[dbutils] ResultSetRowProcessor abstract handler and some classes rework

• Key: DBUTILS-16
• Type: Improvement
• Status: Closed
• Resolution: Fixed
• Priority: Minor
• Assignee: Unassigned
• Reporter: Mikhail Krivoshein
• Fix Version/s: 1.1

Environment

Operating System: All
Platform: All

Description

Index: ArrayListHandler.java
===================================================================
RCS file: /home/cvspublic/jakarta-
commons/dbutils/src/java/org/apache/commons/dbutils/handlers/ArrayListHandler.ja
va,v
retrieving revision 1.4
diff -u -r1.4 ArrayListHandler.java
— ArrayListHandler.java 28 Feb 2004 00:12:22 -0000 1.4
+++ ArrayListHandler.java 4 Jun 2004 13:24:00 -0000
@@ -1,82 +1,68 @@
/*

• Copyright 2003-2004 The Apache Software Foundation

• *
• * Licensed under the Apache License, Version 2.0 (the "License");
• * you may not use this file except in compliance with the License.
• * You may obtain a copy of the License at
• *
• * http://www.apache.org/licenses/LICENSE-2.0
• *
  + *
  + * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  + * use this file except in compliance with the License. You may obtain a copy
  + * of the License at
  + *
  + * http://www.apache.org/licenses/LICENSE-2.0
  + *

• Unless required by applicable law or agreed to in writing, software

• * distributed under the License is distributed on an "AS IS" BASIS,
• * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
• * See the License for the specific language governing permissions and
• * limitations under the License.
  + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  + * License for the specific language governing permissions and limitations
  + * under the License.
  */
  package org.apache.commons.dbutils.handlers;

import java.sql.ResultSet;
import java.sql.SQLException;
-import java.util.ArrayList;
-import java.util.List;

-import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.RowProcessor;

/**

• * <code>ResultSetHandler</code> implementation that converts the
• * <code>ResultSet</code> into a <code>List</code> of <code>Object[]</code>s.
• * This class is thread safe.
  + * <code>ResultSetHandler</code> implementation that converts the
  <code>ResultSet</code>
  + * into a <code>List</code> of <code>Object[]</code>s. This class is
  + * thread safe.

• @see ResultSetHandler
  */
  -public class ArrayListHandler implements ResultSetHandler {
  -

• /**
• * The RowProcessor implementation to use when converting rows
• * into Object[]s.
• */
• private RowProcessor convert = ArrayHandler.ROW_PROCESSOR;
  -
• /**
• * Creates a new instance of ArrayListHandler using a
• * <code>BasicRowProcessor</code> for conversions.
• */
• public ArrayListHandler() { - super(); - }
  -
  - /**
  - * Creates a new instance of ArrayListHandler.
  - *
  - * @param convert The <code>RowProcessor</code> implementation
  - * to use when converting rows into Object[]s.
  - */
  - public ArrayListHandler(RowProcessor convert) { - super(); - this.convert = convert; - }
  -
  - /**
  - * Convert each row's columns into an <code>Object[]</code> and store them
  - * in a <code>List</code> in the same order they are returned from the
  - * <code>ResultSet.next()</code> method.
  - *
  - * @return A <code>List</code> of <code>Object[]</code>s, never
  - * <code>null</code>.
  - *
  - * @throws SQLException
  - * @see org.apache.commons.dbutils.ResultSetHandler#handle
  (java.sql.ResultSet)
  - */
  - public Object handle(ResultSet rs) throws SQLException {
  -
  - List result = new ArrayList();
  -
  - while (rs.next()) { - result.add(this.convert.toArray(rs)); - }
  -
  - return result;
  - }
  +public class ArrayListHandler extends ResultSetRowProcessor {
  
