Using OraclePreparedStatement with DBCP Connection

问题

I'm trying to make a connection pool with the dbcp framework for my oracle server. I used this tutorial for the connection. The problem is to create a OraclePreparedStatement with this connection:

Connection oracleCon;
OraclePreparedStatement o_stmt;
String sql = "INSERT INTO T002_metadata (T002_datacitexml,T002_version, T002_active)       VALUES (?,?,?) RETURNING T002_id INTO ?";


oracleCon = ConnectionManager.ds.getConnection();

o_stmt = ((OraclePreparedStatement) oracleCon.prepareStatement(sql));

After executing this, an exception is thrown.

org.apache.commons.dbcp.DelegatingPreparedStatement cannot be cast to oracle.jdbc.OraclePreparedStatement

Is there any possibility to cast the statement?

回答1:

Not to an Oracle class, no. That's what JDBC is for. It's an API. Use java.sql.PreparedStatement only. By attempting to downcast, you violate polymorphism and break things like this, where a library is wrapping the real connection and statement to provide some additional services for you.

回答2:

I had the same problem today and solved it by changing Tomcat configuration as suggested here. I changed the context.xml file by changing the type and factory properties like this:

....
<Resource name="jdbc/dsName"
       auth="Container"
          type="oracle.jdbc.pool.OracleDataSource"
          factory="oracle.jdbc.pool.OracleDataSourceFactory"
       user="username"
       password="password"
       driverClassName="oracle.jdbc.driver.OracleDriver"
       url="jdbcurl"/>
....

also resource definition in web.xml file had to be changed

....
 <resource-ref>
    <description>Oracle datasource</description>
    <res-ref-name>jdbc/test</res-ref-name>
    <!-- <res-type>javax.sql.DataSource</res-type>-->
    <res-type>oracle.jdbc.pool.OracleDataSource</res-type>
    <res-auth>Container</res-auth>
  </resource-ref>
....

no changes have been needed in my code.

回答3:

I f you're using Oracle, you can cast your connection to OracleConnection, and then cast your prepared statement to OraclePreparedStatement. What jdbc does is upcast the Oracle objects to standard sql objects, but they are still Oracle sql objects.

来源：https://stackoverflow.com/questions/7484988/using-oraclepreparedstatement-with-dbcp-connection

标签

java

Oracle

casting

prepared-statement