close() method of aforemetioned class is appropriate or necessary thing to do.
Here are the questions:
1. Is it necessary to call close method in this senario? And why? [it seems to me that everything gets cleaned up automatically anyways at the end of each call to the method when called from main()]
2. If the answer for No.1 is yes, then in which order each close method should be called? Or, does the order of calling close method matter anyways?
3. Is the reason for why in No.1 is that because calling close method on each object is a necessary step to do when dealing with mutli-thread?
Thanks for your help in advance!
* Below is an example to clarify my questions
void readWinFile() {
File objFile = new File("hello.txt");
FileInputStream fileStream = null;
BufferedReader bfReader = null;
try {
fileStream = new FileInputStream(objFile);
bfReader = new BufferedReader(
new InputStreamReader(fileStream, "MS932"));
int tmp;
while ((tmp = bfReader.read()) != -1) {
System.out.print((char)tmpLine);
} catch (FileNotFoundException e) {
System.err.printf("File: %s Not Found @ DIR = %s",
objFile.getName(), objFile.getParent());
} catch (UnsupportedEncodingException e) {
System.err.printf("Internal failure: %s", e);
} catch (IOException e) {
System.err.printf("File: %s close failure", objFile.getName());
* } finally {*
* if (bfReader != null) {*
* try {*
* bfReader.close();*
* } catch (IOException e) {*
* e.printStackTrace();*
* if (fileStream != null) {*
* try {*
* fileStream.close();*
* } catch (IOException e) {*
* e.printStackTrace();*
}Edited by: Jay-K on Feb 14, 2010 8:50 PM
Edited by: Jay-K on Feb 14, 2010 8:52 PMHello CeciNEstPasUnProgrammeur,
Thank you for taking your time and doing all these write-up for me.
CeciNEstPasUnProgrammeur wrote:
Pretty much every native resource, most notably DB connections because those even remain open after the client process terminates. But ports or file handlers are similar; note that a JVM does not necessarily terminate just because you close your program in "extreme cases" (shared use of JVM). In an app server this is certainly never the way. And even if it does, as long as your app is running, the stuff is certainly never released.What you meant is that if my app runs on an app server, which shared the use of JVM with multiple apps, without properly closing ports or file handlers could cause JVM to keep retaining the native resource allocated for my app. In case of that, the resource leaks would occur.
On the other hand, if my app runs on an app server, which do not share the use of JVM, the leaks would be less likely to happen even if the ports or file handlers are not manually closed. (It could be a very poor design but technically I could reply on their finalizers to clean up the mess)
>
Another misconception seems to be that objects are automatically GCed the moment they run out of scope. This is not true.Is there any documentation somewhere that you could refer me to? I would like to figure out why objects are not auto-GCed when they run out of their scope.
>
And lastly, objects should not rely on their finalizers to release native resources, and should rather provide close/release methods. This is a common paradigm, and that's also why releasing the file handle won't work by simply letting the reader instance run out of scope. Nobody notifies the underlying OS.I see, so the JVM here interacts with the underlying OS to acquire sufficient native resource for its apps to run. Without explicit closing, which would make JVM not to notify underlying OS to release acquired resource. Am I on the ball here?
Thanks,
Jay -
Thanks !
Kudos always welcome for helpful postsRe: I have a VI A. I want A to call another VI B and execute. After B executes, I want it to close automatically and go back to A. Is this possible ? I tried using open reference and those methods, but I am not able to do it. Can someone help me ? Thanks !Hi Stephan ! Thanks ! I guess I explained my question not so right. I've created a customized menu and at the instance of me selecting a menu, a VI should load itself dynamically. I am using call by reference. Sometimes it works and sometimes it won't. In short, what I want to achieve is load VIs dynamically and close them dynamically once they finish executing. Thanks !
Kudos always welcome for helpful posts -
IE open and close immediately. Can't fix using many methods.
A user reports that can't use IE 8 suddenly.
His PC is Windows 7 Pro sp1 and using Internet Explorer 8.
Don't know what he did before and he ever tried restore to previous point but no help.
I've tried the following.
1. http://support.microsoft.com/kb/967896
Reset Internet Explorer to its default settings or
Uninstall and then reinstall Internet Explorer through Turning on/ off windows features.
2. Use other user like Administrator to open IE. But result is same
3. Upgrade to IE 11. Still open and close immediately only.
Repeat step 1 but still not solve.
