spring boot使用自动化配置的方式，使得可以很方便、快捷得构建一个spring web应用。作为学习spring boot 的第一课，还是先基于spring boot构建一个简单的包含控制层、服务层以及数据层的hello world应用。
首先确保本机上安装了mysql,本应用会直接访问mysql自带的数据库world。
mysql下载地址：www.mysql.com/downloads/
world数据库:
系统要求：
（1）Intellij Idea 2016.03
注册码传送门：idea.lanyus.com/
（2）Mysql 5.7
（3）Java 1.7以上
构建指南：
（1）在Intellij Idea里面新建HelloWorld project，并在pom.xml文件中添加mysql-connector以及mybatis依赖。
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>6.0.6</version>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.0</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
（2）配置/resources/application.properties数据库参数
spring.datasource.url = jdbc:mysql://localhost:3306/world?useUnicode=true&characterEncoding=UTF-8&autocommit=false&autoReconnect=true&useSSL=false&serverTimezone=UTC
spring.datasource.username = root
spring.datasource.password = root
spring.datasource.driverClassName = com.mysql.jdbc.Driver
（3）根据表city的结构创建city对象
public class City {
private int id;
private String name;
private String countryCode;
private String district;
private int population;
public City(int id ,String name, String countryCode,String district,int population) {
this.id = id;
this.name = name;
this.countryCode=countryCode;
this.district = district;
this.population = population;
}
//setter & getter
}
（4）创建控制层CityController
@RestController
public class CityController {
@Autowired
private CityService cityService;
@RequestMapping(value="/city/{cityName}",method= RequestMethod.GET)
public City gitCity(@PathVariable("cityName") String cityName) {
return cityService.getCityByCityName(cityName);
}
}
（5）创建服务层接口CityService 以及实现类CityServiceImpl
CityService:
public interface CityService {
/**
* get City by its name
* @param cityName
* @return
*/
City getCityByCityName(String cityName);
}
CityServiceImpl:
@Service
public class CityServiceImpl implements CityService{
@Autowired
private CityMapper cityMapper;
@Override
public City getCityByCityName(String cityName) {
return cityMapper.findCityByCityName(cityName);
}
}
（6）创建CityMapper,用于读写数据库表City
@Mapper
public interface CityMapper {
@Select("Select * from city where name=#{cityName}")
City findCityByCityName(String cityName);
}
运行结果
运行主application，在浏览器里面输入http://localhost:8080/city/shanghai，
结果显示如下：
结果显示.png
