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
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