MyBatis —— 映射文件

SELECT

编写 EmployeeMapper.java

public interface EmployeeMapper {
    public Employee getEmpById(Integer id);
}

编写EmployeeMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.sangyu.mapper.EmployeeMapper">
    <select id="getEmpById" resultType="com.sangyu.bean.Employee">
     select id,last_name,gender,email from tbl_employee where id = #{id}
    </select>
</mapper>

INSERT

编写 EmployeeMapper.java

public interface EmployeeMapper {
    public void addEmp(Employee employee);
}

编写EmployeeMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.sangyu.mapper.EmployeeMapper">
    <!--parameterType，参数类型，可以省略-->
    <insert id="addEmp" parameterType="com.sangyu.bean.Employee">
        insert into tbl_employee(last_name,email,gender) values(#{lastName},#{email},#{gender});
    </insert>
</mapper>

执行测试代码

public class MyBatisTest {
    @Test
    public void Test02() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); 
        SqlSession session = sqlSessionFactory.openSession(); // 获取到的SqlSession不会自动提交收据,openSession(true) 自动提交
        try {
            EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
            Employee employee = new Employee(null,"GIGI","GIGI@aa.com","0");
            mapper.addEmp(employee);
            session.commit(); // 手动提交数据
        } finally {
            session.close();
        }
    }
}

UPDATE

编写 EmployeeMapper.java

public interface EmployeeMapper {
    public void updateEmp(Employee employee);
}

编写EmployeeMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.sangyu.mapper.EmployeeMapper">
    <update id="updateEmp">
        update tbl_employee set last_name = #{lastName},email=#{email},gender=#{gender}
        where id = #{id};
    </update>
</mapper>

DELETE

编写 EmployeeMapper.java

public interface EmployeeMapper {
    public void deleteEmp(Integer id);
}

编写EmployeeMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.sangyu.mapper.EmployeeMapper">
   <delete id="deleteEmp" >
        delete from tbl_employee where id = #{id}
    </delete>
</mapper>

UPDATE增加返回值

Mybatis 允许增删改直接定义以下类型返回值：Integer、Long、Boolean、void

public interface EmployeeMapper {
    public boolean updateEmp(Employee employee);
}

测试

 @Test
    public void Test05() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); 
        SqlSession session = sqlSessionFactory.openSession(); 
        try {
            EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
            Employee employee = new Employee(13,"AA","AA@aa.com","1");
            boolean b = mapper.updateEmp(employee);
            System.out.println(b);
        } finally {
            session.close();
        }
    }

insert 获得自增主键的值

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace：名称空间，对应mapper接口-->
<mapper namespace="com.sangyu.mapper.EmployeeMapper">
    <!--parameterType，参数类型，可以省略 
    mysql 支持自增主键，自增主键值的后取，mybatis 也是利用statement.getGenreatedKeys()；
    useGeneratedKeys="true",使用自增主键值策略 keyProperty="id"-->
    <insert id="addEmp" parameterType="com.sangyu.bean.Employee" useGeneratedKeys="true">
        insert into tbl_employee(last_name,email,gender) values(#{lastName},#{email},#{gender});
    </insert>
</mapper>

执行测试代码

@Test
    public void Test02() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); // 根据xml创建sqlSessionFactory
        SqlSession session = sqlSessionFactory.openSession(true); // 2. 从 SqlSessionFactory 中获取 SqlSession 的实例，SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句
        try {
            // 3. 获取接口的实现类对象
            EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
            Employee employee = new Employee(null,"MIMI","MIMI@aa.com","0");
            mapper.addEmp(employee);
            session.commit(); // 手动提交数据
            System.out.println(employee.getId());
        } finally {
            session.close();
        }
    }