/*
* Copyright 2009-2012 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 is 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 org.apache.ibatis.executor.keygen;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.TypeHandlerRegistry;
/**
* @author Clinton Begin
*/
/**
* JDBC3键值生成器,核心是使用JDBC3的Statement.getGeneratedKeys
*
*/
public class Jdbc3KeyGenerator implements KeyGenerator {
@Override
public void processBefore(Executor executor, MappedStatement ms, Statement stmt, Object parameter) {
// do nothing
}
@Override
public void processAfter(Executor executor, MappedStatement ms, Statement stmt, Object parameter) {
List<Object> parameters = new ArrayList<Object>();
parameters.add(parameter);
processBatch(ms, stmt, parameters);
}
//批处理
public void processBatch(MappedStatement ms, Statement stmt, List<Object> parameters) {
ResultSet rs = null;
try {
//核心是使用JDBC3的Statement.getGeneratedKeys
rs = stmt.getGeneratedKeys();
final Configuration configuration = ms.getConfiguration();
final TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();
final String[] keyProperties = ms.getKeyProperties();
final ResultSetMetaData rsmd = rs.getMetaData();
TypeHandler<?>[] typeHandlers = null;
if (keyProperties != null && rsmd.getColumnCount() >= keyProperties.length) {
for (Object parameter : parameters) {
// there should be one row for each statement (also one for each parameter)
if (!rs.next()) {
break;
}
final MetaObject metaParam = configuration.newMetaObject(parameter);
if (typeHandlers == null) {
//先取得类型处理器
typeHandlers = getTypeHandlers(typeHandlerRegistry, metaParam, keyProperties);
}
//填充键值
populateKeys(rs, metaParam, keyProperties, typeHandlers);
}
}
} catch (Exception e) {
throw new ExecutorException("Error getting generated key or setting result to parameter object. Cause: " + e, e);
} finally {
if (rs != null) {
try {
rs.close();
} catch (Exception e) {
// ignore
}
}
}
}
private TypeHandler<?>[] getTypeHandlers(TypeHandlerRegistry typeHandlerRegistry, MetaObject metaParam, String[] keyProperties) {
TypeHandler<?>[] typeHandlers = new TypeHandler<?>[keyProperties.length];
for (int i = 0; i < keyProperties.length; i++) {
if (metaParam.hasSetter(keyProperties[i])) {
Class<?> keyPropertyType = metaParam.getSetterType(keyProperties[i]);
TypeHandler<?> th = typeHandlerRegistry.getTypeHandler(keyPropertyType);
typeHandlers[i] = th;
}
}
return typeHandlers;
}
private void populateKeys(ResultSet rs, MetaObject metaParam, String[] keyProperties, TypeHandler<?>[] typeHandlers) throws SQLException {
for (int i = 0; i < keyProperties.length; i++) {
TypeHandler<?> th = typeHandlers[i];
if (th != null) {
Object value = th.getResult(rs, i + 1);
metaParam.setValue(keyProperties[i], value);
}
}
}
}