4. Downloaded IE 11 and installed manually but it stated that IE 11 was installed. (Had turned off IE to uninstall it through Turning on/ off windows features)
Asked him to use Chrome but some websites need IE. So he must use IE too.
Please advise that how to fix it.
Hope not need to re-install OS.
Many thnaks.1. Are there any traces in Event logs?
2. Try to delete history in IE
3. Try to disable add-ons.
4. If nothing helps, analyze your system with Process Monitor and Process Explorer. Check which programs starts with Autoruns (all programs are from Sysinternals)
Regards
Milos -
What is the better way to open and close connection in bean
Hello, may i ask about the best way to open and close the connection?
At the first, the connection code is store in Conn class bean. The JSP page will call a method in Process bean to process the query and update of database. the Process bean is using th Conn to connect to database.
In my process bean, it have a method for each type of sql like select, insert, update, and delete for each tables. Each method will call the Conn to open and close the connection. The jsp page can simply call a method retrieve or update records.
However, when calling the processUpdate method, it is a method that update a group of tables base on the query result of another group of tables and calculation. If I calling the query method in the same bean file, it will open and close the connection many times (more than 1000 times). After open and close the connection several times, the connection to mySQL will be fail.
Currently, i include 2 method in Process that is only calling the Conn to open the connection and close connection. When calling the openConnection method, it will also set the boolean connected in the class to true and call Conn to open connection. When calling the closeConnection method, it will also set the boolean connected in the class to false and call Conn to close connection.
After that, i add some change to the query method which is when the connected is false, it will open the connection by calling the Conn and close the connection themself. If the connected is true, it will not call the Conn to open and close the connection because it already connected to the database.
Now, i when i calling the query method in jsp, it can open the connection and close the connection individually. When i call the processUpdate in the jsp, this method will calling the openConnection before calling the query and calling closeConnection at the end. It not only faster the process(less open and close), it also no cause the connect to mySQL fail error again. However, it also make the coding in the bean file more longer and complex.
Is there have any better solution?Use connection pooling. This will put the connection management in the hands of the webserver, not your code. Check out this post:
http://forum.java.sun.com/thread.jspa?threadID=741788&messageID=4252932#4252932 -
Open vi within vi and close the the last one
Hi all
I've searched the solution to my problem, but didn't find.
Short brief:
I have a VI that uses for authorization, then if all O.K it should open other VI("code-vi") and run it and close itself.
I saw that some people recommended , that it can be done by just putting the "code-vi" in the right place, but when I'm following this method , the authorization VI can't be closed.
the other method I tried is to put a sequence where the first stage is opening the "code-vi" with "vi server ref" and the second stage is close this VI also with "vi server ref". with this method i'm facing two problems , the first is the fact that all the vi's are within a project , and I want that the "path refernce" would be generic - I can put the folder that holdes all the files in any PC and it would run without redirecting the path.
The second problem is that I can't find the way to automaticaly run the "code-vi" when it invoked.
which files should I attach if i'm using project ?
Solved!
Go to Solution.UdiWeiss wrote:
so from your answer I can't configure it as for a VI that it is not in project -> VI properties , execution.
I'm not sure what you are trying to say here. The "Run When Opened" property for the VI doesn't care how the VI was opened, just that it was opened.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines -
[bdb bug]repeatly open and close db may cause memory leak
my test code is very simple :
char *filename = "xxx.db";
char *dbname = "xxx";
for( ; ;)
DB *dbp;
DB_TXN *txnp;
db_create(&dbp,dbenvp, 0);
dbenvp->txn_begin(dbenvp, NULL, &txnp, 0);
ret = dbp->open(dbp, txnp, filename, dbname, DB_BTREE, DB_CREATE, 0);
if(ret != 0)
printf("failed to open db:%s\n",db_strerror(ret));
return 0;
txnp->commit(txnp, 0);
dbp->close(dbp, DB_NOSYNC);
I try to run my test program for a long time opening and closing db repeatly, then use the PS command and find the RSS is increasing slowly:
ps -va
PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND
1986 pts/0 S 0:00 466 588 4999 980 0.3 -bash
2615 pts/0 R 0:01 588 2 5141 2500 0.9 ./test
after a few minutes：
ps -va
PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND
1986 pts/0 S 0:00 473 588 4999 976 0.3 -bash
2615 pts/0 R 30:02 689 2 156561 117892 46.2 ./test
I had read bdb's source code before, so i tried to debug it for about a week and found something like a bug:
If open a db with both filename and dbname, bdb will open a db handle for master db and a db handle for subdb,
both of the two handle will get an fileid by a internal api called __dbreg_get_id, however, just the subdb's id will be
return to bdb's log region by calling __dbreg_pop_id. It leads to a id leak if I tried to open and close the db
repeatly, as a result， __dbreg_add_dbentry will call realloc repeatly to enlarge the dbentry area, this seens to be
the reason for RSS increasing.
