SpringBoot--整合JPA

﹏ヽ暗。殇╰゛Y 2021-08-13 18:33 591阅读 0赞

### SpringBoot整合JPA ###

创建工程并导入依赖

<?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>pers.zhang</groupId>
        <artifactId>springboot_jpa</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>1.5.9.RELEASE</version>
            <relativePath/> 
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-jpa</artifactId>
            </dependency>
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
            </dependency>
    
            
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>1.1.9</version>
            </dependency>
        </dependencies>
    </project>

配置文件

spring:
      datasource:
        type: com.alibaba.druid.pool.DruidDataSource
        url: jdbc:mysql:///chapter05
        username: root
        password: 123456
      jpa:
        show-sql: true #是否打印sql
        database: mysql #JPA对应的数据库
        hibernate:
          ddl-auto: update #无表创建表

实体类

package pers.zhang.entity;
    
    import javax.persistence.*;
    
    /** * @author zhang * @date 2019/12/18 - 21:59 */
    
    /** * @Entity 表示该类是一个实体类，在项目启动时会根据该类自动生成一张表，表的名称即@Entity注解中name的值，如果不配置name，默认表名为类名。 * * 所有的实体类都要有主键，@Id注解表示该属性是一个主键，@GeneratedValue注解表示主键自动生成，strategy表示主键的生成策略。 * * 默认情况下，生成的表中字段名称就是实体类中的属性名称，通过@Column注解可以定制生成的字段名，name可以表示该属性对应的数据表中字段的名称， * nullable表示该字段是否非空 * * @Transient 注解表示在生成数据库中的表时，该属性被忽略，即不生成对应的字段。 */
    @Entity(name = "t_book")
    public class Book { 
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Integer id;
    
        @Column(name = "book_name", nullable = false)//nullable是否非空
        private String name;
    
        private String author;
        private Float price;
    
        @Transient
        private String description;
    
        public Integer getId() { 
            return id;
        }
    
        public void setId(Integer id) { 
            this.id = id;
        }
    
        public String getName() { 
            return name;
        }
    
        public void setName(String name) { 
            this.name = name;
        }
    
        public String getAuthor() { 
            return author;
        }
    
        public void setAuthor(String author) { 
            this.author = author;
        }
    
        public Float getPrice() { 
            return price;
        }
    
        public void setPrice(Float price) { 
            this.price = price;
        }
    
        public String getDescription() { 
            return description;
        }
    
        public void setDescription(String description) { 
            this.description = description;
        }
    
        @Override
        public String toString() { 
            return "Book{" +
                    "id=" + id +
                    ", name='" + name + '\'' +
                    ", author='" + author + '\'' +
                    ", price=" + price +
                    ", description='" + description + '\'' +
                    '}';
        }
    }

Service

package pers.zhang.service;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.data.domain.Page;
    import org.springframework.data.domain.Pageable;
    import org.springframework.stereotype.Service;
    import pers.zhang.dao.BookDao;
    import pers.zhang.entity.Book;
    
    import java.util.List;
    
    /** * @author zhang * @date 2019/12/18 - 22:18 */
    @Service
    public class BookService { 
        @Autowired
        BookDao bookDao;
    
    
        public void addBook(Book book){ 
            bookDao.save(book);
        }
    
        public Page<Book> getBooksByPage(Pageable pageable){ 
            return bookDao.findAll(pageable);
        }
    
        public List<Book> getBooksByAuthorStartingWith(String author){ 
            return bookDao.getBooksByAuthorStartingWith(author);
        }
    
        public List<Book> getBooksByPriceGreaterThan(Float price){ 
            return bookDao.getBooksByPriceGreaterThan(price);
        }
    
        public Book getMaxIdBook(){ 
            return bookDao.getMaxIdBook();
        }
    
        public List<Book> getBookByIdAndAuthor(String author, Integer id){ 
            return bookDao.getBookByIdAndAuthor(author, id);
        }
    
        public List<Book> getBooksByIdandName(String name, Integer id){ 
            return bookDao.getBooksByIdAndName(name, id);
        }
    }

