/*
* Copyright 2009-2010 the original author or authors.
*
* 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 i 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 net.paoding.rose.jade.rowmapper;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import net.paoding.rose.jade.annotation.RowHandler;
import net.paoding.rose.jade.statement.StatementMetaData;
import org.apache.commons.lang.ClassUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanInstantiationException;
import org.springframework.jdbc.core.ColumnMapRowMapper;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.SingleColumnRowMapper;
/**
* 支持DAO方法返回类型：
* <p>
* <ul>
* <li>int、long等primitive：期望返回单列、1行</li>
* <li>Integer、Long等包装类型的：期望返回单列、0行或1行</li>
* <li>String、BigDecimal：期望返回单列，0行或1行</li>
* <li>java.util.Date及其子类：期望返回单列，0行或1行</li>
* <li>byte[]：期望返回单行、单列；列类型可转化为byte[]类型(比如blob类型)</li>
* <li>Blob、Clob：期望返回单，0行或1行</li>
* <li><code>数组(int[]、String[]等)：期望返回单列，多行；</li>
* <li>数组(User[]等)：期望返回多列，多行；</li>
* <li>集合(List<Integer>、Set<String>等): 期望返回单列，多行；</li>
* <li>集合(List<User>、Set<User>等): 期望返回单列，多行；</li>
* <li>映射(Map<String, Date>): 期望返回2列，多行</li>
* <li>映射(Map<String, User>): 期望返回多列，多行</li>
* <li>映射(Map<String, String[]>): 期望返回多列，多行</li>
* <ul>
*
* @author 王志亮 [qieqie.wang@gmail.com]
* @author 廖涵 [in355hz@gmail.com]
*/
public class DefaultRowMapperFactory implements RowMapperFactory {
private static Log logger = LogFactory.getLog(RowMapperFactory.class);
private Map<String, RowMapper> rowMappers = new HashMap<String, RowMapper>();
@Override
public RowMapper getRowMapper(StatementMetaData modifier) {
RowHandler rowHandler = modifier.getAnnotation(RowHandler.class);
if (rowHandler != null) {
if (rowHandler.rowMapper() != RowHandler.ByDefault.class) {
try {
RowMapper rowMapper = rowHandler.rowMapper().newInstance();
if (logger.isInfoEnabled()) {
logger.info("using rowMapper " + rowMapper + " for " + modifier);
}
return rowMapper;
} catch (Exception ex) {
throw new BeanInstantiationException(rowHandler.rowMapper(), ex.getMessage(),
ex);
}
}
}
//
Class<?> returnClassType = modifier.getMethod().getReturnType();
Class<?> rowType = getRowType(modifier);
// BUGFIX: SingleColumnRowMapper 处理 Primitive Type 抛异常
if (rowType.isPrimitive()) {
rowType = ClassUtils.primitiveToWrapper(rowType);
}
// 根据类型创建 RowMapper
RowMapper rowMapper;
// 返回单列的查询的(或者返回只有2列的Map类型查询的)
if (TypeUtils.isColumnType(rowType)) {
if (returnClassType == Map.class) {
rowMapper = new MapEntryColumnRowMapper(modifier, rowType);
} else {
rowMapper = new SingleColumnRowMapper(rowType);
}
}
// 返回多列的，用Bean对象、集合、映射、数组来表示每一行的
else {
if (rowType == Map.class) {
rowMapper = new ColumnMapRowMapper();
} else if (rowType.isArray()) {
rowMapper = new ArrayRowMapper(rowType);
} else if ((rowType == List.class) || (rowType == Collection.class)) {
rowMapper = new ListRowMapper(modifier);
} else if (rowType == Set.class) {
rowMapper = new SetRowMapper(modifier);
} else {
boolean checkColumns = (rowHandler == null) ? true : rowHandler.checkColumns();
boolean checkProperties = (rowHandler == null) ? false : rowHandler
.checkProperties();
String key = rowType.getName() + "[checkColumns=" + checkColumns
+ "&checkProperties=" + checkProperties + "]";
rowMapper = rowMappers.get(key);
if (rowMapper == null) {
rowMapper = new BeanPropertyRowMapper(rowType, checkColumns, checkProperties); // jade's BeanPropertyRowMapper here
rowMappers.put(key, rowMapper);
}
}
// 如果DAO方法最终返回的是Map，rowMapper要返回Map.Entry对象
if (returnClassType == Map.class) {
rowMapper = new MapEntryRowMapper(modifier, rowMapper);
}
}
if (logger.isInfoEnabled()) {
logger.info("using rowMapper " + rowMapper + " for " + modifier);
}
return rowMapper;
}
// 获得返回的集合元素类型
private static Class<?> getRowType(StatementMetaData statementMetaData) {
Class<?> returnClassType = statementMetaData.getMethod().getReturnType();
if (Collection.class.isAssignableFrom(returnClassType)) {
return getRowTypeFromCollectionType(statementMetaData, returnClassType);
} else if (Map.class == returnClassType) {
return getRowTypeFromMapType(statementMetaData, returnClassType);
} else if (returnClassType.isArray() && returnClassType != byte[].class) {
// 数组类型, 支持多重数组
return returnClassType.getComponentType();
}
// 此时代表整个DAO方法只关心结果集第一行
return returnClassType;
}
private static Class<?> getRowTypeFromMapType(StatementMetaData modifier,
Class<?> returnClassType) {
Class<?> rowType;
// 获取 Map<K, V> 值元素类型
Class<?>[] genericTypes = modifier.getGenericReturnTypes();
if (genericTypes.length != 2) {
throw new IllegalArgumentException("the returned generic type '"
+ returnClassType.getName() + "' should has two actual type parameters.");
}
rowType = genericTypes[1]; // 取 V 类型
return rowType;
}
private static Class<?> getRowTypeFromCollectionType(StatementMetaData modifier,
Class<?> returnClassType) {
Class<?> rowType;
// 仅支持 List / Collection / Set
if ((returnClassType != List.class) && (returnClassType != Collection.class)
&& (returnClassType != Set.class)) {
throw new IllegalArgumentException("error collection type " + returnClassType.getName()
+ "; only support List, Set, Collection");
}
// 获取集合元素类型
Class<?>[] genericTypes = modifier.getGenericReturnTypes();
if (genericTypes.length != 1) {
throw new IllegalArgumentException("the returned generic type '"
+ returnClassType.getName() + "' should has a actual type parameter.");
}
rowType = genericTypes[0];
return rowType;
}
}