/*
* 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.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.springframework.dao.EmptyResultDataAccessException;
import org.springframework.dao.IncorrectResultSizeDataAccessException;
import org.springframework.jdbc.core.RowMapper;
import net.paoding.rose.jade.annotation.SQLType;
import net.paoding.rose.jade.dataaccess.DataAccess;
import net.paoding.rose.jade.dataaccess.DataAccessFactory;
/**
* 实现 SELECT 查询。
*
* @author 王志亮 [qieqie.wang@gmail.com]
* @author 廖涵 [in355hz@gmail.com]
*/
@SuppressWarnings({"rawtypes", "unchecked"})
public class SelectQuerier implements Querier {
private final RowMapper rowMapper;
private final Class<?> returnType;
private final DataAccessFactory dataAccessFactory;
private final ResultConverter converter;
public SelectQuerier(DataAccessFactory dataAccessFactory, StatementMetaData metaData,
RowMapper rowMapper) {
this.dataAccessFactory = dataAccessFactory;
this.returnType = metaData.getReturnType();
this.rowMapper = rowMapper;
this.converter = makeResultConveter();
}
@Override
public Object execute(SQLType sqlType, StatementRuntime... runtimes) {
return execute(sqlType, (StatementRuntime) runtimes[0]);
}
public Object execute(SQLType sqlType, StatementRuntime runtime) {
DataAccess dataAccess = dataAccessFactory.getDataAccess(//
runtime.getMetaData(), runtime.getAttributes());
// 执行查询
List<?> listResult = dataAccess.select(runtime.getSQL(), runtime.getArgs(), rowMapper);
return converter.convert(runtime, listResult);
}
protected ResultConverter makeResultConveter() {
ResultConverter converter;
if (List.class == returnType || Collection.class == returnType || Iterable.class == returnType) {
converter = new ResultConverter() {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
return listResult;
}
};
}
else if (ArrayList.class == returnType) {
converter = new ResultConverter() {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
return new ArrayList(listResult);
}
};
}
else if (LinkedList.class == returnType) {
converter = new ResultConverter() {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
return new LinkedList(listResult);
}
};
}
else if (Set.class == returnType || HashSet.class == returnType) {
converter = new ResultConverter() {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
return new HashSet(listResult);
}
};
}
else if (Collection.class.isAssignableFrom(returnType)) {
converter = new ResultConverter() {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
Collection listToReturn;
try {
listToReturn = (Collection) returnType.newInstance();
} catch (Exception e) {
throw new Error("error to create instance of " + returnType.getName());
}
listToReturn.addAll(listResult);
return listToReturn;
}
};
}
else if (Iterator.class == returnType) {
converter = new ResultConverter() {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
return listResult.iterator();
}
};
}
else if (returnType.isArray() && byte[].class != returnType) {
if (returnType.getComponentType().isPrimitive()) {
converter = new ResultConverter() {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
Object array = Array.newInstance(returnType.getComponentType(), listResult.size());
int len = listResult.size();
for (int i = 0; i < len; i++) {
Array.set(array, i, listResult.get(i));
}
return array;
}
};
}
else {
converter = new ResultConverter() {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
Object array = Array.newInstance(returnType.getComponentType(), listResult.size());
return listResult.toArray((Object[]) array);
}
};
}
}
else if (Map.class == returnType || HashMap.class == returnType) {
converter = new MapConverter() {
@Override
protected Map creatMap(StatementRuntime runtime) {
return new HashMap();
}
};
}
else if (Hashtable.class == returnType) {
converter = new MapConverter() {
@Override
protected Map creatMap(StatementRuntime runtime) {
return new Hashtable();
}
};
}
else if (Map.class.isAssignableFrom(returnType)) {
converter = new MapConverter() {
@Override
protected Map creatMap(StatementRuntime runtime) {
try {
return (Map) returnType.newInstance();
} catch (Exception e) {
throw new Error("error to create instance of " + returnType.getName());
}
}
};
}
//
else {
converter = new ResultConverter() {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
final int sizeResult = listResult.size();
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);
}
}
};
}
return converter;
}
/**
* {@link ResultConverter} 负责将SELECT出来的List转化为DAO方法要求的返回结果
* <p>
*
*/
static interface ResultConverter {
Object convert(StatementRuntime runtime, List<?> listResult);
}
static abstract class MapConverter implements ResultConverter {
@Override
public Object convert(StatementRuntime runtime, List<?> listResult) {
Map map = creatMap(runtime);
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;
}
protected abstract Map creatMap(StatementRuntime runtime) ;
}
}