SpringDataJPA（一）SpringDataJPA的简单使用

今天药忘吃喽~ 2022-01-07 08:01 389阅读 0赞

## 源码 ##

**GitHub：** [https://github.com/291685399/springboot-learning/tree/master/springboot-springdatajpa01][https_github.com_291685399_springboot-learning_tree_master_springboot-springdatajpa01]

## SpringDataJPA是什么？ ##

SpringDataJPA是Spring提供的持久层的解决方案，Spring Data JPA旨在通过减少实际需要的工作量来显着改善数据访问层的实现

## SpringDataJPA、Mybatis和Hibernate之间的关系 ##

在讲三者的关系之前，先说一下JPA。JPA是一种Java规范，是ORM框架的标准。而ORM的思想是在应用程序和JDBC API中引入一个中间层用于解决数据库字段与对象之间的对应。

**关系：**  
1、 三者都是持久层框架  
2、 SpringDataJPA和Hibernate是JPA规范的实现，都是ORM框架，Mybatis是半ORM框架  
3、 SpringDataJPA和Hibernate中都有默认的方法实现，直接调用即可操作数据库，而Mybatis则需要配置xml文件，在开发量上更大。虽然在Mybatis之前出现了TkMybatis和Mybatis-Plus等框架，其主要目的都是简化Mybatis的开发量，其中都提供了增删改查的方法。

## 简单使用SpringDataJPA ##

**pom.xml：**

<dependencies>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </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>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
    </dependencies>

**application.properties：**

# datasource
    spring.datasource.url=jdbc:mysql://127.0.0.1:3306/springboot-springdatajpa01?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
    spring.datasource.driver-class-name=com.mysql.jdbc.Driver
    spring.datasource.username=root
    spring.datasource.password=root
    # springdatajpa
    #打印出自动生产的SQL，方便调试的时候查看
    spring.jpa.show-sql=true
    #更新数据库表结构
    spring.jpa.hibernate.ddl-auto=update
    #对打印的sql进行格式化，方便查看
    spring.jpa.properties.hibernate.format_sql=true
    spring.jpa.properties.hibernate.use_sql_comments=true
    #指定生成表名的存储引擎为InneoDB
    spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect

**User：**

@Entity
    @Data
    public class User { 
        @Id
        @GeneratedValue
        private Long id;
        private String name;
        private Integer age;
        private String sex;
        private String address;
    }

*  继承CrudRepository

**UserCrudRepository：**

public interface UserCrudRepository extends CrudRepository<User, Long> { 
    }

**UserCrudRepositoryTests：**

@RunWith(SpringRunner.class)
    @SpringBootTest
    public class UserCrudRepositoryTests { 
    
        @Autowired
        private UserCrudRepository userCrudRepository;
    
        /** * 新增 */
        @Test
        public void add() { 
            User user = new User();
            user.setName("ljk2");
            user.setSex("1");
            user.setAge(18);
            user.setAddress("beijing");
            User result = userCrudRepository.save(user);
            Assert.assertNotNull(result);
        }
    
        /** * 修改 */
        @Test
        public void edit() { 
            User user = new User();
            user.setId(1l);
            user.setName("ljk2edit");
            user.setSex("1");
            user.setAge(18);
            user.setAddress("beijing");
            User result = userCrudRepository.save(user);
            Assert.assertNotNull(result);
        }
    
        /** * 根据id查询 */
        @Test
        public void findById() { 
            Optional<User> userOptional = userCrudRepository.findById(1L);
            User result = userOptional.get();
            System.out.println(result);
        }
    
        /** * 查询所有 */
        @Test
        public void findAll() { 
            List<User> userList = (List<User>) userCrudRepository.findAll();
            System.out.println(userList);
        }
    
        /** * 计算总数 */
        @Test
        public void count() { 
            long count = userCrudRepository.count();
            System.out.println(count);
        }
    
    }

*  继承PagingAndSortingRepository

**UserPageRepository：**

/** * 他是具有分页和排序的功能 同时继承了 CrudRepository */
    public interface UserPageRepository extends PagingAndSortingRepository<User,Long> { 
    }

**UserPageRepositoryTests：**

@RunWith(SpringRunner.class)
    @SpringBootTest
    public class UserPageRepositoryTests { 
    
        @Autowired
        private UserPageRepository userPageRepository;
    
        /** * 排序查询 */
        @Test
        public void findAllBySort() { 
            List<User> userList = (List<User>) userPageRepository.findAll(new Sort(Sort.Direction.ASC, "age"));
            System.out.println(userList.size());
            System.out.println(userList);
        }
    
        /** * 分页查询 */
        @Test
        public void findAllByPageable() { 
            Page<User> userPage = userPageRepository.findAll(new PageRequest(0, 20));
            userPage.getNumber();//页数
            userPage.getContent();//分页的数据
            userPage.getTotalPages();//总共的页数
            System.out.println("number:" + userPage.getNumber()
                    + "Countet" + userPage.getContent().size()
                    + "TotalPages" + userPage.getTotalPages());
        }
    
    }

*  继承JpaRepository

**UserJpaRepository：**

/** * 不仅继承了 PagingAndSortingRepository 同时继承了 QueryByExampleExecutor（示例匹配器） */
    public interface UserJpaRepository extends JpaRepository<User, Long> { 
    }

