MyBatis学习笔记-Spring集成DAO层实现方式记录

Spring MyBatis 版本如下：

spring                 4.2.6.RELEASE

mybatis                3.4.0

mybatis-spring    1.3.0

Spring集成MyBatis的DAO层两种实现方式如下

第一种基于传统DAO层接口实现类方式：

public interface IUserDAO extends IGenericDAO<User, Long> {}

@Repository("userDAO")public class UserDAOImpl extends GenericDAOImpl<User, Long> implements IUserDAO {}

@Repository("genericDAO")public class GenericDAOImpl<Entity extends Serializable, PK extends Serializable>extends SqlSessionDaoSupport implements IGenericDAO<Entity, PK> {@Resource(name = "sqlSessionTemplate")protected SqlSessionTemplate sqlSessionTemplate = null;public static final String INSERT = "insert";public static final String INSERT_BATCH = "insertBatch";    public static final String UPDATE = "update";    public static final String UPDATE_BATCH = "updateBatch";    public static final String DELETE_BY_PK = "deleteByPK";    public static final String READ_DATA_BY_PK = "readDataByPK";    public static final String READ_DATA_BY_CONDITION = "readDataByCondition";    public static final String READ_DATA_LIST_BY_CONDITION = "readDataListByCondition";    public static final String READ_DATA_PAGINATION_BY_CONDITION = "readDataPaginationByCondition";    public static final String READ_COUNT_BY_CONDITION = "readCountByCondition";private Class<Entity> entityClass = null;@SuppressWarnings("unchecked")public GenericDAOImpl() {        Type type = getClass().getGenericSuperclass();        if (type instanceof ParameterizedType) {            entityClass = (Class<Entity>) ((ParameterizedType) type).getActualTypeArguments()[0];        }}@Override@Resource(name = "sqlSessionTemplate")public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {super.setSqlSessionTemplate(sqlSessionTemplate);}protected SqlSession sqlSession() {return sqlSessionTemplate.getSqlSessionFactory().openSession();}protected void closeSession(SqlSession sqlSession) {if (null != sqlSession) sqlSession.close();}protected SqlSession batchSqlSession() {return sqlSessionTemplate.getSqlSessionFactory().openSession(ExecutorType.BATCH);}protected String obtainSQLID(String sqlId) {Configuration configuration = sqlSessionTemplate.getConfiguration();String dialect = "mysql";if (null != configuration.getVariables()) {dialect = configuration.getVariables().getProperty("dialect");}StringBuffer sb = new StringBuffer();sb.append(dialect).append(".").append(entityClass.getName()).append(".").append(sqlId);return sb.toString();}@Overridepublic void insert(Entity entity) {sqlSessionTemplate.insert(obtainSQLID(INSERT), entity);}@Overridepublic void insert(List<Entity> entities) throws DataException {SqlSession sqlSession = batchSqlSession();for (int i = 0, len = entities.size(); i < len; i++) {sqlSession.insert(obtainSQLID(INSERT), entities.get(i));}sqlSession.flushStatements();closeSession(sqlSession);}@Overridepublic void update(Entity entity) {sqlSessionTemplate.update(obtainSQLID(UPDATE), entity);}@Overridepublic void update(List<Entity> entities) throws DataException {SqlSession sqlSession = batchSqlSession();for (int i = 0, len = entities.size(); i < len; i++) {sqlSession.update(obtainSQLID(UPDATE), entities.get(i));}sqlSession.flushStatements();closeSession(sqlSession);}@Overridepublic void delete(Entity entity) throws DataException {}@Overridepublic void deleteByPK(PK primaryKey) {sqlSessionTemplate.delete(obtainSQLID(DELETE_BY_PK), primaryKey);}@SuppressWarnings("unchecked")@Overridepublic Entity readDataByPK(PK pk) {return (Entity) sqlSessionTemplate.selectOne(obtainSQLID(READ_DATA_BY_PK), pk);}@SuppressWarnings("unchecked")@Overridepublic Entity readDataByCondition(Query query) {Map<String, Object> map = query.getCondition();return (Entity) sqlSessionTemplate.selectOne(obtainSQLID(READ_DATA_BY_CONDITION), map);}@SuppressWarnings("unchecked")@Overridepublic List<Entity> readDataListByCondition(Query query) throws DataException {Map<String, Object> map = query.getCondition();List<Object> resultList = (List<Object>) sqlSessionTemplate.selectList(obtainSQLID(READ_DATA_LIST_BY_CONDITION), map);List<Entity> entities = new ArrayList<Entity>();for (int i = 0, len = resultList.size(); i < len; i++) {entities.add((Entity) resultList.get(i));}return entities;}@SuppressWarnings("unchecked")@Overridepublic QueryResult<Entity> readDataPaginationByCondition(Query query) throws DataException {Map<String, Object> map = query.getCondition();List<Object> resultList = (List<Object>) sqlSessionTemplate.selectList(obtainSQLID(READ_DATA_PAGINATION_BY_CONDITION), map);List<Entity> entities = new ArrayList<Entity>();for (int i = 0, len = resultList.size(); i < len; i++) {entities.add((Entity) resultList.get(i));}int totalRowNum = (Integer) map.get(Query.TOTAL_ROW_NUM);return new QueryResult<Entity>(totalRowNum, entities);}@Overridepublic Long readCountByCondition(Query query) throws DataException {Map<String, Object> map = query.getCondition();return  (Long) sqlSessionTemplate.selectOne(obtainSQLID(READ_COUNT_BY_CONDITION), map);}@Overridepublic void flush() throws DataException {sqlSessionTemplate.clearCache();}}

