【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">
            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（comibatissqlmapclientSqlMapExecutor.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