**UserJpaRepositoryTests：**

@RunWith(SpringRunner.class)
    @SpringBootTest
    public class UserJpaRepositoryTests { 
    
        @Autowired
        private UserJpaRepository userJpaRepository;
    
        /** * 执行秒数：49422 49145 * 批量插入数据 */
        @Test
        public void BatchSave() { 
            long startTime = System.currentTimeMillis();
            List<User> list = new ArrayList<User>();
            for (int i = 0; i < 60000; i++) { 
                User user = new User();
                user.setName("ljk" + i);
                user.setAge(i);
                user.setAddress("address" + i);
                list.add(user);
                if (i % 100 == 0) { 
                    userJpaRepository.saveAll(list);
                    list.clear();
                }
            }
            long endTime = System.currentTimeMillis();
            System.out.println("执行秒数：" + (endTime - startTime));
        }
    
        /** * 执行秒数：48053 48394 执行速度比BatchSave 要快 * 批量保存数据 （高效处理方式）减少大事物的提交 */
        @Test
        public void BatchSaveBest() { 
            long startTime = System.currentTimeMillis();
            List<User> list = new ArrayList<User>();
            for (int i = 0; i < 60000; i++) { 
                User user = new User();
                user.setName("ljk" + i);
                list.add(user);
                if (i % 100 == 0) { 
                    userJpaRepository.saveAll(list);
                    userJpaRepository.flush();
                    list.clear();
                }
            }
            long endTime = System.currentTimeMillis();
            System.out.println("执行秒数：" + (endTime - startTime));
        }
    
        /** * 查询所有数据 */
        @Test
        public void findAll() { 
            List<User> userlists = userJpaRepository.findAll();
            Assert.assertTrue(userlists.size() > 0);
        }
    
        /** * 根据 age 排序查询 */
        @Test
        public void findALLSortAge() { 
            List<User> lists = userJpaRepository.findAll(Sort.by(Sort.Direction.ASC, "age"));
            for (User list : lists) { 
                System.out.println(list);
            }
        }
    
        /** * 分页查询 */
        @Test
        public void findAllByPage() { 
            PageRequest pageRequest = new PageRequest(0, 1);
            Page<User> userPage = userJpaRepository.findAll(pageRequest);
            Assert.assertTrue(userPage.getContent().size() == 1);
        }
    
        /** * 分页排序查询 */
        @Test
        public void findAllByPageAndSort() { 
            PageRequest pageRequest = new PageRequest(0, 3, Sort.by(Sort.Direction.ASC, "age"));
            Page<User> userPage = userJpaRepository.findAll(pageRequest);
            List<User> userList = userPage.getContent();
            for (User user : userList) { 
                System.out.println(user);
            }
        }
    
        /** * 根据id 的集合获取所有数据 */
        @Test
        public void findAllByIds() { 
            List<Long> ids = new ArrayList<Long>();
            ids.add(1L);
            ids.add(2L);
            ids.add(3L);
            ids.add(4L);
            List<User> userList = userJpaRepository.findAllById(ids);
            System.out.println(userList);
        }
    
        /** * 批量删除所有数据 */
        @Test
        public void deleteAllInBatch() { 
            userJpaRepository.deleteAllInBatch();
        }
    
        /** * 保存数据并刷新缓存 */
        @Test
        public void saveAndFlush() { 
            User user = new User();
            user.setName("ljk");
            user.setAge(18);
            user.setAddress("beijing");
            user.setSex("1");
            User result = userJpaRepository.saveAndFlush(user);
            Assert.assertNotNull(result);
        }
    
        /** * 批量删除 */
        @Test
        public void deleteInBatch() { 
            List<User> userList = new ArrayList<User>();
            User user = new User();
            user.setId(1l);
            userList.add(user);
            User user2 = new User();
            user2.setId(2l);
            userList.add(user2);
            User user3 = new User();
            user3.setId(3l);
            userList.add(user3);
            User user4 = new User();
            user4.setId(4l);
            userList.add(user4);
            userJpaRepository.deleteInBatch(userList);
        }
    
        /** * 根据id 获取数据 */
        @Test
        public void getOne() { 
            User user = userJpaRepository.findById(1L).get();
            System.out.println(user);
        }
    
        /** * 示例匹配器 ExampleMatcher */
        @Test
        public void findUserByExam() { 
            User user = new User();
            user.setName("ljk");
            List<User> list = userJpaRepository.findAll(Example.of(user));
            System.out.println(list);
        }
    
        /** * 模糊查询 */
        @Test
        public void findUserByExamQuery() { 
            User user = new User();
            user.setName("ljk");
            user.setAddress("beijing");
            user.setAge(18);
            ExampleMatcher matcher = ExampleMatcher.matching()
                    .withMatcher("name", ExampleMatcher.GenericPropertyMatchers.startsWith())//模糊查询匹配开头，即{username}%
                    .withMatcher("address", ExampleMatcher.GenericPropertyMatchers.contains())//全部模糊查询，即%{address}%
                    .withIgnorePaths("id");//忽略字段，即不管id是什么值都不加入查询条件
            Example<User> example = Example.of(user, matcher);
            List<User> userList = userJpaRepository.findAll(example);
            System.out.println(userList);
        }
    }

[https_github.com_291685399_springboot-learning_tree_master_springboot-springdatajpa01]: https://github.com/291685399/springboot-learning/tree/master/springboot-springdatajpa01