Is it not a BUG?
sorry for my pool english :)
Edited by: user9222236 on 2010-2-25 下午10:38I have tested my program using Oracle Berkeley DB release 4.8.26 and 4.7.25 in redhat 9.0 (Kernel 2.4.20-8smp on an i686) and AIX Version 5.
The problem is easy to be reproduced by calling the open method of db handle with both filename and dbname being specified and calling the close method.
My program is very simple:
#include <stdlib.h>
#include <stdio.h>
#include <sys/time.h>
#include "db.h"
int main(int argc, char * argv[])
int ret, count;
DB_ENV *dbenvp;
char * filename = "test.dbf";
char * dbname = "test";
db_env_create(&dbenvp, 0);
dbenvp->open(dbenvp, "/home/bdb/code/test/env",DB_CREATE|DB_INIT_LOCK|DB_INIT_LOG|DB_INIT_TXN|DB_INIT_MPOOL, 0);
for(count = 0 ; count < 10000000 ; count++)
DB *dbp;
DB_TXN *txnp;
db_create(&dbp,dbenvp, 0);
dbenvp->txn_begin(dbenvp, NULL, &txnp, 0);
ret = dbp->open(dbp, txnp, filename, dbname, DB_BTREE, DB_CREATE, 0);
if(ret != 0)
printf("failed to open db:%s\n",db_strerror(ret));
return 0;
txnp->commit(txnp, 0);
dbp->close(dbp, DB_NOSYNC);
dbenvp->close(dbenvp, 0);
return 0;
DB_CONFIG is like below:
set_cachesize 0 20000 0
set_flags db_auto_commit
set_flags db_txn_nosync
set_flags db_log_inmemory
set_lk_detect db_lock_minlocks
Edited by: user9222236 on 2010-2-28 下午5:42
Edited by: user9222236 on 2010-2-28 下午5:45 -
Collapsible Panels - Links to open one, and close others
Hi,
I am new to Dreamweaver and have been creating my site by
learning as I go along. I have already read through all the other
related topics associated with Collapsible Panels on this blog and
have still not found an answer. I have been able to open and close
Collapsible Panels by using links - but unfortunately, I need more
than just opening and closing.
On my site i have approximately 5 pages, all with the same
header and Menu bar. The Information (that i have presented in
numerous Collapsible Panels) does however vary from page to page.
What I need to try and figure out is:
How can I open one collapsible panel and close all others? I
have seen the one example which leads to my next question:
How can I group Panels? Some examples of how to open one and
close all others use this grouping. Is there any other way of
opening one and closing all others without grouping?
Lastly, is it possible to set up a link that can be viewed on
one page which when clicked opens the relevant page and collapsible
panel? i.e. on my About Us page there is a link (using the Menu
bar) for one of my several services on the services drop down menu
(but services is on a different page with the same setup). When a
viewer clicks on the specific service, is it possible to get the
site to open the services page, and open the relevant collapsible
panel (with all other Panels closed)?
Any assistance would be greatly appreciated - I have been
searching for days now and cannot seem to find any
answers/directions in laymans terms.
Kind regards,
Johnwlsjoh013 wrote:
> Hi,
>
> I am new to Dreamweaver and have been creating my site
by learning as I go
> along. I have already read through all the other related
topics associated
> with Collapsible Panels on this blog and have still not
found an answer. I
> have been able to open and close Collapsible Panels by
using links - but
> unfortunately, I need more than just opening and
closing.
