From aee97922c4be64155f5fc1794d809bb73dbdd087 Mon Sep 17 00:00:00 2001
From: samskivert <samskivert@6335cc39-0255-0410-8fd6-9bcaacd3b74c>
Date: Fri, 4 Sep 2009 17:25:45 +0000
Subject: [PATCH] Extract the proxied Connection creation code into a JDBCUtil
 method.

git-svn-id: https://samskivert.googlecode.com/svn/trunk@2631 6335cc39-0255-0410-8fd6-9bcaacd3b74c
---
 .../samskivert/jdbc/AutoCloseOperation.java   | 25 +++------------
 src/java/com/samskivert/jdbc/JDBCUtil.java    | 32 +++++++++++++++++++
 2 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/src/java/com/samskivert/jdbc/AutoCloseOperation.java b/src/java/com/samskivert/jdbc/AutoCloseOperation.java
index 0d6f9d6d..22f1b75f 100644
--- a/src/java/com/samskivert/jdbc/AutoCloseOperation.java
+++ b/src/java/com/samskivert/jdbc/AutoCloseOperation.java
@@ -20,10 +20,6 @@
 
 package com.samskivert.jdbc;
 
-import java.lang.reflect.InvocationHandler;
-import java.lang.reflect.Method;
-import java.lang.reflect.Proxy;
-
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.sql.Statement;
@@ -52,24 +48,13 @@ public abstract class AutoCloseOperation<V>
     /**
      * Invokes {@link #cleanInvoke} and then closes any statements opened by that call.
      */
-    public final V invoke (final Connection conn, DatabaseLiaison liaison)
+    public final V invoke (Connection conn, DatabaseLiaison liaison)
         throws SQLException, PersistenceException
     {
-        // create a proxy to conn that collects any returned instances of Statement in stmts
-        final List<Statement> stmts = new ArrayList<Statement>(1);
-        Connection proxy = (Connection)Proxy.newProxyInstance(
-            Connection.class.getClassLoader(), PROXY_IFACES, new InvocationHandler() {
-            public Object invoke (Object proxy, Method method, Object[] args) throws Throwable {
-                Object result = method.invoke(conn, args);
-                if (result instanceof Statement) {
-                    stmts.add((Statement)result);
-                }
-                return result;
-            }
-        });
-
+        List<Statement> stmts = new ArrayList<Statement>(1);
+        conn = JDBCUtil.makeCollector(conn, stmts);
         try {
-            return cleanInvoke(proxy, liaison);
+            return cleanInvoke(conn, liaison);
         } finally {
             // if closing a statement throws an SQLException, we don't attempt to close the rest of
             // the statements -- an SQLException thrown on close is a problem with the underlying
@@ -80,6 +65,4 @@ public abstract class AutoCloseOperation<V>
             }
         }
     }
-
-    protected static Class<?>[] PROXY_IFACES = { Connection.class };
 }
diff --git a/src/java/com/samskivert/jdbc/JDBCUtil.java b/src/java/com/samskivert/jdbc/JDBCUtil.java
index 5fd43da7..f3a24192 100644
--- a/src/java/com/samskivert/jdbc/JDBCUtil.java
+++ b/src/java/com/samskivert/jdbc/JDBCUtil.java
@@ -21,8 +21,15 @@
 package com.samskivert.jdbc;
 
 import java.io.UnsupportedEncodingException;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Iterator;
+import java.util.List;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
@@ -31,6 +38,7 @@ import java.sql.Statement;
 
 import com.samskivert.io.PersistenceException;
 import com.samskivert.util.StringUtil;
+import com.samskivert.util.Tuple;
 
 import static com.samskivert.Log.log;
 
@@ -74,6 +82,27 @@ public class JDBCUtil
 	}
     }
 
+    /**
+     * Wraps the given connection in a proxied instance that will add all statements returned by
+     * methods called on the proxy (such as {@link Collection#createStatement}) to the supplied
+     * list. Thus you can create the proxy, pass the proxy to code that creates and uses statements
+     * and then close any statements created by the code that operated on that Connection before
+     * returning it to a pool, for example.
+     */
+    public static Connection makeCollector (final Connection conn, final List<Statement> stmts)
+    {
+        return (Connection)Proxy.newProxyInstance(
+            Connection.class.getClassLoader(), PROXY_IFACES, new InvocationHandler() {
+            public Object invoke (Object proxy, Method method, Object[] args) throws Throwable {
+                Object result = method.invoke(conn, args);
+                if (result instanceof Statement) {
+                    stmts.add((Statement)result);
+                }
+                return result;
+            }
+        });
+    }
+
     /**
      * Calls <code>stmt.executeUpdate()</code> on the supplied statement, checking to see that it
      * returns the expected update count and throwing a persistence exception if it does not.
@@ -621,4 +650,7 @@ public class JDBCUtil
         throw new SQLException("Table or Column not defined. [table=" + table +
                                ", col=" + column + "].");
     }
+
+    /** Used by {@link #makeCollectingConnection}. */
+    protected static Class<?>[] PROXY_IFACES = { Connection.class };
 }