/*
* 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.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import net.paoding.rose.jade.annotation.KeyColumnOfMap;
import net.paoding.rose.jade.statement.StatementMetaData;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.dao.TypeMismatchDataAccessException;
import org.springframework.jdbc.IncorrectResultSetColumnCountException;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.support.JdbcUtils;
/**
* 在将SQL结果集某一行的两列，一列作为key，一列作为value，形成一个key-value映射对。
*
* @author 王志亮 [qieqie.wang@gmail.com]
* @author 廖涵 [in355hz@gmail.com]
*
*/
public class MapEntryColumnRowMapper implements RowMapper {
private static Log logger = LogFactory.getLog(MapEntryColumnRowMapper.class);
private String keyColumn;
private int keyColumnIndex = 1;
private int valueColumnIndex = 2;
private Class<?> keyType, valueType;
private StatementMetaData modifier;
public MapEntryColumnRowMapper(StatementMetaData modifier, Class<?> requiredType) {
this.modifier = modifier;
Class<?>[] genericTypes = modifier.getGenericReturnTypes();
if (genericTypes.length < 2) {
throw new IllegalArgumentException("please set map generic parameters in method: "
+ modifier.getMethod());
}
// 获取 Key 类型与列
KeyColumnOfMap mapKey = modifier.getAnnotation(KeyColumnOfMap.class);
// 设置 Key 类型与列
this.keyColumn = (mapKey != null) ? mapKey.value() : null;
this.keyType = genericTypes[0];
this.valueType = genericTypes[1];
}
public Object mapRow(ResultSet rs, int rowNum) throws SQLException {
// 验证列的数目
if (rowNum == 0) {
ResultSetMetaData rsmd = rs.getMetaData();
int nrOfColumns = rsmd.getColumnCount();
if (nrOfColumns != 2) {
throw new IncorrectResultSetColumnCountException(2, nrOfColumns);
}
if (StringUtils.isNotEmpty(keyColumn)) {
keyColumnIndex = rs.findColumn(keyColumn);
if (keyColumnIndex == 1) {
valueColumnIndex = 2;
} else if (keyColumnIndex == 2) {
valueColumnIndex = 1;
} else {
throw new IllegalArgumentException(String.format(
"wrong key name %s for method: %s ", keyColumn, modifier.getMethod()));
}
keyColumn = null;
}
if (logger.isDebugEnabled()) {
logger.debug(String.format("keyIndex=%s; valueIndex=%s; for method: %s ",
keyColumnIndex, valueColumnIndex, modifier.getMethod()));
}
}
// 从 JDBC ResultSet 获取 Key
Object key = JdbcUtils.getResultSetValue(rs, keyColumnIndex, keyType);
if (key != null && !keyType.isInstance(key)) {
ResultSetMetaData rsmd = rs.getMetaData();
throw new TypeMismatchDataAccessException( // NL
"Type mismatch affecting row number " + rowNum + " and column type '"
+ rsmd.getColumnTypeName(keyColumnIndex) + "' expected type is '"
+ keyType + "'");
}
// 从 JDBC ResultSet 获取 Value
Object value = JdbcUtils.getResultSetValue(rs, valueColumnIndex, valueType);
if (value != null && !valueType.isInstance(value)) {
ResultSetMetaData rsmd = rs.getMetaData();
throw new TypeMismatchDataAccessException( // NL
"Type mismatch affecting row number " + rowNum + " and column type '"
+ rsmd.getColumnTypeName(valueColumnIndex) + "' expected type is '"
+ valueType + "'");
}
// key有可能为null，不过我们还是做进去
return new MapEntryImpl<Object, Object>(key, value);
}
}