Mybatis/Ibatis，数据库操作的返回值

该问题，我百度了下，根本没发现什么有价值的文章；还是看源代码（详见最后附录）中的注释，最有效了！
insert，返回值是：新插入行的主键（primary key）；需要包含<selectKey>语句，才会返回主键，否则返回值为null。
update/delete，返回值是：更新或删除的行数；无需指明resultClass；但如果有约束异常而删除失败，只能去捕捉异常。
queryForObject，返回的是：一个实例对象或null；需要包含<select>语句，并且指明resultMap；
queryForList，返回的是：实例对象的列表；需要包含<select>语句，并且指明resultMap；

<!-- 插入并返回主键Id --><insert id="insertReturnId"  parameterType="autocodeDistribute">  <selectKey keyProperty="afId" resultType="java.lang.Integer" order="AFTER">SELECT LAST_INSERT_ID()  </selectKey>  insert into basic_autocode_format_distribute(af_name,creater,create_date,updater,update_date)   values(#{afName},#{creater},#{createDate},#{updater},#{updateDate})    </insert>

我的配置文件如下（desktop_common_sqlMap.xml）：

[html] view plaincopy在CODE上查看代码片派生到我的代码片

<typeAlias alias="UnlockTagInfo" type="com.desktop.common.bean.UnlockTagInfo" />
<resultMap class="UnlockTagInfo" id="UnlockTagInfoResult">
<result column="id" property="id" jdbcType="INTEGER" />
<result column="name" property="name" jdbcType="VARCHAR" />
<result column="description" property="description" jdbcType="VARCHAR" />
<result column="priority" property="priority" jdbcType="INTEGER" />
</resultMap>
<insert id="insertUnlockTagInfo" parameterClass="map">
<selectKey resultClass="int" keyProperty="id">
select
nextval('desktop_unlock_tag_id_seq') as id
</selectKey>
insert into
desktop_unlock_tag(id,name,description,priority)
values(#id:INTEGER#,#name:VARCHAR#,#description:VARCHAR#,#priority:INTEGER#)
</insert>
<update id="updateUnlockTagInfo" parameterClass="map">
update
desktop_unlock_tag
set modify_time=now(),priority=#priority:INTEGER#,
name=#name:VARCHAR#,description=#description:VARCHAR#
where
id=#id:INTEGER#
</update>
<delete id="deleteUnlockTagInfo" parameterClass="int">
delete from
desktop_unlock_tag
where id=#value:INTEGER#
</delete>
<select id="countUnlockTagInfo" resultClass="int">
select count(*)
from
desktop_unlock_tag
</select>
<sql id="selectUnlockTagInfo">
select
id,name,description,priority
from
desktop_unlock_tag
</sql>
<select id="findUnlockTagInfoById" parameterClass="int"
resultMap="UnlockTagInfoResult">
<include refid="selectUnlockTagInfo" />
where id=#id:INTEGER#
</select>
<select id="listUnlockTagInfo" parameterClass="map"
resultMap="UnlockTagInfoResult">
<include refid="selectUnlockTagInfo" />
order by
modify_time desc limit #size:INTEGER#
offset #start:INTEGER#
</select>

我的DAO源码如下：
[java] view plaincopy在CODE上查看代码片派生到我的代码片

public class UnlockTagDaoImpl extends SqlMapClientDaoSupport implements
UnlockTagDao {
@Override
public Integer addItem(String name, String desc, Integer priority) {
SqlMapClientTemplate template = this.getSqlMapClientTemplate();
Map<String, Object> args = new HashMap<String, Object>();
args.put("name", name);
args.put("description", desc);
args.put("priority", priority);
Object key = template.insert("DesktopCommon.insertUnlockTagInfo", args);
return (Integer) key;
}

@Override
public boolean updateItem(Integer id, String name, String description,
Integer priority) {
SqlMapClientTemplate template = this.getSqlMapClientTemplate();
Map<String, Object> args = new HashMap<String, Object>();
args.put("id", id);
args.put("name", name);
args.put("description", description);
args.put("priority", priority);
try {
int c = template.update("DesktopCommon.updateUnlockTagInfo", args);
if (c > 0) {
return true;
}
return false;
} catch (Exception e) {
return false;
}
}

