springboot项目--数据库配置(使用JpaRepository进行增删改查)

1.首先开启数据库MySQL服务，我用的是xampp管理工具

2.使用sql-front可视化工具新建一个名为‘selldata.sql’的数据库，然后使用以下建表语句建表：

CREATE TABLE `product_category` (
  `category_id`int not null AUTO_INCREMENT,
  `category_name` varchar(64)not null comment'类目名字',
  `category_type` decimal(8,2)not null comment'类目编号',
  `create_time` timestamp not null default current_timestamp comment'创建时间',
  `update_time` timestamp not null default current_timestamp on update current_timestamp
   comment'修改时间',
  PRIMARY KEY (`category_id`),
  UNIQUE KEY `une_category_type` (`category_type`)
)comment'商品表';

下图红色圈出来就是刚才新建的表。

3.在spring项目的pom.xml里添加以下依赖：

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

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

4.在resource目录下创建application.yml文件

用户名、密码、端口号可以改成自己的。

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: laomilaomilaomi
    url: jdbc:mysql://localhost:3399/selldata?serverTimezone=UTC&characterEncoding=utf-8&useSSL=false
  jpa:
    show-sql: true

5.编写封装类ProductCategory.java

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

//类目
@Entity  //表明是一个实体类
public class ProductCategory {
    @Id  //主键
    @GeneratedValue(strategy = GenerationType.IDENTITY)//配置主键自增长
    private Integer categoryId;//类目id
    private String categoryName;//类目名字
    private Integer categoryType;//类目编号

    public Integer getCategoryId() {
        return categoryId;
    }

    public void setCategoryId(Integer categoryId) {
        this.categoryId = categoryId;
    }

    public String getCategoryName() {
        return categoryName;
    }

    public void setCategoryName(String categoryName) {
        this.categoryName = categoryName;
    }

    public Integer getCategoryType() {
        return categoryType;
    }

    public void setCategoryType(Integer categoryType) {
        this.categoryType = categoryType;
    }

    @Override
    public String toString() {
        return "ProductCategory{" +
                "categoryId=" + categoryId +
                ", categoryName='" + categoryName + '\'' +
                ", categoryType=" + categoryType +
                '}';
    }
}

6.编写接口ProductCategoryRepository.java

import com.laomi.sell.dataobject.ProductCategory;
import org.springframework.data.jpa.repository.JpaRepository;
//javascript:void(0)   JpaRepository用法,实现增删改查
public interface ProductCategoryRepository extends JpaRepository<ProductCategory, Integer>  {

}

7.编写测试类

import com.laomi.sell.dataobject.ProductCategory;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ProductCategoryRepositoryTest {

    @Autowired
    private ProductCategoryRepository repository;

//    @Test
//    public void findOneTest(){
//
//        ProductCategory productCategory = repository.findById(1).get();
//        System.out.println(productCategory.toString());
//    }

    @Test
    public void saveTest(){
        ProductCategory productCategory = new ProductCategory();
        productCategory.setCategoryName("最划算");
        productCategory.setCategoryType(1);
        repository.save(productCategory);
    }
}

运行一下这个类，就会发现数据库多了内容

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