This patch is taken from gentoo (https://gitweb.gentoo.org/repo/gentoo.git/tree/dev-java/avalon-logkit/files/avalon-logkit-2.1-java7.patch).

It adds missing implementations of abstract methods.

diff -Nur avalon-logkit-2.1/src/java/org/apache/log/output/db/DefaultDataSource.java avalon-logkit-2.1_patched//src/java/org/apache/log/output/db/DefaultDataSource.java
--- avalon-logkit-2.1/src/java/org/apache/log/output/db/DefaultDataSource.java	2005-08-30 05:03:49.000000000 +0300
+++ avalon-logkit-2.1_patched//src/java/org/apache/log/output/db/DefaultDataSource.java	2011-09-27 08:27:49.313005212 +0300
@@ -20,7 +20,9 @@
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
+import java.sql.SQLFeatureNotSupportedException;
 import javax.sql.DataSource;
+import java.util.logging.Logger;
 
 /**
  * A basic datasource that doesn't do any pooling but just wraps
@@ -111,4 +113,16 @@
     {
         m_logWriter = logWriter;
     }
+
+    public boolean isWrapperFor(Class cls) {
+        return false;
+    }
+ 
+    public Object unwrap(Class cls) throws SQLException {
+        throw new SQLException("Not a wrapper for " + cls);
+    }
+    
+    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
+        throw new SQLFeatureNotSupportedException("Not a supported feature");
+    }
 }