Knut Anders Hatlen created DERBY-5872:
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Summary: Inconsistency between isWrapperFor() and unwrap() in
logical statements
Key: DERBY-5872
URL: https://issues.apache.org/jira/browse/DERBY-5872
Project: Derby
Issue Type: Bug
Components: JDBC
Affects Versions: 10.9.1.0, 10.8.1.2, 10.7.1.1, 10.6.1.0, 10.5.1.1, 10.4.1.3
Reporter: Knut Anders Hatlen
I noticed this when I refactored the logical statement classes in DERBY-5868.
The isWrapperFor() method forwards calls to the underlying physical statement,
but the unwrap() method works purely at the logical level.
For example, if you produce a LogicalPreparedStatement40 instance with this code
ClientConnectionPoolDataSource ds = new
ClientConnectionPoolDataSource();
ds.setDatabaseName("testdb");
ds.setCreateDatabase("create");
ds.setMaxStatements(10);
PooledConnection pc = ds.getPooledConnection();
Connection c = pc.getConnection();
PreparedStatement ps = c.prepareStatement("values 1");
you'll see that
System.out.println(ps.isWrapperFor(LogicalPreparedStatement40.class));
prints false, telling that ps is not a wrapper for LogicalPreparedStatement40.
However, trying to unwrap ps as a LogicalPreparedStatement succeeds:
LogicalPreparedStatement40 lps =
ps.unwrap(LogicalPreparedStatement40.class);
On the other hand
System.out.println(ps.isWrapperFor(PreparedStatement40.class));
prints true, indicating that ps is a wrapper for PreparedStatement40, but
trying to unwrap it as one, fails:
PreparedStatement40 ps4 = ps.unwrap(PreparedStatement40.class);
Exception in thread "main" java.sql.SQLException: Unable to unwrap for 'class
org.apache.derby.client.am.PreparedStatement40'
at
org.apache.derby.client.am.SQLExceptionFactory40.getSQLException(SQLExceptionFactory40.java:108)
at
org.apache.derby.client.am.SqlException.getSQLException(SqlException.java:364)
at
org.apache.derby.client.am.LogicalStatementEntity.unwrap(LogicalStatementEntity.java:258)
at
org.apache.derby.client.am.LogicalPreparedStatement.unwrap(LogicalPreparedStatement.java:57)
at Test.main(Test.java:37)
Caused by: org.apache.derby.client.am.SqlException: Unable to unwrap for 'class
org.apache.derby.client.am.PreparedStatement40'
... 3 more
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