Controller

package pers.zhang.controller;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.data.domain.Page;
    import org.springframework.data.domain.PageRequest;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.GetMapping;
    import pers.zhang.entity.Book;
    import pers.zhang.service.BookService;
    
    import java.util.List;
    
    /** * @author zhang * @date 2019/12/18 - 22:25 */
    @Controller
    public class BookController { 
        @Autowired
        BookService bookService;
    
        @GetMapping("/findAll")
        public void findAll(){ 
            PageRequest pageRequest = new PageRequest(2, 3);
            Page<Book> page = bookService.getBooksByPage(pageRequest);
            System.out.println("总页数：" + page.getTotalPages());
            System.out.println("总记录数：" + page.getTotalElements());
            System.out.println("查询记录：" + page.getContent());
            System.out.println("当前页数：" + (page.getNumber() + 1));
            System.out.println("当前页记录数：" + page.getNumberOfElements());
            System.out.println("每页记录数：" + page.getSize());
        }
    
    
        @GetMapping("/search")
        public void search(){ 
            List<Book> bs1 = bookService.getBookByIdAndAuthor("鲁迅", 7);
            List<Book> bs2 = bookService.getBooksByAuthorStartingWith("吴");
            List<Book> bs3 = bookService.getBooksByIdandName("西", 8);
            List<Book> bs4 = bookService.getBooksByPriceGreaterThan(30f);
            Book b = bookService.getMaxIdBook();
            System.out.println("bs1：" + bs1);
            System.out.println("bs2:" + bs2);
            System.out.println("bs3:" + bs3);
            System.out.println("bs4:" + bs4);
            System.out.println("b:" + b);
        }
    
        @GetMapping("/save")
        public void save(){ 
            Book book = new Book();
            book.setAuthor("鲁迅");
            book.setName("呐喊");
            book.setPrice(23f);
            bookService.addBook(book);
        }
    }

### 测试 ###

访问前表数据如下  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]

访问http://localhost:8080/findAll  
控制台打印：

Hibernate: select book0_.id as id1_0_, book0_.author as author2_0_, book0_.book_name as book_nam3_0_, book0_.price as price4_0_ from t_book book0_ limit ?, ?
    总页数：3
    总记录数：7
    查询记录：[Book{id=7, name='故事新编', author='鲁迅', price=22.0, description='null'}]
    当前页数：3
    当前页记录数：1
    每页记录数：3

访问http://localhost:8080/save  
后台打印：

Hibernate: insert into t_book (author, book_name, price) values (?, ?, ?)

数据表变为：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 1]

访问http://localhost:8080/search  
控制台打印：

Hibernate: select book0_.id as id1_0_, book0_.author as author2_0_, book0_.book_name as book_nam3_0_, book0_.price as price4_0_ from t_book book0_ where book0_.id>? and book0_.author=?
    Hibernate: select book0_.id as id1_0_, book0_.author as author2_0_, book0_.book_name as book_nam3_0_, book0_.price as price4_0_ from t_book book0_ where book0_.author like ?
    Hibernate: select book0_.id as id1_0_, book0_.author as author2_0_, book0_.book_name as book_nam3_0_, book0_.price as price4_0_ from t_book book0_ where book0_.id<? and (book0_.book_name like ?)
    Hibernate: select book0_.id as id1_0_, book0_.author as author2_0_, book0_.book_name as book_nam3_0_, book0_.price as price4_0_ from t_book book0_ where book0_.price>?
    Hibernate: select * from t_book where id = (select max(id) from t_book)
    bs1：[Book{id=8, name='呐喊', author='鲁迅', price=23.0, description='null'}]
    bs2:[Book{id=3, name='西游记', author='吴承恩', price=29.0, description='null'}]
    bs3:[Book{id=3, name='西游记', author='吴承恩', price=29.0, description='null'}]
    bs4:[Book{id=2, name='红楼梦', author='曹雪芹', price=35.0, description='null'}, Book{id=5, name='宋词选注', author='钱钟书', price=33.0, description='null'}]
    b:Book{id=8, name='呐喊', author='鲁迅', price=23.0, description='null'}

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