springboot整合JPA(二)

目录

1.在IDEA中新建项目springboot-JPA

2.配置maven环境

3.引入依赖--pom.xml

4.main

4.1 resources配置

4.2 java

4.2.1 启动类--App.class

4.2.2  实体类

4.2.3 定义接口和数据库的交互Dao

4.2.4 service

4.3 测试

4.3.1 执行结果

---

1.在IDEA中新建项目springboot-JPA

2.配置maven环境

        设置--settings出现菜单首页(view-->Appearance-->Toolbar设置完成  查看菜单栏出现🔧)

3.引入依赖--pom.xml

<?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.it.springboot</groupId>
    <artifactId>springboot-JPA</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.mysql.version>8.0.25</project.mysql.version>
        <project.lombok.version>1.18.22</project.lombok.version>
        <project.druid.version>1.2.8</project.druid.version>
        <project.junit.version>4.12</project.junit.version>
        <project.swagger.version>3.0.0</project.swagger.version>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <version>2.5.10</version>
        <artifactId>spring-boot-starter-parent</artifactId>
    </parent>

    <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.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${project.lombok.version}</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${project.mysql.version}</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>${project.druid.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${project.junit.version}</version>
            <scope>test</scope>
        </dependency>

        <!--swagger3 api测试框架-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-boot-starter</artifactId>
            <version>${project.swagger.version}</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

4.main

4.1 resources配置

        application.yml

spring:
  profiles:
    active: dev

        application-dev.yml

server:
  port: 8099

spring:
  datasource:
    druid:
      url: mysql://localhost:3306/mybatis_db?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=UTC&allowPublicKeyRetrieval=true
      username: root
      password:
      driver-class-name: com.mysql.cj.jdbc.Driver
  #json时间处理
  jackson:
    date-format: yyyy-MM-dd HH:mm:ss
    time-zone: GMT+8

  #jpa的配置
    #表已存在 所以注释update
    #true 显示sql语句
  jpa:
    show-sql: true
#    hibernate:
#      ddl-auto: update

#日志
logging:
  level:
    com.it.springboot: debug

4.2 java

4.2.1 启动类--App.class

        建包完成后(com.it.springboot)，立即编写启动类

package com.it.springboot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class App {
    public static void main(String[] args) {
        SpringApplication.run(App.class);
    }
}

4.2.2  实体类

package com.it.springboot.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.*;

@Entity//实体类，为例映射表的特殊类 POJO(简单的Java对象)
@Table(name = "publisher_tab")
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Publisher {
    @Id
    //以数据库的主键策略为主
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "publisher_id")
    private Integer id;
    @Column(name = "publisher_name")
    private String name;
    @Column(name = "publisher_loc")
    private String loc;
}

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;

/**
 *  两表联查  多对一关系@ManyToOne
 */
@Entity
@Table(name = "book_tab")
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "book_id")
    private Integer id;
    @Column(name = "book_isbn")
    private String isbn;
    @Column(name = "book_title")
    private String title;
//    @ManyToOne
//    @JoinColumn(name = "book_publisher")
//    private Publisher publisher;
    //两表中的外键使用 不需要分辨每个表的关系
    @Column(name = "book_publisher")
    private Integer publisher;
}

4.2.3 定义接口和数据库的交互Dao

        JpaRepository是CrudRepository的子接口

        JpaRepository源码

@NoRepositoryBean
public interface JpaRepository<T, ID> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {
    List<T> findAll();

    List<T> findAll(Sort sort);

    List<T> findAllById(Iterable<ID> ids);

    <S extends T> List<S> saveAll(Iterable<S> entities);

    void flush();

    <S extends T> S saveAndFlush(S entity);

    <S extends T> List<S> saveAllAndFlush(Iterable<S> entities);

    /** @deprecated */
    @Deprecated
    default void deleteInBatch(Iterable<T> entities) {
        this.deleteAllInBatch(entities);
    }

    void deleteAllInBatch(Iterable<T> entities);

    void deleteAllByIdInBatch(Iterable<ID> ids);

    void deleteAllInBatch();

    /** @deprecated */
    @Deprecated
    T getOne(ID id);

    T getById(ID id);

    <S extends T> List<S> findAll(Example<S> example);

    <S extends T> List<S> findAll(Example<S> example, Sort sort);
}

        一个实体类对应一个Dao

package com.it.springboot.dao;

import com.it.springboot.entity.Publisher;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;

public interface IPublisherDao extends JpaRepository<Publisher,Integer> {
    //注解自己编写SQl语句   nativeQuery代表原生态的SQL语句
    @Query(value = "SELECT * FROM publisher_tab WHERE publisher_name=?1 AND publisher_loc=?2",nativeQuery = true)
    //JpaRepository源码中不存在的方法  自定义
    Publisher findByNameAndLoc(String name,String loc);
}

package com.it.springboot.dao;

import com.it.springboot.entity.Book;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * 出版社服务于书
 * jpa 一个实体类对应一个接口
 */

public interface IBookDao extends JpaRepository<Book, Integer> {
}

4.2.4 service

package com.it.springboot.service;

import com.it.springboot.entity.Book;
import com.it.springboot.entity.Publisher;

import java.util.List;
import java.util.Optional;

public interface IBookService {
    List<Publisher> findAll();
    Optional<Publisher> findById(int id);
    Publisher findByNameAndLoc(String name,String loc);
    int cnt();//返回出版社的个数
    List<Book> findAllBooks();
}

@Service
@Transactional
public class IBookServiceImpl implements IBookService {
    @Autowired
    private IPublisherDao dao;

    @Autowired
    private IBookDao bookDao;

    @Override
    public List<Publisher> findAll() {
        return dao.findAll();
    }

    @Override
    public Optional<Publisher> findById(int id) {
        return dao.findById(id);
    }

    @Override
    public Publisher findByNameAndLoc(String name, String loc) {
        return dao.findByNameAndLoc(name,loc);
    }


    @Override
    public int cnt() {
        return (int)dao.count();
    }

    @Override
    public List<Book> findAllBooks() {
        return bookDao.findAll();
    }
}

4.3 测试

@RunWith(SpringJUnit4ClassRunner.class)//测试容器
@SpringBootTest
@Slf4j
public class IBookServiceImplTest {
    @Autowired
    private IBookService ibs;

    @Test
    public void findAll() {
        log.debug("findAll-->"+ibs.findAll());
    }

    @Test
    public void findById() {
        log.debug("findById-->"+ibs.findById(2));
    }

    @Test
    public void findByNameAndLoc() {
        log.debug("findByNameAndLoc-->"+ibs.findByNameAndLoc("少儿出版社","碑林"));
    }

    @Test
    public void cnt() {
        log.debug("出版社的个数-->"+ibs.cnt());
    }

    @Test
    public void findAllBooks(){
//        log.debug("findAllBooks-->"+ibs.findAllBooks());
        List<Book> list = ibs.findAllBooks();
        for (Book book : list) {
            //getPublisher--获取Id
            System.out.println(book.getTitle()+book.getPublisher());
        }
    }
}

4.3.1 执行结果

findAll

findById

findByNameAndLoc

count[统计出版社的个数]

 findAllBooks

两表联查--第一种：书记信息对应出版社的Id

两表联查--第二种：书籍标题对应出版社的Id