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/*
 * $Header: /home/cvs/jakarta-commons/dbutils/src/java/org/apache/commons/dbutils/BasicRowProcessor.java,v 1.5 2003/11/11 00:53:19 dgraham Exp $
 * $Revision: 1.5 $
 * $Date: 2003/11/11 00:53:19 $
 * 
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 *
 */

package org.apache.commons.dbutils;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * Basic implementation of the RowProcessor interface.
 * This class is a thread-safe Singleton.
 * 
 * @see RowProcessor
 * 
 * @author Henri Yandell
 * @author Juozas Baliuka
 * @author David Graham
 * @author Yoav Shapira
 */
public class BasicRowProcessor implements RowProcessor {

    /**
     * Set a bean's primitive properties to these defaults when SQL NULL 
     * is returned.  These are the same as the defaults that ResultSet get* 
     * methods return in the event of a NULL column.
     */
    private static final Map primitiveDefaults = new HashMap();

    static {
        primitiveDefaults.put(Integer.TYPE, new Integer(0));
        primitiveDefaults.put(Short.TYPE, new Short((short) 0));
        primitiveDefaults.put(Byte.TYPE, new Byte((byte) 0));
        primitiveDefaults.put(Float.TYPE, new Float(0));
        primitiveDefaults.put(Double.TYPE, new Double(0));
        primitiveDefaults.put(Long.TYPE, new Long(0));
        primitiveDefaults.put(Boolean.TYPE, Boolean.FALSE);
        primitiveDefaults.put(Character.TYPE, new Character('\u0000'));
    }

    /**
     * Special array index that indicates there is no bean property that
     * matches a column from a ResultSet.
     */
    private static final int PROPERTY_NOT_FOUND = -1;

    /**
     * The Singleton instance of this class.
     */
    private static final BasicRowProcessor instance = new BasicRowProcessor();

    /**
     * Returns the Singleton instance of this class.
     *
     * @return The single instance of this class.
     */
    public static BasicRowProcessor instance() {
        return instance;
    }

    /**
     * Protected constructor for BasicRowProcessor subclasses only.
     */
    protected BasicRowProcessor() {
        super();
    }

    /**
     * Convert a ResultSet row into an Object[].
     * This implementation copies column values into the array in the same 
     * order they're returned from the ResultSet.  Array elements
     * will be set to null if the column was SQL NULL.
     *
     * @see org.apache.commons.dbutils.RowProcessor#toArray(java.sql.ResultSet)
     */
    public Object[] toArray(ResultSet rs) throws SQLException {
        ResultSetMetaData meta = rs.getMetaData();
        int cols = meta.getColumnCount();
        Object[] result = new Object[cols];

        for (int i = 0; i < cols; i++) {
            result[i] = rs.getObject(i + 1);
        }

        return result;
    }

    /**
     * Convert a ResultSet row into a JavaBean.  This 
     * implementation uses reflection and BeanInfo classes to 
     * match column names to bean property names.  Properties are matched to 
     * columns based on several factors:
     * 
*
    *
  1. * The class has a writable property with the same name as a column. * The name comparison is case insensitive. *
  2. * *
  3. * The property's set method parameter type matches the column * type. If the data types do not match, the setter will not be called. *
  4. *
* *

* Primitive bean properties are set to their defaults when SQL NULL is * returned from the ResultSet. Numeric fields are set to 0 * and booleans are set to false. Object bean properties are set to * null when SQL NULL is returned. This is the same behavior * as the ResultSet get* methods. *

* * @see org.apache.commons.dbutils.RowProcessor#toBean(java.sql.ResultSet, java.lang.Class) */ public Object toBean(ResultSet rs, Class type) throws SQLException { PropertyDescriptor[] props = this.propertyDescriptors(type); ResultSetMetaData rsmd = rs.getMetaData(); int[] columnToProperty = this.mapColumnsToProperties(rsmd, props); int cols = rsmd.getColumnCount(); return this.createBean(rs, type, props, columnToProperty, cols); } /** * Convert a ResultSet into a List of JavaBeans. * This implementation uses reflection and BeanInfo classes to * match column names to bean property names. Properties are matched to * columns based on several factors: *
*
    *
  1. * The class has a writable property with the same name as a column. * The name comparison is case insensitive. *
  2. * *
  3. * The property's set method parameter type matches the column * type. If the data types do not match, the setter will not be called. *
  4. *
* *

