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SpringBoot+Jpa+MySql学习
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上一篇介绍了springboot简单整合mybatis的教程。这一篇是介绍springboot简单整合jpa的教程。
由于jpa的功能强大，后续会继续写关于jpa的介绍已经使用，本文只是简单介绍一下它与springboot的整合。
jpa不需要像mybatis一样创建表，首先给大家看一下application.properties文件代码，其中包含了jpa的配置和数据库配置，尤其注意一下spring.jpa.hibernate.ddl-auto属性，代码如下：
##端口号
server.port=8888
##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
启动类application
package com.dalaoyang;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringbootJpaApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootJpaApplication.class, args);
}
}
pom文件大致和整合mybatis一样，只是把其中的mybatis改成了jpa，代码如下：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.dalaoyang</groupId>
<artifactId>springboot_jpa</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>springboot_jpa</name>
<description>springboot_jpa</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.9.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
实体类city，其中@Table中的name对应数据库中表的名称
package com.dalaoyang.entity;
import javax.persistence.*;
/**
* @author dalaoyang
* @Description
* @project springboot_learn
* @package com.dalaoyang.Entity
* @email 397600342@qq.com
* @date 2018/4/7
*/
@Entity
@Table(name="city")
public class City {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
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;
}
}
然后就是jpa的重要地方，CityRepository，继承了JpaRepository，
由于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。
代码如下：
package com.dalaoyang.repository;
import com.dalaoyang.entity.City;
import org.springframework.data.jpa.repository.JpaRepository;
/**
* @author dalaoyang
* @Description
* @project springboot_learn
* @package com.dalaoyang.Repository
* @email 397600342@qq.com
* @date 2018/4/7
*/
public interface CityRepository extends JpaRepository<City,Integer> {
}
最后是controller，里面和mybatis整合一样，方法上面写的就是对应的测试方法。
package com.dalaoyang.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;
/**
* @author dalaoyang
* @Description
* @project springboot_learn
* @package com.dalaoyang.controller
* @email 397600342@qq.com
* @date 2018/4/7
*/
@RestController
public class CityController {
@Autowired
private CityRepository cityRepository;
//http://localhost:8888/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:8888/deleteCity?cityId=2
@GetMapping(value = "deleteCity")
public String deleteCity(int cityId){
cityRepository.delete(cityId);
return "success";
}
//http://localhost:8888/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:8888/getCityById?cityId=3
@GetMapping(value = "getCityById")
public City getCityById(int cityId){
City city = cityRepository.findOne(cityId);
return city;
}
}
到这里启动项目就可以简单测试一下整合的效果了。
