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。
