SpringBoot整合JPA

关于JPA和Spring Data JPA详解：Spring Data JPA数据持久化

1、引入依赖

  <!-- mysql驱动 -->
  <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
  </dependency>

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

2、配置application.properties

##端口号
server.port=8080


##数据库配置
##数据库地址
spring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false
##数据库用户名
spring.datasource.username=root
##数据库密码
spring.datasource.password=root
##数据库驱动
spring.datasource.driver-class-name=com.mysql.jdbc.Driver


##validate  加载hibernate时，验证创建数据库表结构
##create   每次加载hibernate，重新创建数据库表结构，这就是导致数据库表数据丢失的原因。
##create-drop        加载hibernate时创建，退出是删除表结构
##update                 加载hibernate自动更新数据库结构
##validate 启动时验证表的结构，不会创建表
##none  启动时不做任何操作
spring.jpa.hibernate.ddl-auto=create

##控制台打印sql
spring.jpa.show-sql=true

3、实体类

　　其中@Table中的name对应数据库中表的名称

package com.echola.entity;

import javax.persistence.*;

@Entity  //标明这是一个实体类
@Table(name="city") //Table配置的属性name指出它银蛇数据库的表，这样实体就映射到对应的表上
public class City {

    @Id  //标注那个属性为表单的主键
    @GeneratedValue(strategy=GenerationType.AUTO) //配置采用何种策略生成主键
    private int cityId;
    private String cityName;
    private String cityIntroduce;

    public City(int cityId, String cityName, String cityIntroduce) {
        this.cityId = cityId;
        this.cityName = cityName;
        this.cityIntroduce = cityIntroduce;
    }

    public City(String cityName, String cityIntroduce) {
        this.cityName = cityName;
        this.cityIntroduce = cityIntroduce;
    }

    public City() {
    }

    public int getCityId() {
        return cityId;
    }

    public void setCityId(int cityId) {
        this.cityId = cityId;
    }

    public String getCityName() {
        return cityName;
    }

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

    public String getCityIntroduce() {
        return cityIntroduce;
    }

    public void setCityIntroduce(String cityIntroduce) {
        this.cityIntroduce = cityIntroduce;
    }
}

4、持久层

　　CityRepository，继承了JpaRepository，本文只是简单介绍了jpa的简单功能，所以JpaRepository中内置的方法已经足够使用。

package com.echola.repository;

import com.dalaoyang.entity.City;
import org.springframework.data.jpa.repository.JpaRepository;

public interface CityRepository extends JpaRepository<City,Integer> {

}

5、控制层

package com.echola.controller;

import com.dalaoyang.entity.City;
import com.dalaoyang.repository.CityRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class CityController {


    @Autowired
    private CityRepository cityRepository;


    //http://localhost:8080/saveCity?cityName=北京&cityIntroduce=中国首都
    @GetMapping(value = "saveCity")
    public String saveCity(String cityName,String cityIntroduce){
        City city = new City(cityName,cityIntroduce);
        cityRepository.save(city);
        return "success";
    }

    //http://localhost:8080/deleteCity?cityId=2
    @GetMapping(value = "deleteCity")
    public String deleteCity(int cityId){
        cityRepository.delete(cityId);
        return "success";
    }

    //http://localhost:8080/updateCity?cityId=3&cityName=沈阳&cityIntroduce=辽宁省省会
    @GetMapping(value = "updateCity")
    public String updateCity(int cityId,String cityName,String cityIntroduce){
        City city = new City(cityId,cityName,cityIntroduce);
        cityRepository.save(city);
        return "success";
    }

    //http://localhost:8080/getCityById?cityId=3
    @GetMapping(value = "getCityById")
    public City getCityById(int cityId){
        City city = cityRepository.findOne(cityId);
        return city;
    }
}