/*
* 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.statement;
import java.lang.reflect.Array;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.List;
import java.util.Map;
import net.paoding.rose.jade.annotation.SQLType;
import net.paoding.rose.jade.dataaccess.DataAccess;
import net.paoding.rose.jade.dataaccess.DataAccessFactory;
import org.springframework.dao.EmptyResultDataAccessException;
import org.springframework.dao.IncorrectResultSizeDataAccessException;
import org.springframework.jdbc.core.RowMapper;
/**
* 实现 SELECT 查询。
*
* @author 王志亮 [qieqie.wang@gmail.com]
* @author 廖涵 [in355hz@gmail.com]
*/
public class SelectQuerier implements Querier {
private final RowMapper rowMapper;
private final Class<?> returnType;
private final DataAccessFactory dataAccessProvider;
public SelectQuerier(DataAccessFactory dataAccessProvider, StatementMetaData metaData,
RowMapper rowMapper) {
this.dataAccessProvider = dataAccessProvider;
this.returnType = metaData.getMethod().getReturnType();
this.rowMapper = rowMapper;
}
@Override
public Object execute(SQLType sqlType, StatementRuntime... runtimes) {
return execute(sqlType, (StatementRuntime) runtimes[0]);
}
public Object execute(SQLType sqlType, StatementRuntime runtime) {
DataAccess dataAccess = dataAccessProvider.getDataAccess(//
runtime.getMetaData(), runtime.getProperties());
// 执行查询
List<?> listResult = dataAccess.select(runtime.getSQL(), runtime.getArgs(), rowMapper);
final int sizeResult = listResult.size();
// 将 Result 转成方法的返回类型
if (returnType.isAssignableFrom(List.class)) {
// 返回 List 集合
return listResult;
} else if (returnType.isArray() && byte[].class != returnType) {
Object array = Array.newInstance(returnType.getComponentType(), sizeResult);
if (returnType.getComponentType().isPrimitive()) {
int len = listResult.size();
for (int i = 0; i < len; i++) {
Array.set(array, i, listResult.get(i));
}
} else {
listResult.toArray((Object[]) array);
}
return array;
} else if (Map.class.isAssignableFrom(returnType)) {
// 将返回的 KeyValuePair 转换成 Map 对象
// 因为entry.key可能为null，所以使用HashMap
Map<Object, Object> map;
if (returnType.isAssignableFrom(HashMap.class)) {
map = new HashMap<Object, Object>(listResult.size() * 2);
} else if (returnType.isAssignableFrom(Hashtable.class)) {
map = new Hashtable<Object, Object>(listResult.size() * 2);
} else {
throw new Error(returnType.toString());
}
for (Object obj : listResult) {
if (obj == null) {
continue;
}
Map.Entry<?, ?> entry = (Map.Entry<?, ?>) obj;
if (map.getClass() == Hashtable.class && entry.getKey() == null) {
continue;
}
map.put(entry.getKey(), entry.getValue());
}
return map;
} else if (returnType.isAssignableFrom(HashSet.class)) {
// 返回 Set 集合
return new HashSet<Object>(listResult);
} else {
if (sizeResult == 1) {
// 返回单个 Bean、Boolean等类型对象
return listResult.get(0);
} else if (sizeResult == 0) {
// 基础类型的抛异常，其他的返回null
if (returnType.isPrimitive()) {
String msg = "Incorrect result size: expected 1, actual " + sizeResult + ": "
+ runtime.getMetaData();
throw new EmptyResultDataAccessException(msg, 1);
} else {
return null;
}
} else {
// IncorrectResultSizeDataAccessException
String msg = "Incorrect result size: expected 0 or 1, actual " + sizeResult + ": "
+ runtime.getMetaData();
throw new IncorrectResultSizeDataAccessException(msg, 1, sizeResult);
}
}
}
}