@Override
public boolean deleteItem(Integer id) {
SqlMapClientTemplate template = this.getSqlMapClientTemplate();
try {
int c = template.delete("DesktopCommon.deleteUnlockTagInfo", id);
if (c > 0) {
return true;
}
return false;
} catch (Exception e) {
return false;
}
}

@Override
public UnlockTagInfo findItemById(Integer id) {
SqlMapClientTemplate template = this.getSqlMapClientTemplate();
UnlockTagInfo item = (UnlockTagInfo) template.queryForObject(
"DesktopCommon.findUnlockTagInfoById", id);
return item;
}

@Override
public PagedList<UnlockTagInfo> listAll(Integer nStart, Integer nSize,
boolean bCountTotal) {
SqlMapClientTemplate template = this.getSqlMapClientTemplate();
PagedList<UnlockTagInfo> result = new PagedList<UnlockTagInfo>();
if (bCountTotal) {
int total = (Integer) template
.queryForObject("DesktopCommon.countUnlockTagInfo");
result.setTotal(total);
}
Map<String, Integer> args = new HashMap<String, Integer>();
args.put("start", nStart);
args.put("size", nSize);
@SuppressWarnings("unchecked")
List<UnlockTagInfo> items = template.queryForList(
"DesktopCommon.listUnlockTagInfo", args);
result.setData(items);
return result;
}
}


关于ibatis的接口，参见其源码（com\ibatis\sqlmap\client\SqlMapExecutor.java）:

[java] view plaincopy在CODE上查看代码片派生到我的代码片

/*
* Copyright 2004 Clinton Begin
*
* 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 com.ibatis.sqlmap.client;

import com.ibatis.common.util.PaginatedList;
import com.ibatis.sqlmap.client.event.RowHandler;
import com.ibatis.sqlmap.engine.execution.BatchException;

import java.sql.SQLException;
import java.util.List;
import java.util.Map;

/**
* This interface declares all methods involved with executing statements
* and batches for an SQL Map.
*
* @see SqlMapSession
* @see SqlMapClient
*/
public interface SqlMapExecutor {

/**
* Executes a mapped SQL INSERT statement.
* Insert is a bit different from other update methods, as it
* provides facilities for returning the primary key of the
* newly inserted row (rather than the effected rows). This
* functionality is of course optional.
* <p/>
* The parameter object is generally used to supply the input
* data for the INSERT values.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return The primary key of the newly inserted row. This might be automatically
* generated by the RDBMS, or selected from a sequence table or other source.
* @throws java.sql.SQLException If an error occurs.
*/
Object insert(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL INSERT statement.
* Insert is a bit different from other update methods, as it
* provides facilities for returning the primary key of the
* newly inserted row (rather than the effected rows). This
* functionality is of course optional.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id The name of the statement to execute.
* @return The primary key of the newly inserted row. This might be automatically
* generated by the RDBMS, or selected from a sequence table or other source.
* @throws java.sql.SQLException If an error occurs.
*/
Object insert(String id) throws SQLException;

/**
* Executes a mapped SQL UPDATE statement.
* Update can also be used for any other update statement type,
* such as inserts and deletes. Update returns the number of
* rows effected.
* <p/>
* The parameter object is generally used to supply the input
* data for the UPDATE values as well as the WHERE clause parameter(s).
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return The number of rows effected.
* @throws java.sql.SQLException If an error occurs.
*/
int update(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL UPDATE statement.
* Update can also be used for any other update statement type,
* such as inserts and deletes. Update returns the number of
* rows effected.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id The name of the statement to execute.
* @return The number of rows effected.
* @throws java.sql.SQLException If an error occurs.
*/
int update(String id) throws SQLException;

