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；
我的配置文件如下（desktop_common_sqlMap.xml）：
<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：
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）:
/* * 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; }
转自：http://blog.csdn.net/gaojinshan/article/details/24308313