  + /**
  + * The RowProcessor implementation to use when converting rows into
  + * Object[]s.
  + */
  + private RowProcessor convert = ArrayHandler.ROW_PROCESSOR;
  +
  + /**
  + * Creates a new instance of ArrayListHandler using a
  <code>BasicRowProcessor</code>
  + * for conversions.
  + */
  + public ArrayListHandler() { + super(); + }
  +
  + /**
  + * Creates a new instance of ArrayListHandler.
  + *
  + * @param convert The <code>RowProcessor</code> implementation to use
  when
  + * converting rows into Object[]s.
  + */
  + public ArrayListHandler(RowProcessor convert) { + super(); + this.convert = convert; + }
  +
  + /**
  + * Convert row's columns into an <code>Object[]</code>.
  + *
  + * @return <code>Object[]</code>, never <code>null</code>.
  + *
  + * @throws SQLException
  + * @see org.apache.commons.dbutils.handlers.ResultSetRowProcessor#handle
  (ResultSet)
  + */
  + protected Object handleRow(ResultSet rs) throws SQLException { + return this.convert.toArray(rs); + }
  }
  Index: ColumnListHandler.java
  ===================================================================
  RCS file: /home/cvspublic/jakarta-
  commons/dbutils/src/java/org/apache/commons/dbutils/handlers/ColumnListHandler.j
  ava,v
  retrieving revision 1.1
  diff -u -r1.1 ColumnListHandler.java
  — ColumnListHandler.java 9 Mar 2004 03:05:51 -0000 1.1
  +++ ColumnListHandler.java 4 Jun 2004 13:24:01 -0000
  @@ -1,100 +1,85 @@
  /*
  * Copyright 2004 The Apache Software Foundation
  - *
  - * Licensed under the Apache License, Version 2.0 (the "License");
  - * you may not use this file except in compliance with the License.
  - * You may obtain a copy of the License at
  - *
  - * http://www.apache.org/licenses/LICENSE-2.0
  - *
  + *
  + * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  + * use this file except in compliance with the License. You may obtain a copy
  + * of the License at
  + *
  + * http://www.apache.org/licenses/LICENSE-2.0
  + *
  * Unless required by applicable law or agreed to in writing, software
  - * distributed under the License is distributed on an "AS IS" BASIS,
  - * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  - * See the License for the specific language governing permissions and
  - * limitations under the License.
  + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  + * License for the specific language governing permissions and limitations
  + * under the License.
  */
  
  package org.apache.commons.dbutils.handlers;
  
  import java.sql.ResultSet;
  import java.sql.SQLException;
  -import java.util.ArrayList;
  -import java.util.List;
  -
  -import org.apache.commons.dbutils.ResultSetHandler;
  
  /**
  - * <code>ResultSetHandler</code> implementation that converts one
  - * <code>ResultSet</code> column into a <code>List</code> of
  - * <code>Object</code>s. This class is thread safe.
  + * <code>ResultSetHandler</code> implementation that converts one
  <code>ResultSet</code>
  + * column into a <code>List</code> of <code>Object</code>s. This class is
  + * thread safe.
  *
  * @see ResultSetHandler
  * @since DbUtils 1.1
  */
  -public class ColumnListHandler implements ResultSetHandler {
  +public class ColumnListHandler extends ResultSetRowProcessor {
  