/**
* Executes a mapped SQL DELETE statement.
* Delete returns the number of rows effected.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the DELETE statement.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return The number of rows effected.
* @throws java.sql.SQLException If an error occurs.
*/
int delete(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL DELETE statement.
* Delete returns the number of rows effected.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id The name of the statement to execute.
* @return The number of rows effected.
* @throws java.sql.SQLException If an error occurs.
*/
int delete(String id) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a single object instance.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return The single result object populated with the result set data,
* or null if no result was found
* @throws java.sql.SQLException If more than one result was found, or if any other error occurs.
*/
Object queryForObject(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a single object instance.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id The name of the statement to execute.
* @return The single result object populated with the result set data,
* or null if no result was found
* @throws java.sql.SQLException If more than one result was found, or if any other error occurs.
*/
Object queryForObject(String id) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* the supplied result object.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param resultObject The result object instance that should be populated with result data.
* @return The single result object as supplied by the resultObject parameter, populated with the result set data,
* or null if no result was found
* @throws java.sql.SQLException If more than one result was found, or if any other error occurs.
*/
Object queryForObject(String id, Object parameterObject, Object resultObject) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return A List of result objects.
* @throws java.sql.SQLException If an error occurs.
*/
List queryForList(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id The name of the statement to execute.
* @return A List of result objects.
* @throws java.sql.SQLException If an error occurs.
*/
List queryForList(String id) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects within a certain range.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param skip The number of results to ignore.
* @param max The maximum number of results to return.
* @return A List of result objects.
* @throws java.sql.SQLException If an error occurs.
*/
List queryForList(String id, Object parameterObject, int skip, int max) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects within a certain range.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id The name of the statement to execute.
* @param skip The number of results to ignore.
* @param max The maximum number of results to return.
* @return A List of result objects.
* @throws java.sql.SQLException If an error occurs.
*/
List queryForList(String id, int skip, int max) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns a number of
* result objects that will be handled one at a time by a
* RowHandler.
* <p/>
* This is generally a good approach to take when dealing with large sets
* of records (i.e. hundreds, thousands...) that need to be processed without
* eating up all of the system resources.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param rowHandler A RowHandler instance
* @throws java.sql.SQLException If an error occurs.
*/
void queryWithRowHandler(String id, Object parameterObject, RowHandler rowHandler) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns a number of
* result objects that will be handled one at a time by a
* RowHandler.
* <p/>
* This is generally a good approach to take when dealing with large sets
* of records (i.e. hundreds, thousands...) that need to be processed without
* eating up all of the system resources.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id The name of the statement to execute.
* @param rowHandler A RowHandler instance
* @throws java.sql.SQLException If an error occurs.
*/
void queryWithRowHandler(String id, RowHandler rowHandler) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects a page at a time.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param pageSize The maximum number of result objects each page can hold.
* @return A PaginatedList of result objects.
* @throws java.sql.SQLException If an error occurs.
* @deprecated All paginated list features have been deprecated
*/
PaginatedList queryForPaginatedList(String id, Object parameterObject, int pageSize) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects a page at a time.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id The name of the statement to execute.
* @param pageSize The maximum number of result objects each page can hold.
* @return A PaginatedList of result objects.
* @throws java.sql.SQLException If an error occurs.
* @deprecated All paginated list features have been deprecated
*/
PaginatedList queryForPaginatedList(String id, int pageSize) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects that will be keyed into a Map.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param keyProp The property to be used as the key in the Map.
* @return A Map keyed by keyProp with values being the result object instance.
* @throws java.sql.SQLException If an error occurs.
*/
Map queryForMap(String id, Object parameterObject, String keyProp) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects from which one property will be keyed into a Map.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param keyProp The property to be used as the key in the Map.
* @param valueProp The property to be used as the value in the Map.
* @return A Map keyed by keyProp with values of valueProp.
* @throws java.sql.SQLException If an error occurs.
*/
Map queryForMap(String id, Object parameterObject, String keyProp, String valueProp) throws SQLException;

/**
* Starts a batch in which update statements will be cached before being sent to
* the database all at once. This can improve overall performance of updates update
* when dealing with numerous updates (e.g. inserting 1:M related data).
*
* @throws java.sql.SQLException If the batch could not be started.
*/
void startBatch() throws SQLException;

/**
* Executes (flushes) all statements currently batched.
*
* @return the number of rows updated in the batch
* @throws java.sql.SQLException If the batch could not be executed or if any of the statements
* fails.
*/
int executeBatch() throws SQLException;

/**
* Executes (flushes) all statements currently batched.
*
* @return a List of BatchResult objects. There will be one element in the
* list for each sub-batch executed. A sub-batch is created by adding a statement
* to the batch that does not equal the prior statement.
* @throws SQLException if a database access error occurs, or the drive
* does not support batch statements
* @throws BatchException if the driver throws BatchUpdateException
* @see com.ibatis.sqlmap.engine.execution.BatchException
*/
List executeBatchDetailed() throws SQLException, BatchException;
}