>
> On my site i have approximately 5 pages, all with the
same header and Menu
> bar. The Information (that i have presented in numerous
Collapsible Panels)
> does however vary from page to page. What I need to try
and figure out is:
>
> How can I open one collapsible panel and close all
others? I have seen the one
> example which leads to my next question:
This page has an example that has a link that can open and
close a panel:
http://labs.adobe.com/technologies/spry/samples/collapsiblepanel/collapsible_panel_sample. htm
One way to do this would be to have a single link that would
open one of your panels using the code, but then add to it code
that closes each of the other panels, for example:
<a href="#"
onclick="CollapsiblePanel4.open();CollapsiblePanel5.close();CollapsiblePanel6.close();">O pen
4, close 5 and 6</a>
To make this work, you'll need to look that the panel
constructors at the bottom of your page and make sure to match up
the panel variable names i.e. "var CollapsiblePanel1 =...." the
variable is CollapsiblePanel1.
You could also write a function that gathers together the
various panels you have on the page and then pass to it only the
panel that you want kept open. For now, though, it might be best to
use the above method, given your expertise. And taking that even
further, you could apply the function call unobtrusively. Both the
function call and the unobtrusive part you can work on later to get
this working for now.
> How can I group Panels? Some examples of how to open one
and close all others
> use this grouping. Is there any other way of opening one
and closing all
> others without grouping?
This is a little confusing, on one hand you ask about how to
group, but then ask how not to group. There is a concept of a
collapsible panel group:
http://labs.adobe.com/technologies/spry/samples/collapsiblepanel/CollapsiblePanelGroupSamp le.html
But there is another type of group, that may be more what
you're looking for, and that's an Accordion panel, which is similar
to the collapsible panel group, with the exception that it can only
have one panel open at a time.
> Lastly, is it possible to set up a link that can be
viewed on one page which
> when clicked opens the relevant page and collapsible
panel? i.e. on my About Us
> page there is a link (using the Menu bar) for one of my
several services on the
> services drop down menu (but services is on a different
page with the same
> setup). When a viewer clicks on the specific service, is
it possible to get
> the site to open the services page, and open the
relevant collapsible panel
> (with all other Panels closed)?
Probably the easiest way to do this particular one would be
to make sure that you have all of the panels set to be closed when
the page loads, and then take a look at the code for the last
example on this page:
http://labs.adobe.com/technologies/spry/samples/utils/URLUtilsSample.html
That example uses a tabbed panel, but the concept is the
same, use a URL parameter to determine what to show. You'll need to
link in the SpryURLUtils file in the Spry download package (look in
the includes folder):
http://labs.adobe.com/technologies/spry/home.html
Essentially, your link will look similar to:
sample.html?panel=1
Then your code could look something like:
var params = Spry.Utils.getLocationParamsAsObject();
var CollapsiblePanel1 = new
Spry.Widget.CollapsiblePanel("CollapsiblePanel1",
{contentIsOpen:(params.panel==1 )} );
var CollapsiblePanel2 = new
Spry.Widget.CollapsiblePanel("CollapsiblePanel2",
{contentIsOpen:(params.panel==2 )} );
Basically what this is doing is creating an object from the
URL parameters. Then for each of the panels the constructor has
code that determines whether or not to expand the panel when the
page loads. So it checks the value of params.panel to see if it
matches 1 (for the first one), if it does, then that means that
contentIsOpen is set to true, if it is some other number or is not
present at all, then that means that the panel is closed. This
would then be repeated down the line for how ever many panels you
want to operate like that.
Danilo Celic
|
http://blog.extensioneering.com/
| WebAssist Extensioneer
| Adobe Community Expert -
Automatically open, save and close excel?
I need import data from Excel to SQL.
Now, I use tSQL to directly read the excel files and transform to the SQL table.
As the user Excel is not a good format for SQL to read, I need use formula to transform the excel to be a SQL readable format.
Now, I add a sheet to copy the data from the sheet which user input the data and then ask the user to copy the excel to a specific location for import.
However, this will make the data in the excel double and result a large excel file.
I am thinking if it is possible to create a excel to use formula to copy the data from another excel.
Then, I need find some method to open that excel, let the content refresh from the source excel, save and close it.
Then I can directly use this excel for data import.
Is there any simple way to do so? I don't know marco much...
IvanNo formula could do this (Automatically open, save and close excel).
