SpringBoot 官方文档示例：(66) JPA的用法

一、引入jpa的starter

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

二、创建数据库表相对应的实体类，其中驼峰和下划线会做自动映射

package cn.edu.tju.domain;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class City {
    @Id
    private int id;
    private String cityName;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getCityName() {
        return cityName;
    }

    public void setCityName(String cityName) {
        this.cityName = cityName;
    }
}

三、创建Repository接口，并按照jpa的规则在其中定义方法：

package cn.edu.tju.repository;

import cn.edu.tju.domain.City;
import org.springframework.data.repository.Repository;

import java.util.List;

@org.springframework.stereotype.Repository
public interface CityRepository extends Repository<City,Integer> {
    List<City> findAll();
    List<City> findByCityName(String name);
}

四、在控制器中注入Repository类

package cn.edu.tju.controller;

import cn.edu.tju.domain.City;
import cn.edu.tju.repository.CityRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.repository.Repository;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class CityController {
    @Autowired
    private CityRepository cityRepository;

    @RequestMapping("/getCityList")
    public List<City> getCityList(){
        List<City> cityList = cityRepository.findAll();
        return cityList;
    }

    @RequestMapping("/getCity/{cityName}")
    public List<City> getCity(@PathVariable("cityName")String cityName){
        List<City> cityList = cityRepository.findByCityName(cityName);
        return cityList;
    }


}

五、示意运行结果

数据库数据如下：