  - /**
  - * The column number to retrieve.
  - */
  - private int columnIndex = 1;
  -
  - /**
  - * The column name to retrieve. Either columnName or columnIndex
  - * will be used but never both.
  - */
  - private String columnName = null;
  -
  - /**
  - * Creates a new instance of ColumnListHandler. The first column of each
  - * row will be returned from <code>handle()</code>.
  - */
  - public ColumnListHandler() {- super();- } }
  -
• /**
• * Creates a new instance of ColumnListHandler.
• *
• * @param columnIndex The index of the column to retrieve from the
• * <code>ResultSet</code>.
• */
• public ColumnListHandler(int columnIndex) { - this.columnIndex = columnIndex; - }
  -
• /**
• * Creates a new instance of ColumnListHandler.
• *
• * @param columnName The name of the column to retrieve from the
• * <code>ResultSet</code>.
• */
• public ColumnListHandler(String columnName) { - this.columnName = columnName; - }
  -
• /**
• * Returns one <code>ResultSet</code> column as a <code>List</code> of
• * <code>Object</code>s. The elements are added to the <code>List</code>
  via
• * the <code>ResultSet.getObject()</code> method.
• *
• * @return A <code>List</code> of <code>Object</code>s, never
• * <code>null</code>.
• *
• * @throws SQLException
• *
• * @see org.apache.commons.dbutils.ResultSetHandler#handle
  (java.sql.ResultSet)
• */
• public Object handle(ResultSet rs) throws SQLException {
  -
• List result = new ArrayList();
  -
• while (rs.next()) {
• if (this.columnName == null) { - result.add(rs.getObject(this.columnIndex)); - } else { - result.add(rs.getObject(this.columnName)); - }
• }
• return result;
• }
  + /**
  + * The column number to retrieve.
  + */
  + private int columnIndex = 1;
  +
  + /**
  + * The column name to retrieve. Either columnName or columnIndex will
  be used
  + * but never both.
  + */
  + private String columnName = null;
  +
  + /**
  + * Creates a new instance of ColumnListHandler. The first column of
  each row
  + * will be returned from <code>handle()</code>.
  + */
  + public ColumnListHandler() { + super(); + }
  +
  + /**
  + * Creates a new instance of ColumnListHandler.
  + *
  + * @param columnIndex The index of the column to retrieve from the
  <code>ResultSet</code>.
  + */
  + public ColumnListHandler(int columnIndex) { + this.columnIndex = columnIndex; + }
  +
  + /**
  + * Creates a new instance of ColumnListHandler.
  + *
  + * @param columnName The name of the column to retrieve from the
  <code>ResultSet</code>.
  + */
  + public ColumnListHandler(String columnName) { + this.columnName = columnName; + }
  +
  + /**
  + * Returns one <code>ResultSet</code> column value as
  <code>Object</code>.
  + *
  + * @return <code>Object</code>, never <code>null</code>.
  + *
  + * @throws SQLException
  + *
  + * @see org.apache.commons.dbutils.handlers.ResultSetRowProcessor#handle
  (ResultSet)
  + */
  + protected Object handleRow(ResultSet rs) throws SQLException
  Unknown macro: {+ if (this.columnName == null) { + return rs.getObject(this.columnIndex); + } else { + return rs.getObject(this.columnName); + }+ }
  
  }
  Index: MapListHandler.java
  ===================================================================
  RCS file: /home/cvspublic/jakarta-
  commons/dbutils/src/java/org/apache/commons/dbutils/handlers/MapListHandler.java
  ,v
  retrieving revision 1.4
  diff -u -r1.4 MapListHandler.java
  • • MapListHandler.java 28 Feb 2004 00:12:22 -0000 1.4
      +++ MapListHandler.java 4 Jun 2004 13:24:01 -0000
      @@ -17,10 +17,7 @@

import java.sql.ResultSet;
import java.sql.SQLException;
-import java.util.ArrayList;
-import java.util.List;

-import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.RowProcessor;

/**
@@ -30,7 +27,7 @@

• @see ResultSetHandler
  */
  -public class MapListHandler implements ResultSetHandler {
  +public class MapListHandler extends ResultSetRowProcessor { /** * The RowProcessor implementation to use when converting rows @@ -58,24 +55,16 @@ }

/**

• * Converts the <code>ResultSet</code> rows into a <code>List</code> of
• * <code>Map</code> objects.
  + * Converts the <code>ResultSet</code> row into a <code>Map</code> object.

• * @return A <code>List</code> of <code>Map</code>s, never null.
  + * @return A <code>Map</code>, never null.

• @throws SQLException

• * @see org.apache.commons.dbutils.ResultSetHandler#handle
  (java.sql.ResultSet)
  + * @see org.apache.commons.dbutils.handlers.ResultSetRowProcessor#handle
  (ResultSet)
  */
• public Object handle(ResultSet rs) throws SQLException {
  -
• List results = new ArrayList();
  -
• while (rs.next()) { - results.add(this.convert.toMap(rs)); - }
  -
• return results;
• }
  + protected Object handleRow(ResultSet rs) throws SQLException { + return this.convert.toMap(rs); + }

