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Struts & Hibernate
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| | | DB Connection prob | DB Connection prob 2007-03-20 - By Graeme McLaren
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Hi there Richard, thank you for your reply. I'll give the final keyword a
go. With respect to:
>If this is so, your application is not going to be thread-safe b/c the
>connection is static and can be used by different threads. If this is for a
>web application, you should use a connection pool and a datasource
I have been doing a java course and this is my first web app outwith the
course material (thread safe connections have never been mentioned in the
course). I don't know anything about connection pools/datasources where can
I find a good tutorial or good newbie info on this?
What problems will be be caused by using the non thread safe connection as
it is at the moment? I'm thinking performance problems.
Thank you again for your reply.
Graeme :)
>From: Richard Yee <ryee@(protected)>
>Reply-To: A mailing list about Java Server Pages specification and
>reference <JSP-INTEREST@(protected)>
>To: JSP-INTEREST@(protected)
>Subject: Re: DB Connection prob
>Date: Mon, 19 Mar 2007 21:44:14 -0700
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>Graeme,
>Since you mention that you are using a deployment descriptor, I am
>assuming this is for a web application. If this is so, your application
>is not going to be thread-safe b/c the connection is static and can be
>used by different threads. If this is for a web application, you should
>use a connection pool and a datasource. In your current problem, your
>variables should not be final.
>
>-Richard
>
>Graeme McLaren wrote:
>>Hi all, I have a prob connecting to my Oracle DB. I have a class called
>>"DBConnection" and have various setter methods which set values found
>>in the
>>deployment descriptor, for example:
>>
>> public static void setDriver (String val) {
>> driver = val;
>> System.out.println("driver 2= "+driver); // I get the value
>>displayed here so all is good at this point
>>}
>>
>>I then have a getConnection method within this class:
>>
>>public static Connection getConnection(){
>> try{
>> Class.forName( driver ); // load the JDBC "driver" class
>> connection = DriverManager.getConnection( dbURL, username,
>>password );
>>// get connection
>>
>> /*
>> more code here
>> */
>>
>>} // end of getConnection
>>
>>
>>
>>When I try to call getConnection() I get a nullpointerexception at
>>Class.forName( driver ); as "driver" is set to null, why is this when the
>>setter method sets the value?
>>
>>All variables are declared set to null and are static so they should
>>be able
>>to be set by the setter method shouldn't they? Just thinking about it
>>now
>>I'm thinking that when the variables are initialised to "null" that is
>>them
>>set and cannot be changed because they are static (and final), would
>>that be
>>right?
>>
>>How should I fix this?
>>
>>
>>Cheers
>>
>>Graeme :)
>>
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>>
>
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