Struts, ''dataSource'' is null

Hello. I am working on a small projest using Struts and defining JNDI to get datasource. In the login page, when 'submit' is clicked, I get error messages:

WARN : 2007-10-01 13:52:34,658 [http-8080-Processor25] RequestProcessor - Unhandled Exception thrown: class java.lang.NullPointerException
ERROR: 2007-10-01 13:52:34,758 [http-8080-Processor25] [action] - Servlet.service() for servlet action threw exception
java.lang.NullPointerException
at com.swlAdminJ.bo.AdminLoginBO.findByName(AdminLoginBO.java:31)
at com.swlAdminJ.action.login.LoginSubmitAction.execute(LoginSubmitAction.java:32)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
.......

I found that the 'dataSource' in 'findByName(String aName, String aPwd)' of class 'AdminLoginBO' was null. I can't figure out why this dataSource is null. Does anyone have idea what causes the error? Thanks in advance.

Here are part of the code. I use Tomcat 5.5, struts 1.1, mysql 5.0 and Eclipse. 'mysql-connector-java-5.0.7-bin.jar' is under '..\Tomcat5.5\common\lib'.

context.xml under 'WebRoot\META-INF' is:
<?xml version="1.0" encoding="UTF-8"?>
<Context >
<Resource
auth="Container"
description="DB Connection"
name="jdbc/myDataSource"
type="javax.sql.DataSource"
driverClassName="com.mysql.jdbc.Driver"
maxIdle="2"
maxWait="5000"
username="root"
password="root"
url="jdbc:mysql://localhost:3306/my_db?relaxAutoCommit=true"
validationQuery="select 1"
maxActive="4"/>
<WatchedResource>WEB-INF/web.xml</WatchedResource>
<WatchedResource>META-INF/context.xml</WatchedResource>
</Context>

---------------------
web.xml (part of it)
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/myDataSource</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>

<servlet>
.....
</servlet>
</web-app>
-----------------
Login action class (when 'submit'button is clicked, this one is executed):

public class LoginSubmitAction extends Action
{
public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)
throws Exception
{

ActionForward returnForward = null;
AdminLoginBO curAdminBO = AdminLoginBO.getInstance();

String userId = (String)((DynaValidatorForm)form).get("userId");
String pwd = (String)((DynaValidatorForm)form).get("password");

AdminLogin curAdmin = curAdminBO.findByName(userId, pwd);

ActionMessages errors = new ActionMessages();
HttpSession session = request.getSession(true);

if(curAdmin != null)
{
session.setAttribute("adminLogin", curAdmin);

returnForward = mapping.findForward("success");
}
else
....
}
}

--------------
AdminLoginBO.java (part of it)

public class AdminLoginBO extends BaseLinkBO
{
private static DataSource dataSource;

AdminLoginBO(DataSource dataSource)
{
super(dataSource);
}

AdminLoginBO()
{
super();
}

public AdminLogin findByName(String aName, String aPwd)
throws EntityNotFoundException, SQLException
{
Connection conn = dataSource.getConnection();
try
{
AdminLogin curAdmin = (new AdminLoginDAO(conn)).findByName(aName, aPwd);
conn.commit();
return curAdmin;
} catch (EntityNotFoundException e) {
conn.rollback();
throw e;
} catch (SQLException e) {
conn.rollback();
throw e;
} finally {
conn.close();
}
}
....
}

--------------------
BaseLinkBO.java (part of it)

public abstract class BaseLinkBO
{
protected final DataSource dataSource;

protected BaseLinkBO(DataSource dataSource)
{
this.dataSource = dataSource;
}

protected BaseLinkBO()
{
this.dataSource = ServiceLocator.getInstance().getDataSource();
}

......

}

-----------
ServiceLocator.java

public class ServiceLocator
{

private static ServiceLocator instance;
private DataSource dataSource;

static {
instance = new ServiceLocator();
}

private ServiceLocator () {
Context context = null;

try {
context = new InitialContext();
dataSource = (DataSource) context.lookup("java:/comp/env/jdbc/myDataSource");
}
catch (NamingException e) {
System.out.println(e.toString());
}
}

public static ServiceLocator getInstance() {
return instance;
}

public DataSource getDataSource() {
return dataSource;
}

}
[ October 01, 2007: Message edited by: northcloud ]

"northcloud", please check your private messages for an important message.

Please use code tags in the future!

Is the private static dataSource variable hiding the one in the superclass (BaseLinkBO)?

Thank you, Carol Enderlin. This is my mistake (I didn't notice it, so silly). Once I take off 'private static DataSource dataSource;' from class AdminLoginBO, it works. Thank you again. I am sorry I didn't use 'code' tag. I won't forget it for sure.

Originally posted by Carol Enderlin:
Please use code tags in the future!

public class AdminLoginBO extends BaseLinkBO { private static DataSource dataSource; ... public abstract class BaseLinkBO { protected final DataSource dataSource;

Is the private static dataSource variable hiding the one in the superclass (BaseLinkBO)?

"northcloud", I see that you have read my message regarding adjusting your display name to meet JavaRanch standards, but have ignored it. This is not optional. Please take a look at the JavaRanch Naming Policy and adjust your display name to match it prior to your next post.

Your display name must be a first and a last name separated by a space character, and must not be obviously fictitious.

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bear
JavaRanch Sheriff
[ October 02, 2007: Message edited by: Bear Bibeault ]