数据准备

CREATE TABLE `user` (`id` int(11) NOT NULL,`username` varchar(30) NOT NULL,`sex` varchar(1) NOT NULL,`birthday` varchar(10) NOT NULL,`address` varchar(100) NOT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

insert into user values(1,"steven","1","1991-02-11","nanjing");
insert into user values(2,"sherry","0","1995-06-14","taizhou");
insert into user values(3,"steven007","1","1995-01-01","nanjing");
insert into user values(4,"sherry007","0","1995-12-31","taizhou");

搭建MyBatis工程

1.使用IDEA创建工程

2.引入项目使用的依赖

mysqlmysql-connector-java5.1.41runtimeorg.mybatismybatis3.2.2

3.Mapper接口开发方式实现原理
Mapper接口开发方式只需要程序员编写Mapper接口即可，由Mybatis框架根据接口定义创建接口的动态代理对象。Mapper接口开发需要遵循以下规范:

• Mapper.xml文件中的namespace与Mapper接口的类路径相同。
• Mapper.xml中定义的statement的id与Mapper接口方法名相同 。
• Mapper.xml中定义的SQL的parameterType与Mapper接口方法的输入参数类型相同。
• Mapper.xml中定义的SQL的resultType与Mapper接口方法的输出参数类型相同。

4.编写MyBatis框架全局配置文件mybatis.xml
在项目目录“/src/main/resources”下新建config目录，并在config目录下新建mybatis.xml文件，具体代码如下。

5.编写po类
在项目目录“/src/main/java/com/steven”下新建po(persistent object)目录，并在po目录下新建User类，具体代码如下。

public class User {//属性名要和数据库表的字段对应private Integer id;private String username;private String sex;private String birthday;private String address;public User() {}public User(Integer id, String username, String sex, String birthday, String address) {this.id = id;this.username = username;this.sex = sex;this.birthday = birthday;this.address = address;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", sex='" + sex + '\'' +", birthday='" + birthday + '\'' +", address='" + address + '\'' +'}';}//get和set方法......
}

6.编写Mapper接口
在项目目录“/src/main/java/com/steven”下新建mapper目录，并在mapper目录下新建UserMapper接口，具体代码如下。

public interface UserMapper {User findUserById(Integer id);
}

7.编写SQL映射
在项目目录“/src/main/resources”下新建mapper目录，并在mapper目录下新建UserMapper.xml文件，具体代码如下。

select * from userwhere id=#{id}

8.编写测试类
在项目目录“/src/test/java”下新建Test类，具体代码如下。

public class Test {public static void main(String[] args) throws Exception {//1.获取MyBatis全局配置文件流String resource = "config/mybatis.xml";InputStream inputStream = Resources.getResourceAsStream(resource);//2.根据MyBatis配置信息创建会话工厂SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);//3.获取会话对象SqlSession sqlSession = sqlSessionFactory.openSession();//4.获取MapperUserMapper userMapper = sqlSession.getMapper(UserMapper.class);//5.业务操作User user = userMapper.findUserById(1);System.out.println(user);sqlSession.close();}
}

User{id=1, username='steven', sex='1', birthday='1991-02-11', address='nanjing'}

9.工程目录