The following Java code illustrates how to use True Cache with applications that use an object-relational mapping (ORM) framework.

This is another example of maintaining only one logical connection to a database application service running on the primary database and letting the driver handle the underlying physical connections. It shows how to get the underlying connections from the framework so you can set the necessary parameter.

1. Add the oracle.jdbc.useTrueCacheDriverConnection=true connection property to the connection URL in the persistence.xml file.

2. In the methods that need to use a True Cache connection, unwrap the session, use the doWork method to retrieve the underlying JDBC connection, and set the necessary read-only parameter for the connection. For example:

   Session session = em.unwrap(Session.class);
   session.doWork(new Work() {
   
      @Override
      public void execute(Connection con) throws SQLException {
         // if it is connected to primary, I want the connection to switch to true_cache now
         if(!con.isReadOnly()) {
            // The below code demonstrates the connection is to primary now        
            System.out.println("Query getting executed on:");
            Statement statement = con.createStatement();
            ResultSet rs = statement.executeQuery("SELECT database_role from v$database");
            rs.next();        
            System.out.println("Database role : " + rs.getString(1));    
            rs.close();
   
            // Now switching the connections to true cache
            con.setReadOnly(true);
            // The below code demonstrates the connection is to true cache now        
            System.out.println("After set read only true, Query getting executed on:");
            Statement statement2 = con.createStatement();
            ResultSet rs2 = null;
   
            rs2 = statement2.executeQuery("SELECT database_role from v$database");
            rs2.next();        
            System.out.println("Database role : " + rs2.getString(1));        
            rs2.close()
         }
      }
   });