You need to recode a marco or write a macro. Why donot you ask in msdn?
http://social.msdn.microsoft.com/Forums/en-US/home?forum=exceldev&filter=alltypes&sort=lastpostdesc
example:
Sub auto_open()
Application.OnTime Now + TimeValue("00:01:00"), "wswx"
End Sub
Sub
wswx() If Not ThisWorkbook.Saved
Then ThisWorkbook.Save
ThisWorkbook.Close
End Sub
KR -
Why should you explicitly open and close shared variable connections?
I'm looking into switching over from the old Datasocket API to the new Shared Variable API for programmatic access to shared variables, and I noticed that LV doesn't seem to have any problems executing Shared Variable Reads & Writes without first opening the connection explicitly. That is, I can just drop in a shared varaible Read VI, wire a constant to the refnum input, and it will work. I'm wondering, then, what benefits are offered by explicitly opening the conenction ahead of time...?
I guess I could see some cases where you want to open all necessary connections in an initialization state of a top-level state machine, particularly if you want to use the "Open & Verify Connection"---so you could jump straight to an error case if any connections fail. But other than that, why else might one want to explicitly open the connections.
And, along those lines, are there any problems with implicitly opening the connections? One reason why I am hesitant to open them explicitly is because for one of our applications, we need to be able to dynamically switch from one variable to another at runtime. It would be nice to just switch the variable refnum (wired to the input of the Read function), without having to manually close out the old connection and open a new one. A quick prototype of this seems to work. But am I shooting myself in the foot by doing so?
Thanks in advance.I'd expect there's a very small number of people at NI that would know the answer to the detail you're asking for. But, let's try to extrapolate from this rather old post to see if we can understand what they're forming their impression on.
The shared variable has to have some sort of reference going on in the background. It looks like they're calling this a connection. It's how LabVIEW knows where to find this variable on the network. We can also see this reference certainly exists if we're opening/closing the reference in the explicit method. You see the connection as just a string referencing the variable by URL. This "reference" has to be stored somewhere. No matter how we're looking at this, we're aware there's a reference of some sort stored.
Now, we'd want to look at what would cause this reference to go away. If you open/close explicitly, it's easy to see it goes away at the close. If it's implicit, when would it make sense to close it out? The VI can't be expected to guess where it's done being referenced and close it out. This puts us into a situation where the soonest it could close is when the VI ends. From my experience, references tend to be wiped when you close out LabVIEW. It's this kind of idea that makes the FGV possible. I wouldn't be surprised by Morgan's claim here.
If we look at scalability, you're talking about two different topics. You're talking about adding an extra open, close, read, etc rather than just a few wires. That certainly would look a mess. In terms of the dynamic swap that was being discussed, we wouldn't be adding all of those. The concern would be if enough connections were opened it'd start to behave similar to a memory leak. This could be something that works with a smaller number of variables. If you continue to scale, it becomes problematic. This is why they suggest it's not scalable.
To your questions:
Does LV allocate some kind of session in memory using that string as a lookup?
It would HAVE to allocate some memory to hold that string. Otherwise, it'd be pointless to even have the reference.
Does it reuse that session if other parts of the application reference the same variable, or does it create a unique session for each referencing call to "Read Variable.vi"?
I would expect this to be "it depends." With the implicit method, I would expect it to open a new reference in each point it isn't wired. This is similar to int x,y = 5; x and y share the same value but are their own unique memory location. If you wire the reference to the other points, it should use the same reference. This would make more sense to me than the program seeking out any other potential usage of the variable in the application to see if there's already a reference open. I could be wrong, though.
And what resources does this "connection" actually represent?
At best, this is just the string. At worst, it's the string and the TCP socket. I'd lean towards the first. Opening and closing sockets should be relatively easy in most applications. But, it also wouldn't surprise me if it holds the socket.
I'm sure others have a better understanding than I do. But, that's what I'd expect for anything you've asked. -
Is an Open and Close Stmt of some kind mandatory for BDC?
If so what is the quickest way to code it? I am restricting a batch in an interface. In the same interface I unrestrict but it does not work. I am using BDC. I am thinking I may be missing some syntax for open close in my BDC.
Thank-youWith out open and close Group function it is not possible to create the sessioon and not possible to use the BDC session method. only when you open the session then only you should insert and close the Group.
CALL FUNCTION 'BDC_OPEN_GROUP'.
if Open = 'X'.
CALL FUNCTION 'BDC_INSERT'.
endif.
if open = 'X'.
