Extracting postgres connection object from tomcat connection pool and JPA - postgresql

Question

I have a Java EE app that runs in Tomcat, uses Tomcat connection pooling, over postgres database, and the application uses OpenJPA for ORM.
For some operations, I need to get access to LargeObjectManager API from postgres. That requires me having a reference to the actual postgres connection object.
So, I'm trying to drill into the connection object I get from OpenJPA, to get the actual Postgres one. But I'm stopped by a 'sun.misc.proxy.$ProxyNN' object, and I'm not sure how can I get further.
Here is what I'm doing now:
OpenJPAEntityManager oem = OpenJPAPersistence.cast(em);
// get open JPA connection object
Connection c = oem.getConnection();
// all the way down to what's no longer OpenJPA
c = ((DelegatingConnection)c).getInnermostDelegate()
And that's where I stop. The returned object is below. I can't call ProxyConnection methods on it, and I don't even know who creates these proxies (but I bet it's Tomcat DBCP).
c = {com.sun.proxy.$Proxy5#1793}"ProxyConnection[PooledConnection[Pooled connection wrapping physical connection org.postgresql.jdbc4.Jdbc4Connection#a7a434]]"
h = {org.apache.tomcat.jdbc.pool.ProxyConnection#5671}"ProxyConnection[PooledConnection[Pooled connection wrapping physical connection org.postgresql.jdbc4.Jdbc4Connection#a7a434]]"
connection = {org.apache.tomcat.jdbc.pool.PooledConnection#5673}"PooledConnection[Pooled connection wrapping physical connection org.postgresql.jdbc4.Jdbc4Connection#a7a434]"
poolProperties = {org.apache.tomcat.jdbc.pool.PoolProperties#5676}"ConnectionPool[defaultAutoCommit=false; defaultReadOnly=null; defaultTransactionIsolation=-1; defaultCatalog=null; driverClassName=null; maxActive=100; maxIdle=100; minIdle=10; initialSize=10; maxWait=30000; testOnBorrow=false; testOnReturn=false; timeBe...
connection = {com.sun.proxy.$Proxy0#5677}"Pooled connection wrapping physical connection org.postgresql.jdbc4.Jdbc4Connection#a7a434"
h = {org.postgresql.ds.jdbc23.AbstractJdbc23PooledConnection$ConnectionHandler#5686}
xaConnection = null
abandonTrace = null
timestamp = 1372621172141
lock = {java.util.concurrent.locks.ReentrantReadWriteLock#5678}"java.util.concurrent.locks.ReentrantReadWriteLock#9267fe[Write locks = 0, Read locks = 0]"
discarded = false
lastConnected = 1372620679402
lastValidated = 1372620679398
parent = {org.apache.tomcat.jdbc.pool.ConnectionPool#5674}
attributes = {java.util.HashMap#5679} size = 2
handler = {org.apache.tomcat.jdbc.pool.ProxyConnection#5671}"ProxyConnection[PooledConnection[Pooled connection wrapping physical connection org.postgresql.jdbc4.Jdbc4Connection#a7a434]]"
released = {java.util.concurrent.atomic.AtomicBoolean#5680}"false"
suspect = false
driver = null
pool = {org.apache.tomcat.jdbc.pool.ConnectionPool#5674}
properties = null
next = null
useEquals = true
tomcat: 7.0.22
postgres jdbc:9.2-1002
openJPA: 2.1.1

Answer 1

Give this a try, might require some tweaking but I believe it should work as is or at least give you some useful pointers of where are the proxies that need to be unwrapped
//unwrap proxy invocation handler
org.apache.tomcat.jdbc.pool.ProxyConnection tomcatProxy = (ProxyConnection) Proxy.getInvocationHandler(c);
org.apache.tomcat.jdbc.pool.PooledConnection tomcatPooledConnection = tomcatProxy.getConnection(); //if this doesn't work try getDelegateConnection!
Connection connection = tomcatPooledConnection.getConnection();
then try
org.postgresql.jdbc4.Jdbc4Connection jdbc4conn = (org.postgresql.jdbc4.Jdbc4Connection) connection;
jdbc4conn.getLargeObjectAPI();
if the above cast fails try:
org.postgresql.ds.jdbc23.AbstractJdbc23PooledConnection psAbstractPooledConn = Proxy.getInvocationHandler(connection.getProxy().getConnection());
Well, if it does not work, if you can give more info on these other objects and their attributes it will be really helpful, but the idea here is to get the invocation handlers generated using JDK Proxies and the connection from Tomcat proxies