仿照JBOSS实现PreparedStatementCache

git-svn-id: http://code.alibabatech.com/svn/druid/trunk@912 b9813039-fb51-4c41-a8b9-e21c2acb5095

src/main/java/com/alibaba/druid/pool/ConnectionHolder.java

@@ -67,11 +67,11 @@ public final class ConnectionHolder {
         this.lastActiveTimeMillis = lastActiveMillis;
     }
 
-    public void addTrace(Statement stmt) {
+    public void addTrace(PoolableStatement stmt) {
         statementTrace.add(stmt);
     }
 
-    public void removeTrace(Statement stmt) {
+    public void removeTrace(PoolableStatement stmt) {
         statementTrace.remove(stmt);
     }