* Primitive bean properties are set to their defaults when SQL NULL is * returned from the ResultSet. Numeric fields are set to 0 * and booleans are set to false. Object bean properties are set to * null when SQL NULL is returned. This is the same behavior * as the ResultSet get* methods. *

* * @see org.apache.commons.dbutils.RowProcessor#toBeanList(java.sql.ResultSet, java.lang.Class) */ public List toBeanList(ResultSet rs, Class type) throws SQLException { List results = new ArrayList(); if (!rs.next()) { return results; } PropertyDescriptor[] props = this.propertyDescriptors(type); ResultSetMetaData rsmd = rs.getMetaData(); int[] columnToProperty = this.mapColumnsToProperties(rsmd, props); int cols = rsmd.getColumnCount(); do { results.add(this.createBean(rs, type, props, columnToProperty, cols)); } while (rs.next()); return results; } /** * Creates a new object and initializes its fields from the ResultSet. * * @param rs The result set * @param type The bean type (the return type of the object) * @param props The property descriptors * @param columnToProperty The column indices in the result set * @param cols The number of columns * @return An initialized object. * @throws SQLException If a database error occurs */ private Object createBean( ResultSet rs, Class type, PropertyDescriptor[] props, int[] columnToProperty, int cols) throws SQLException { Object bean = this.newInstance(type); for (int i = 1; i <= cols; i++) { if (columnToProperty[i] == PROPERTY_NOT_FOUND) { continue; } Object value = rs.getObject(i); PropertyDescriptor prop = props[columnToProperty[i]]; Class propType = prop.getPropertyType(); if (propType != null && value == null && propType.isPrimitive()) { value = primitiveDefaults.get(propType); } this.callSetter(bean, prop, value); } return bean; } /** * The positions in the returned array represent column numbers. The values * stored at each position represent the index in the PropertyDescriptor[] * for the bean property that matches the column name. If no bean property * was found for a column, the position is set to PROPERTY_NOT_FOUND. * * @param rsmd The result set meta data containing column information * @param props The bean property descriptors * @return An int[] with column index to property index mappings. The 0th * element is meaningless as column indexing starts at 1. * * @throws SQLException If a database error occurs */ private int[] mapColumnsToProperties( ResultSetMetaData rsmd, PropertyDescriptor[] props) throws SQLException { int cols = rsmd.getColumnCount(); int columnToProperty[] = new int[cols + 1]; for (int col = 1; col <= cols; col++) { String columnName = rsmd.getColumnName(col); for (int i = 0; i < props.length; i++) { if (columnName.equalsIgnoreCase(props[i].getName())) { columnToProperty[col] = i; break; } else { columnToProperty[col] = PROPERTY_NOT_FOUND; } } } return columnToProperty; } /** * Convert a ResultSet row into a Map. This * implementation returns a Map with case insensitive column * names as keys. Calls to map.get("COL") and * map.get("col") return the same value. * @see org.apache.commons.dbutils.RowProcessor#toMap(java.sql.ResultSet) */ public Map toMap(ResultSet rs) throws SQLException { Map result = new CaseInsensitiveHashMap(); ResultSetMetaData rsmd = rs.getMetaData(); int cols = rsmd.getColumnCount(); for (int i = 1; i <= cols; i++) { result.put(rsmd.getColumnName(i), rs.getObject(i)); } return result; } /** * Calls the setter method on the target object for the given property. * If no setter method exists for the property, this method does nothing. * @param target The object to set the property on. * @param prop The property to set. * @param value The value to pass into the setter. * @throws SQLException if an error occurs setting the property. */ private void callSetter( Object target, PropertyDescriptor prop, Object value) throws SQLException { Method setter = prop.getWriteMethod(); if (setter == null) { return; } Class[] params = setter.getParameterTypes(); try { // Don't call setter if the value object isn't the right type if (this.isCompatibleType(value, params[0])) { setter.invoke(target, new Object[] { value }); } } catch (IllegalArgumentException e) { throw new SQLException( "Cannot set " + prop.getName() + ": " + e.getMessage()); } catch (IllegalAccessException e) { throw new SQLException( "Cannot set " + prop.getName() + ": " + e.getMessage()); } catch (InvocationTargetException e) { throw new SQLException( "Cannot set " + prop.getName() + ": " + e.getMessage()); } } /** * ResultSet.getObject() returns an Integer object for an INT column. The * setter method for the property might take an Integer or a primitive int. * This method returns true if the value can be successfully passed into * the setter method. Remember, Method.invoke() handles the unwrapping * of Integer into an int. * * @param value The value to be passed into the setter method. * @param type The setter's parameter type. * @return boolean True if the value is compatible. */ private boolean isCompatibleType(Object value, Class type) { // Do object check first, then primitives if (value == null || type.isInstance(value)) { return true; } else if ( type.equals(Integer.TYPE) && Integer.class.isInstance(value)) { return true; } else if (type.equals(Long.TYPE) && Long.class.isInstance(value)) { return true; } else if ( type.equals(Double.TYPE) && Double.class.isInstance(value)) { return true; } else if (type.equals(Float.TYPE) && Float.class.isInstance(value)) { return true; } else if (type.equals(Short.TYPE) && Short.class.isInstance(value)) { return true; } else if (type.equals(Byte.TYPE) && Byte.class.isInstance(value)) { return true; } else if ( type.equals(Character.TYPE) && Character.class.isInstance(value)) { return true; } else if ( type.equals(Boolean.TYPE) && Boolean.class.isInstance(value)) { return true; } else { return false; } } /** * Returns a new instance of the given Class. * * @param c The Class to create an object from. * @return A newly created object of the Class. * @throws SQLException if creation failed. */ private Object newInstance(Class c) throws SQLException { try { return c.newInstance(); } catch (InstantiationException e) { throw new SQLException( "Cannot create " + c.getName() + ": " + e.getMessage()); } catch (IllegalAccessException e) { throw new SQLException( "Cannot create " + c.getName() + ": " + e.getMessage()); } } /** * Returns a PropertyDescriptor[] for the given Class. * * @param c The Class to retrieve PropertyDescriptors for. * @return A PropertyDescriptor[] describing the Class. * @throws SQLException if introspection failed. */ private PropertyDescriptor[] propertyDescriptors(Class c) throws SQLException { // Introspector caches BeanInfo classes for better performance BeanInfo beanInfo = null; try { beanInfo = Introspector.getBeanInfo(c); } catch (IntrospectionException e) { throw new SQLException( "Bean introspection failed: " + e.getMessage()); } return beanInfo.getPropertyDescriptors(); } /** * A Map that converts all keys to lowercase Strings for case insensitive * lookups. This is needed for the toMap() implementation because * databases don't consistenly handle the casing of column names. */ private static class CaseInsensitiveHashMap extends HashMap { /** * @see java.util.Map#containsKey(java.lang.Object) */ public boolean containsKey(Object key) { return super.containsKey(key.toString().toLowerCase()); } /** * @see java.util.Map#get(java.lang.Object) */ public Object get(Object key) { return super.get(key.toString().toLowerCase()); } /** * @see java.util.Map#put(java.lang.Object, java.lang.Object) */ public Object put(Object key, Object value) { return super.put(key.toString().toLowerCase(), value); } /** * @see java.util.Map#putAll(java.util.Map) */ public void putAll(Map m) { Iterator iter = m.keySet().iterator(); while (iter.hasNext()) { Object key = iter.next(); Object value = m.get(key); this.put(key, value); } } /** * @see java.util.Map#remove(java.lang.ObjecT) */ public Object remove(Object key) { return super.remove(key.toString().toLowerCase()); } } }
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