CALL FUNCTIOn 'BDC_CLOSE_GROUP'.
endif. -
Totally out of the blue, my trackpad is presenting a "bug". Every time that I try to open and close my mission control, or in the moments that I move / roll up and downs the Applications Screen, my Mac freezes for less than a second.
It never suffered any damage (NEVER!)! I am feeling very frustrated because I have no idea about what could cause such problem.
My MacBook Air is running OS X 10.9.5.
Any help will be very welcome!Well, it all really depends on the custom program and how it was written. Does it have an ActiveX interface? If it does, than that's the easiest way to go. If you put an automation refnum on the fron panel, you can right click and it and choose Select ActiveX Class>Browse. The browser will list all of the ActiveX type libraries that are registered on your system. If you can find one that refers to your custom program, then you should be able to use it's methods and properties to control. If it does not have an ActiveX interface, then things get much more difficult.
-
ActiveX to open and close application
I am new to LV (have 6.1). What I want to do is open up an external application when a certain LV action is performed (like a boolean button, or something similar), minimize the LV application (will use Application Builder here), and close it when a different LV action is taken (a different boolean button, or something similar). I need to keep the LV app running while this other app runs so I can perform other minor tasks simultaneously. The external app needs to close so the LV app can regain control of the serial ports, among other things.
From what I've gathered so far on LV and ActiveX, there's a set of things one can do. Lots of stuff with dialog boxes, and other things like that built into Microsoft, and MS programs (Excel being quite popular). This external program is a custom program.
Any ideas?Well, it all really depends on the custom program and how it was written. Does it have an ActiveX interface? If it does, than that's the easiest way to go. If you put an automation refnum on the fron panel, you can right click and it and choose Select ActiveX Class>Browse. The browser will list all of the ActiveX type libraries that are registered on your system. If you can find one that refers to your custom program, then you should be able to use it's methods and properties to control. If it does not have an ActiveX interface, then things get much more difficult.
-
How to handle the "cancel" button and "close" icon of a popup ?
Hi,
I have a popup with "cancel button" and "close icon"(on the top right corner of the popup), I want the same operations to be performed on clicking of any of these two components.
Is there a way to handle such situation ?
I read about 2 cases to look into this but they didn't work too well for me.
1. I read about the "popcancellistener" but that listener is called whenever the popup closes, so suppose I have an "ok button" on the popup to create a record, after the record is created, the popup closes and goes into the "popcancellistener", now the question is "how do we know if it came there because of the 'ok button' or 'some other event'".
2. I even checked the "DialogListener", now I'm able to distinguish between the 'OK' and 'CANCEL' button in the dialoglistener using the "Dialog.Outcome.ok/cancel", but when a user clicks on the close icon, we do not enter the "DialogListener" at all, so in this case "how do we handle the close icon click event"
Do let me know if you need any more information from my side.
Thanks for the help in advance.The following mechanism responds to any of the following events: <Esc> key, Close icon ('x'), Cancel button
JavaScript part:
function popupClosedListener(event){
var source = event.getSource();
var popupId = source.getClientId();
var params = {};
params['popupId'] = popupId;
var type = "serverPopupClosed";
var immediate = true;
AdfCustomEvent.queue(source, type, params, immediate);
}JSF part:
<af:popup ....>
<af:clientListener method="popupClosedListener"
type="popupClosed"/>
<af:serverListener type="serverPopupClosed"
method="#{myBean.serverPopupClosedMetod}"/>
</af:popup>Finally, Java part:
public void serverPopupClosedMetod(ClientEvent event){
} -
When to open and close database connection
im trying to connect to a oracle database using servlets
when should i open and close the connection
it works fine when i do both in the doPost() method
but when i tried to open connection in init() methd .. it doesnt seem to work
what should i do...
the connection is initialised in the init() method but is null in the doPost() method" im trying to connect to a oracle database using servlets
when should i open and close the connection
it works fine when i do both in the doPost() method
but when i tried to open connection in init() methd .. it doesnt seem to work
what should i do...
the connection is initialised in the init() method but is null in the doPost() method"
1:
without seeing the code i would say the the connection is null
because you are storing it as a servlet class variable which is
not thread safe.
2:
The best way to do it using connection pooling
detailed docs on the tomcat website
3:
if you are not using connection pooling, then
open and close the connection in the do* method
or
use init() to place the connection in the servletconfig
and close in destroy() and use synching to access
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