}
Index: src/java/org/apache/commons/dbutils/handlers/ResultSetRowProcessor.java
===================================================================
RCS file:
src/java/org/apache/commons/dbutils/handlers/ResultSetRowProcessor.java
diff -N src/java/org/apache/commons/dbutils/handlers/ResultSetRowProcessor.java
— /dev/null 1 Jan 1970 00:00:00 -0000
+++ src/java/org/apache/commons/dbutils/handlers/ResultSetRowProcessor.java
1 Jan 1970 00:00:00 -0000
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2003-2004 The Apache Software Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy
+ * of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.commons.dbutils.handlers;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.dbutils.ResultSetHandler;
+
+/**
+ * Abstract class that simplify development of <code>ResultSetHandler</code>
+ * classes that convert <code>ResultSet</code> into <code>List</code>.
+ */
+public abstract class ResultSetRowProcessor implements ResultSetHandler {
+ /**
+ * Whole <code>ResultSet</code> handler. It produce <code>List</code> as
+ * result. To convert individual rows into Java objects it uses
<code>handleRow(ResultSet)</code>
+ * method.
+ *
+ * @see #handleRow(ResultSet)
+ */
+ public Object handle(ResultSet rs) throws SQLException {
+ List rows = new ArrayList();
+ while (rs.next()) { + rows.add(this.handleRow(rs)); + }
+ return rows;
+ }
+
+ /**
+ * Row handler. Method converts current row into some Java object.
+ *
+ * @param rs <code>ResultSet</code> to process.
+ * @return row processing result
+ * @throws SQLException error occurs
+ */
+ protected abstract Object handleRow(ResultSet rs) throws SQLException;
+}

Comments

[David Graham]

I appreciate the patch but I won't apply anything that touches every line in a
file including the license. I will apply a patch that just touches the lines
necessary to make the change.

[Stefan Fleiter]

Created an attachment (id=13351)
Generic Implementaion of List creation and ResultSet traversal for *ListHandler.java

[Stefan Fleiter]

Same as above, but

• Other name
• implementation for BeanListHandler included
• BeanProcess.toBeanList and RowProcessor.toBeanList removed
• only those lines touched that haven been necessary for the change

Is this ok as it is or are further chnages needed?
Would (in another bug) a patch be accepted which would introduce a
dependency to commons-logging (see TODOs in ResultSetIterator.java)?

[Stefan Fleiter]

I think I need to rivise the patch more carefully.
The GenericListHandler class, f.e. should IMHO not have public visibility, it's
an implementation detail.

I will look at the patch once more and come back to you.

[David Graham]

DbUtils is intentionally a one jar distro and commons logging isn't really
needed. Those TODOs need to be removed. We should either swallow the exception
or throw it as some kind of RuntimeException.

[Stefan Fleiter]

I do not think that swallowing the exception would be a good decission, the user
(of DbUtils) should know something went wrong and we should not hide application
bugs and make debugging more difficult.

I just opened COM-1707 for this. Let's move the discussion there.

[Stefan Fleiter]

Created an attachment (id=13359)
New Patch, this time GenericListHandler has package visibility

[Stefan Fleiter]

I've just attached a new patch with the following diffrences to my last one:

• GenericListHandler has package visibility
• I think this class is an implementation detail. Maybe some day one would
  like to change the *ListHandler-classes to use composition to get the
  generic handle()-Method because one would like the classes to drive from
  some other class. If GenericListHandler has public visibility one has to
  support this class forever
• Fixed a typo.

The unittests all passed.
What do you think?

[Henri Yandell]

FIX or WONTFIX for 1.1.

[Henri Yandell]

Negative side of this is that it changes the public 1.0 API by removing toBeanList in a few places. So not usable for 1.1 in its entirety.

[Henri Yandell]

Version of the patch that does not remove the toBeanList methods.

I'm unsure if they should be deprecated - it feels that there is no reason to do so.

[Henri Yandell]

svn ci -m "Applying the code refactoring in #DBUTILS-16 - the new abstract class is currently not public. In a later release we can decide whe
ther to make it public or not (this is recorded in #DBUTILS-33"
Sending src/java/org/apache/commons/dbutils/handlers/ArrayListHandler.java
Sending src/java/org/apache/commons/dbutils/handlers/BeanListHandler.java
Sending src/java/org/apache/commons/dbutils/handlers/ColumnListHandler.java
Sending src/java/org/apache/commons/dbutils/handlers/MapListHandler.java
Transmitting file data ....
Committed revision 470975.

[Henri Yandell]

svn ci -m "Missed the new class from #DBUTILS-16. "
Adding src/java/org/apache/commons/dbutils/handlers/GenericListHandler.java
Transmitting file data .
Committed revision 470976.