01.MyBatis入门

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.37</version>
</dependency>
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.3.0</version>
</dependency>

CREATE TABLE  tb_teacher
(
	id              bigint          NOT NULL    auto_increment          COMMENT ‘ID‘,
	no              varchar(10)     NOT NULL                            COMMENT ‘教师编号‘,
	name            varchar(50)     NOT NULL                            COMMENT ‘教师姓名‘,
	sex             char(1)         NOT NULL                            COMMENT ‘教师性别‘,
	job_title       varchar(50)     NOT NULL                            COMMENT ‘职称‘,
	PRIMARY KEY (id)
) COMMENT = ‘教师信息表‘;
INSERT INTO tb_teacher (no, name, sex, job_title) VALUES (‘001‘, ‘Test01‘, ‘f‘, ‘教师01‘);
INSERT INTO tb_teacher (no, name, sex, job_title) VALUES (‘002‘, ‘Test02‘, ‘f‘, ‘教师02‘);
INSERT INTO tb_teacher (no, name, sex, job_title) VALUES (‘003‘, ‘Test03‘, ‘f‘, ‘教师03‘);

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC" />
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver" />
				<property name="url" value="jdbc:mysql://localhost:3306/test" />
				<property name="username" value="root" />
				<property name="password" value="lizhiwei" />
			</dataSource>
		</environment>
	</environments>
	<mappers>
		<mapper resource="mapping/TeacherMapper.xml" />
	</mappers>
</configuration>

<?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="mapping.TeacherDao">
	<select id="getTeacherById" resultType="model.Teacher" parameterType="_int">
		select * from tb_teacher WHERE id = #{id};
	</select>
</mapper>

DataSource dataSource = BlogDataSourceFactory.getBlogDataSource();
TransactionFactory transactionFactory = new JdbcTransactionFactory();
Environment environment = new Environment("development", transactionFactory, dataSource);
Configuration configuration = new Configuration(environment);
configuration.addMapper(BlogMapper.class);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);

Teacher teacher = sqlSession.selectOne("mapping.TeacherDao.getTeacherById",1);
System.out.println(teacher);
sqlSession.close();

package mapping;
import model.Teacher;
public interface TeacherDao
{
    public Teacher getTeacherById(int id);
}

TeacherDao teacherDao = sqlSession.getMapper(TeacherDao.class);
teacher = teacherDao.getTeacherById(2);
System.out.println(teacher);
sqlSession.close();

1. Mapper 接口方法名 和 TeacherMapper.xml中定义的每个 sql 的 id 同名。
   
2. Mapper 接口方法的输入参数类型和 TeacherMapper.xml中定义的 sql parameterType类型相同。
   
3. Mapper 接口的输出参数类型和 TeacherMapper.xml中 定义的 sql 的 resultType类型相同。
   
4. TeacherMapper.xml文件中的 namespace即是 Mapper 接口的类路径。