MyBatis 之 Annotation

作者：andy

2022-10-27
北京
本文字数：1815 字
阅读完需：约 6 分钟

一、使用 Annotation 实现 CRUD

MyBatis 提供了 Annotation 注解的方式实现固定 SQL 的 CRUD 操作。但是需要注意的是，Java 程序使用 Annotation 有着许多的局限，注解无法实现动态 SQL 功能。

由此，可以编写 CRUD 接口，如下：

package org.fuys.owndb.dao;import java.util.List;import org.apache.ibatis.annotations.Delete;import org.apache.ibatis.annotations.Insert;import org.apache.ibatis.annotations.Param;import org.apache.ibatis.annotations.Select;import org.apache.ibatis.annotations.SelectKey;import org.apache.ibatis.annotations.Update;import org.fuys.owndb.vo.Goal;public interface IGoalDao {
	@Insert("INSERT INTO goal(name,description,start_time,end_time) VALUES(#{name},#{description},#{startTime},#{endTime})")	@SelectKey(before = false, keyProperty = "goalId", resultType = java.lang.String.class, statement = "select last_insert_id()")	public int insert(Goal goal) throws Exception;
	@Update("UPDATE goal SET name=#{name},description=#{description},start_time=#{startTime},end_time=#{endTime} WHERE goalId = #{goalId}")	public int update(Goal goal) throws Exception;
	@Delete("DELETE FROM goal WHERE goalId = #{goalId}")	public int delete(int goalId) throws Exception;
	@Select("SELECT goalId,name,description,start_time AS startTime,end_time AS endTime FROM goal WHERE goalId = #{goalId}")	public Goal selectOne(int goalId) throws Exception;
	@Select("SELECT goalId,name,description,start_time AS startTime,end_time AS endTime FROM goal WHERE name like concat(concat('%',#{name}),'%') and description like concat(concat('%',#{description}),'%')")	public List<Goal> selectList(Goal goal) throws Exception;
	@Select("SELECT goalId,name,description,start_time AS startTime,end_time AS endTime FROM goal WHERE ${column} like concat(concat('%',#{keyword}),'%') LIMIT #{start},#{linesize}")	public List<Goal> selectSplit(@Param("start") int start, @Param("linesize") int linesize, @Param("column") String column,			@Param("keyword") String keyword) throws Exception;
	@Select("SELECT count(goalId) FROM goal WHERE ${column} like concat(concat('%',#{keyword}),'%') ")	public int selectCount(@Param("column") String column, @Param("keyword") String keyword) throws Exception;}

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但是编写了接口，还不够，还需要通过 SqlSessionFactory 获取 org.apache.ibatis.session.Configuration 对象，再由 Configuration 对编写的接口添加注册。流程如下：

SqlSessionFactory --> getConfiguration() --> Configuration --> addMapper()注册

测试部分代码示例如下：

@Test	public void testInsert() throws Exception {		// add mapper		MyBatisSqlSessionFactory.getSqlSessionFactory().getConfiguration().addMapper(IGoalDao.class);		IGoalDao igoalDao = MyBatisSqlSessionFactory.getSqlSession().getMapper(IGoalDao.class);		Goal goal = new Goal();		goal.setName("JJ - " + new Random().nextInt(99));		goal.setDescription("To be singer");		goal.setStartTime(new Date());		goal.setEndTime(new Date());		int len = igoalDao.insert(goal);		MyBatisSqlSessionFactory.getSqlSession().commit();		MyBatisSqlSessionFactory.closeSqlSession();		TestCase.assertEquals(len, 1);		logger.info(String.valueOf(len));		logger.info(goal);	}	@Test	public void testSelectSplit() throws Exception {		// add mapper		MyBatisSqlSessionFactory.getSqlSessionFactory().getConfiguration().addMapper(IGoalDao.class);		IGoalDao igoalDao = MyBatisSqlSessionFactory.getSqlSession().getMapper(IGoalDao.class);		List<Goal> goalList = igoalDao.selectSplit(1, 3, "name", "j");		MyBatisSqlSessionFactory.closeSqlSession();		TestCase.assertNotNull(goalList);		logger.info(goalList);	}

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综上所述，接口的子类可以通过注解来实现，但是，因为注解的方式无法实现动态 SQL，建议最好使用配置文件的方式进行开发。

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MyBatis 之 Annotation

一、使用 Annotation 实现 CRUD

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