重温 MyBatis(二) —— 增删改查

驼峰命名自动映射

根据上面的运行结果，我们发现，数据表中的字段 last_name 与类 Emp 中的属性 lastName 不能进行映射。但是 mybatis 为我们提供了字段的驼峰命名转换功能,我们只需要在,mybatis-config.xml 中配置即可

<settings>
    <!-- 使用驼峰命名法转换字段。 -->
    <setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>

运行结果：

增删改

新增

<insert id="insert" parameterType="com.fun.tv.model.Emp">
  insert into bd_emp(id,last_name,gender,email) values(#{id},#{lastName},#{gender},#{email})
</insert>

InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
Emp emp = new Emp();
emp.setLastName("hello");
emp.setGender("1");
emp.setEmail("aaa@163.com");
int result = sqlSession.insert("com.fun.tv.dao.EmpDao.insert", emp);
sqlSession.commit();

修改

<update id="update" parameterType="com.fun.tv.model.Emp">
  update bd_emp set last_name=#{lastName},gender=#{gender},email=#{email} where id=#{id}
</update>

InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
Emp emp = new Emp();
emp.setId(4);
emp.setLastName("world");
emp.setGender("1");
emp.setEmail("aaa@163.com");
int result = sqlSession.update("com.fun.tv.dao.EmpDao.update", emp);
sqlSession.commit();

删除

<delete id="delete" parameterType="int">
  delete from bd_emp where id=#{id}
</delete>

InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
int result = sqlSession.delete("com.fun.tv.dao.EmpDao.delete", 4);
sqlSession.commit();