【转】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">selectnextval('desktop_unlock_tag_id_seq') as id</selectKey>insert intodesktop_unlock_tag(id,name,description,priority)values(#id:INTEGER#,#name:VARCHAR#,#description:VARCHAR#,#priority:INTEGER#)</insert><update id="updateUnlockTagInfo" parameterClass="map">updatedesktop_unlock_tagset modify_time=now(),priority=#priority:INTEGER#,name=#name:VARCHAR#,description=#description:VARCHAR#whereid=#id:INTEGER#</update><delete id="deleteUnlockTagInfo" parameterClass="int">delete fromdesktop_unlock_tagwhere id=#value:INTEGER#</delete><select id="countUnlockTagInfo" resultClass="int">select count(*)fromdesktop_unlock_tag</select><sql id="selectUnlockTagInfo">selectid,name,description,priorityfromdesktop_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 bymodify_time desc limit #size:INTEGER#offset #start:INTEGER#</select>

我的DAO源码如下：

public class UnlockTagDaoImpl extends SqlMapClientDaoSupport implementsUnlockTagDao {@Overridepublic 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;}@Overridepublic 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;}}@Overridepublic 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;}}@Overridepublic UnlockTagInfo findItemById(Integer id) {SqlMapClientTemplate template = this.getSqlMapClientTemplate();UnlockTagInfo item = (UnlockTagInfo) template.queryForObject("DesktopCommon.findUnlockTagInfoById", id);return item;}@Overridepublic 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;
}

 

 

转载自：http://blog.csdn.net/gaojinshan/article/details/24308313

 

转载于:https://www.cnblogs.com/gmq-sh/p/4386598.html

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