Hi, Sorry I was messing up my code by making several changes. If I add that statement, I get the following SQL exception is generated Cannot create JDBC driver of class '' for connect URL 'null'. Any idea about what corrections I need to make.
Avinash Arora -----Original Message----- From: Daxin Zuo [mailto:[EMAIL PROTECTED] Sent: Tuesday, May 04, 2004 4:29 PM To: Tomcat Users List Subject: RE: DB connection pool problem You have to add con = dataSource.getConnection(); after dataSource = (DataSource)ctx.lookup("jdbc/conversion"); -----Original Message----- From: Arora, Avinash [mailto:[EMAIL PROTECTED] Sent: Tuesday, May 04, 2004 3:54 PM To: David Smith; Tomcat Users List Subject: RE: DB connection pool problem Sorry for creating the confusion. Actually I was seeing the connection object to be null for long time. But at last moment I made those silly changes to present it in a better way. Sorry about it. But now I printing the connection object and finding it to be null. I cannot understand, the reason for connection object to be null, even when datasource object is not null. Is it because that I am not able to connect to database? If yes what could be the reason. If I specify the attributes, using Direct JDBC by using Class.forName() and DriverManager.getConnection(), I can connect to data base and read all the values. But the problem comes when I use Connection pooling. Where shuld I look for correction?? ------------------------------------------------------------------ Part of my code and JSP o/p ----------------------------------------------------------------- public LinkedList selectCP(){ LinkedList ll = new LinkedList(); Connection con = null; Statement stmt = null; ResultSet rs = null; DataSource dataSource = null; try{ Context init = new InitialContext(); Context ctx = (Context) init.lookup("java:comp/env"); dataSource = (DataSource)ctx.lookup("jdbc/conversion"); ll.add("dataSource object is"); ll.add(dataSource); } catch(NamingException e){ System.out.println("Exception thrown is"+e.getMessage()); ll.add("Naming Exception thrown"); } finally{ if(dataSource == null){ ll.add("DataSource object is null"); return ll; } else{ ll.add("Data source object is not null"); } } try{ ll.add("Inside try."); ll.add("con is"); ll.add(con); if(con == null){ ll.add("Inside try. Connection object found to be null"); ll.add(con); return ll; } else{ ll.add("Connection object inside else is"); ll.add(con); } } } catch(SQLException e) { System.err.println("SQL EXCEPTION"+e.getMessage()); ll.add("SQL Exception "); ll.add(e.getMessage()); } catch(Exception e) { System.err.println(" class not found exception"+e.getMessage()); ll.add("Exception generated:"); ll.add(e.getMessage()); } finally{ if(con == null) ll.add("Connection object is null"); } try{ stmt.close(); } catch(Exception e){} try{ rs.close(); } catch(Exception e){} try{ con.close(); } catch(Exception e){} return ll; } ---------------------------O/P------------------------------------------ --- I am pasting the ll obtained on browser-- [dataSource object is, [EMAIL PROTECTED], Data source object is not null, Inside try., con is, null, Inside try. Connection object found to be null, null, Connection object is null] -----Original Message----- From: David Smith [mailto:[EMAIL PROTECTED] Sent: Tuesday, May 04, 2004 1:35 PM To: Tomcat Users List Subject: Re: DB connection pool problem Sorry about the last post. It's been a looonnng day and I didn't read it very well :-(. From what I see, you're comparing conn to null before even attempting to get a connection. Try comparing dataSource to null instead of conn in the second catch block. Then do dataSource.getConnection() if dataSource != null. --David David Smith wrote: > I'm a bit confused on your code: > > try{ > // load the driver class file > //Class.forName("com.mysql.jdbc.Driver").newInstance(); > //establishing the connection > if(con == null){ > ll.add("Inside 1st try. Connection object found to be > null"); > > > Why are you doing a Class.forName call after getting a datasource > object? I think you're mixing incompatible database access methods. > Try doing dataSource.getConnection() after getting a valid datasource > instead. You'll be happier with the result. Take a look at the > javadocs for javax.sql.DataSource for more info. > > --David > > Arora, Avinash wrote: > >> Hi friends, >> Thanks for your previous feedback. After adding several >> logging statements in my code, I have found that connection object is >> null. But dataSource object is not null. What can be reason for it?? >> Here is how I use it in my code-- >> public LinkedList testFunction(){ >> LinkedList ll = null; Connection con = null; >> Statement stmt = null; >> ResultSet rs = null; >> DataSource dataSource = null; >> try{ >> Context init = new InitialContext(); >> Context ctx = (Context) init.lookup("java:comp/env"); >> dataSource = (DataSource)ctx.lookup("jdbc/conversion"); >> ll.add("dataSource object is"); >> ll.add(dataSource); >> } >> catch(NamingException e){ >> System.out.println("Exception thrown is"+e.getMessage()); >> ll.add("Naming Exception thrown"); >> } finally{ >> if(dataSource == null){ >> >> ll.add("DataSource object is null"); >> return ll; >> } >> else{ >> ll.add("Data source object is not null"); >> // return ll; >> } >> } >> try{ >> // load the driver class file >> //Class.forName("com.mysql.jdbc.Driver").newInstance(); >> //establishing the connection >> if(con == null){ >> ll.add("Inside 1st try. Connection object found to be >> null"); >> } >> else{ >> ll.add("Inside 1st try. Connection object is not nul"); >> con = dataSource.getConnection(); >> stmt = con.createStatement(); >> .... >> } >> finally{ >> if(con == null){ >> ll.add("Connection object is null"); >> // return ll; >> } >> ----------------------Here is the output that I can see on my jsp page, >> where I try to print out the linklist obtained from the function above. >> >> elements of link list read from database are -[dataSource object is, >> [EMAIL PROTECTED], Data source object is >> not null, Inside 1st try. Connection object found to be null, Connection >> object is null] >> >> >> >> >> Thanks. >> Avinash Arora >> >> >> -----Original Message----- >> From: Daxin Zuo [mailto:[EMAIL PROTECTED] Sent: Monday, May 03, >> 2004 3:34 PM >> To: Tomcat Users List >> Subject: RE: DB connection pool problem >> >> I have just created a "pool" -- I hope it is really a pool. I used >> jtds >> jdbc driver to MS SQL Server on Windows. You may find some thing >> similar. >> Holp it helps. >> >> 1) bellow is the text in tomcat\conf\server.xml >> <GlobalNamingResources> >> <Resource name="jdbc/DirectSQL" auth="Container" >> type="javax.sql.DataSource"/> >> <ResourceParams name="jdbc/DirectSQL"> >> <parameter> >> <name>factory</name> >> <value>org.apache.commons.dbcp.BasicDataSourceFactory</value> >> </parameter> >> >> <parameter> >> <name>maxActive</name> >> <value>255</value> >> </parameter> >> <parameter> >> <name>maxIdle</name> >> <value>10</value> >> </parameter> >> <parameter> >> <name>maxWait</name> >> <value>10000</value> >> </parameter> >> <parameter> >> <name>username</name> >> <value>user1</value> >> </parameter> >> <parameter> >> <name>password</name> >> <value>passwd1</value> >> </parameter> >> <parameter> >> <name>driverClassName</name> >> <value>net.sourceforge.jtds.jdbc.Driver</value> >> </parameter> >> <parameter> >> <name>url</name> >> <value>jdbc:jtds:sqlserver://serverName:1433</value> >> </parameter> >> </ResourceParams> >> ... >> >> 2) bellow is the text in tomcat\conf\Catalina\localhost\ROOT.XML --I >> create >> this file by myself >> <Context path="" docBase="ROOT" debug="0" privileged="true"> >> >> <!-- Link to the user database using dbc:jtds:sqlserver --> >> <ResourceLink name="jdbc/DirectSQL" global="jdbc/DirectSQL" >> type="javax.sql.DataSource"/> >> </Context> >> This "name" is used in Java code. "global" is the name in xml file. they >> can >> be different. >> >> 3) my test jsp file is in \tomcat\webapps\ROOT\zuo\ >> >> Context ctx = new InitialContext(); >> if (ctx == null) { >> throw new Exception("Boom - No Context"); >> } >> DataSource ds = (DataSource) >> ctx.lookup("java:comp/env/jdbc/DirectSQL"); >> if (ds != null) >> con = ds.getConnection(); >> if (con != null){ >> str = "select * from myTable"; >> pStateSearch = con.prepareStatement(str, >> ResultSet.TYPE_SCROLL_SENSITIVE, >> ResultSet.CONCUR_READ_ONLY ); >> rs = pStateSearch.executeQuery(); >> .... >> >> That's all. >> >> -----Original Message----- >> From: Arora, Avinash [mailto:[EMAIL PROTECTED] >> Sent: Monday, May 03, 2004 3:10 PM >> To: Tomcat Users List >> Subject: DB connection pool problem >> >> >> Hi, >> I am also having the problem with the connection pools. Since I am >> writing an application first time by using connection pools, I created a >> test application DBTest. I edited my server.xml and web.xml (of my >> application in following way-- >> #added to server.xml >> <Context path="/DBTest" docBase="DBTest" debug="0" >> reloadable="true"> >> <ResourceParams name="jdbc/conversion"> >> <parameter> >> <name>username</name> >> <value>ROOT</value> >> </parameter> >> <parameter> >> <name>password</name> >> <value>PASSWORD</value> >> </parameter> >> <parameter> >> <name>driverClassName</name> >> <value>com.mysql.jdbc.Driver</value> >> </parameter> >> <parameter> >> <name>url</name> >> <value>jdbc:mysql://localhost/DB</value> >> </parameter> >> </ResourceParams> >> </Context> >> >> #web.xml >> <web-app> >> <description>MySQL Test App</description> >> <resource-ref> >> <res-ref-name>jdbc/conversion</res-ref-name> >> <res-type>javax.sql.DataSource</res-type> >> <res-auth>Container</res-auth> >> </resource-ref> >> </web-app> >> And I added the following statements to my Java class, (which works >> fine, when I use the connection objects by hardcoding the username and >> db).-- >> >> Context init = new InitialContext(); >> Context ctx = (Context) init.lookup("java:comp/env"); >> DataSource dataSource = (DataSource)ctx.lookup("jdbc/conversion"); >> >> But even after, making these changes, I cannot read any thing from >> database. I was wondering what more changes I need to made. I also tried >> to run my JAVA class (DAO) from command line, but I get the following >> exception-- >> >> Need to specify class name in environment or system property, or as an >> applet parameter, or in an application resource file: >> java.naming.factory.initial >> >> I tried to print outs the place where exception occurs in my code and >> found that exception occurs at >> dataSource = (DataSource)ctx.lookup("jdbc/conversion"); >> >> Can any body please comment on whats going on wrong? When I run from >> command line, is tomcat used, I don't think so? So where is the problem? >> Any ideas?? >> Avinash Arora >> >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> >> >> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
