步骤:
(1)在pom.xml文件中引入相关依赖;
(2)启动类App.java加@MapperScan注解
(3)在application.properties添加配置文件;
(4)编写User测试类;
(5)编写UserMapper;
(6)编写UserService
(7)编写UserController;

1、加入相关依赖:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.1.RELEASE</version>
</parent>

<properties>
    <java.version>1.7</java.version>
</properties>

<dependencies>
    <!-- spring-boot-starter-web: MVC,AOP的依赖包.... -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <!-- mysql 数据库驱动. -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>

    <!-- spring-boot mybatis依赖 -->
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.1.1</version>
    </dependency>

</dependencies>

2、在 cn.river 包下新建启动类App.java。

加@MapperScan注解(mapper文件在cn.river.mapper包下)

@SpringBootApplication
@MapperScan("cn.river.mapper")
public class App {
 
	public static void main(String[] args) {
		SpringApplication.run(App.class) ;
	}
}

3、在application.properties文件中加入如下数据库配置

########################################################
###datasource  MySQL
########################################################
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.datasource.max-active=20
spring.datasource.max-idle=8
spring.datasource.min-idle=8
spring.datasource.initial-size=10

4、在 cn.river.model 包下新增Model: User.java

public class User {
 
	private Integer id;
	private String name;
	private Integer age;
 
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
 
}

5、在 cn.river.mapper 包下新增UserMapper.java

public interface UserMapper {
 
	@Select("select * from user where id=#{id}")
	public User selectUserById(Integer id) ;
 
	@Select("select * from user where `NAME`=#{name}")
	public User selectUserByName(String name) ;
 
	@Select("select * from user where age=#{age}")
	public List<User> selectUserByAge(Integer age) ;
 
    /**
     * 获取自增长ID
     **/
	@Options(useGeneratedKeys = true, keyProperty = "id", keyColumn = "ID") 
	@Insert("insert into user(`NAME`,AGE) values(#{name},#{age})")
	public void insertUser(User user) ;
}

6、在cn.river.service包下新增UserService.java:

@Service
public class UserService {
 
	@Autowired
	private UserMapper userMapper ;
 
	public User selectUserByName(String name) {
		return userMapper.selectUserByName(name) ;
	}
 
	public User selectUserById(Integer id) {
		return userMapper.selectUserById(id) ;
	}
 
	public List<User> selectUserByAge(Integer age) {
		return userMapper.selectUserByAge(age) ;
	}
 
	public void insertUser(User user) {
		userMapper.insertUser(user) ;
	}
}

7、在cn.river.controller包下新增UserController.java:

@RestController
public class UserController {
 
	@Autowired
	private UserService userService ;
 
	@RequestMapping("user/name")
	public User getUser(String name) {
		User user = userService.selectUserByName(name) ;
		return user ;
	}
 
	@RequestMapping("user/id")
	public User getUser(Integer id) {
		User user = userService.selectUserById(id) ;
		return user ;
	}
 
	@RequestMapping("user/age")
	public List<User> getUserByAge(Integer age) {
		PageHelper.startPage(1, 2) ;
		List<User> users = userService.selectUserByAge(age) ;
		return users ;
	}
 
	@RequestMapping("user/add")
	public User getUserByAge(String name,Integer age) {
		User user = new User() ;
		user.setName(name);
		user.setAge(age);
		userService.insertUser(user) ;
		return user ;
	}
 
}