SpringBoot+Jpa+MySql學習

上一篇介紹了springboot簡單整合mybatis的教程。這一篇是介紹springboot簡單整合jpa的教程。

因爲jpa的功能強大，後續會繼續寫關於jpa的介紹已經使用，本文只是簡單介紹一下它與springboot的整合。

jpa不須要像mybatis同樣建立表，首先給你們看一下application.properties文件代碼，其中包含了jpa的配置和數據庫配置，尤爲注意一下spring.jpa.hibernate.ddl-auto屬性，代碼以下：

##端口號
server.port=8888



##數據庫配置
##數據庫地址
spring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false
##數據庫用戶名
spring.datasource.username=root
##數據庫密碼
spring.datasource.password=root
##數據庫驅動
spring.datasource.driver-class-name=com.mysql.jdbc.Driver


##validate 加載hibernate時，驗證建立數據庫表結構
##create 每次加載hibernate，從新建立數據庫表結構，這就是致使數據庫表數據丟失的緣由。
##create-drop 加載hibernate時建立，退出是刪除表結構
##update 加載hibernate自動更新數據庫結構
##validate 啓動時驗證表的結構，不會建立表
##none 啓動時不作任何操做
spring.jpa.hibernate.ddl-auto=create

##控制檯打印sql
spring.jpa.show-sql=true
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啓動類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);
    }
}

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pom文件大體和整合mybatis同樣，只是把其中的mybatis改爲了jpa，代碼以下：

<?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>

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實體類city，其中@Table中的name對應數據庫中表的名稱

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;
    }
}
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而後就是jpa的重要地方，CityRepository，繼承了JpaRepository， 因爲本文只是簡單介紹了jpa的簡單功能，因此JpaRepository中內置的方法已經足夠使用。

代碼以下：

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> {
}
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最後是controller，裏面和mybatis整合同樣，方法上面寫的就是對應的測試方法。

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=中國首都
    @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=瀋陽&cityIntroduce=遼寧省省會
    @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;
    }
}
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到這裏啓動項目就能夠簡單測試一下整合的效果了。