org.apache.tomcat.dbcp.dbcp.BasicDataSource cannot be cast to net.sourceforge.jtds.jdbcx.JtdsDataSource

Question

Trying to connect to a (local) SQL database using jTDS JDBC drivers.

JAVA CODE

private JtdsDataSource dataSource = null;

public Connection getConnection() throws SQLException, NamingException {
        ...
        Context initContext = new InitialContext();
        dataSource = (JtdsDataSource) initContext.lookup("java:comp/env/jdbc/postcodes");
        conn = dataSource.getConnection();
                ...
    }

CONTEXT.XML

<?xml version="1.0" encoding="UTF-8"?>
<Context>
    <Resource name="jdbc/postcodes" 
              auth="Container"
              type="javax.sql.DataSource" 
              username="user" 
              password="pass"
              driverClassName="net.sourceforge.jtds.jdbcx.JtdsDataSource"
              url="jdbc:jtds:sqlserver://localhost:1433/AUSPostcodes"
              validationQuery="select 1"
              maxActive="10" 
              maxIdle="4"/>
</Context>

When I run this on tomcat, get the following error....

java.lang.ClassCastException: org.apache.tomcat.dbcp.dbcp.BasicDataSource cannot be cast to net.sourceforge.jtds.jdbcx.JtdsDataSource

Would appreciate some help with this.

Thanks in advance.

Answer 1

Tomcat doesn't give you access to a JtdsDataSource directly. It only uses that datasource to populate its internal DBCP datasource. When you use JNDI to ask for a datasource, you get the DBCP datasource.

BTW: There is (usually) no reason why you would cast to any other interface than javax.sql.DataSource. The solution therefor is to cast to that interface (javax.sql.DataSource).