这里需要注意的是mybatis-spring 1.1.0或是之前版本，可以不用以下代码

@Override@Resource(name = "sqlSessionTemplate")public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {super.setSqlSessionTemplate(sqlSessionTemplate);}

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"><property name="driverClassName" value="${driverClassName}"></property> <property name="url" value="${url}"></property> <property name="username" value="${username}"></property> <property name="password" value="${password}"></property> <property name="initialSize" value="${dbcp.initialSize}"></property> <property name="maxActive" value="${dbcp.maxActive}"></property> <property name="maxIdle" value="${dbcp.maxIdle}"></property> <property name="minIdle" value="${dbcp.minIdle}"></property> <property name="maxWait" value="${dbcp.maxWait}"></property> <property name="removeAbandoned" value="${dbcp.removeAbandoned}"></property> <property name="defaultAutoCommit" value="${dbcp.defaultAutoCommit}"></property> <property name="removeAbandonedTimeout" value="${dbcp.removeAbandonedTimeout}"></property> </bean> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"><property name="dataSource" ref="dataSource" /><property name="typeAliasesPackage" value="org.plat.modules.user.entity" /><property name="configLocation" value="classpath:mybatis/mybatis-config.xml" /><property name="mapperLocations" value="classpath*:org/plat/modules/*/mapper/**/*.xml" /></bean><bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">       <constructor-arg index="0" ref="sqlSessionFactory" /></bean>

typeAliasesPackage的多个选项可以用逗号分隔

<mapper namespace="mysql.org.plat.modules.user.entity.User">

传统DAO层的这种实现方式需要指定对应的SQLID。

第二种基于Mapper接口的动态代理方式：

@Repository("userMapper")public interface UserMapper extends GenericMapper<User, Long> {}

public interface GenericMapper <Entity extends Serializable, PK extends Serializable> {public void insert(Entity entity) throws DataException;public void insert(List<Entity> entities) throws DataException;public void update(Entity entity) throws DataException;public void update(List<Entity> entities) throws DataException;public void delete(Entity entity) throws DataException;public void deleteByPK(PK pk) throws DataException;public Entity readDataByPK(PK pk) throws DataException;public Entity readDataByCondition(Query query) throws DataException;public List<Entity> readDataListByCondition(Query query) throws DataException;public QueryResult<Entity> readDataPaginationByCondition(Query query) throws DataException;public Long readCountByCondition(Query query) throws DataException;public void flush() throws DataException;}

<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">  <property name="basePackage" value="org.plat.modules.*.mapper" />  <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" /></bean>

<mapper namespace="org.plat.modules.user.mapper.UserMapper">

Mappper代理的这种实现方式不需要指定对应的SQLID，接口类里面的方法名字即对应的SQLID，namespace需要指定到对应的Mapper接口。这里需要注意的是MapperScannerConfigurer的配置，可能会遇到无法加载DataSource相关属性的异常，这时候需要配置MapperScannerConfigurer的sqlSessionFactoryBeanName属性，并且检查下有没有配置default-autowire="byName",有的话去掉。