SpringBoot2.x-整合JPA（转发）

pom.xml配置

 

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
    </dependencies>

application.properties配置

 

spring.datasource.url=jdbc:mysql://localhost:3306/v_chat?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=123456


# JPA配置
spring.jpa.database=mysql
# 在控制台打印SQL
spring.jpa.show-sql=true
# 数据库平台
spring.jpa.database-platform=mysql
# 每次启动项目时，数据库初始化策略
spring.jpa.hibernate.ddl-auto=update
# 指定默认的存储引擎为InnoDB
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL57Dialect
#遇到大写字母 加”_”的命名, 驼峰命名
spring.jpa.hibernate.naming.physical-strategy=org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy

番外：

　　

ddl-auto:create----每次运行该程序，没有表格会新建表格，表内有数据会清空

ddl-auto:create-drop----每次程序结束的时候会清空表

ddl-auto:update----每次运行程序，没有表格会新建表格，表内有数据不会清空，只会更新

ddl-auto:validate----运行程序会校验数据与数据库的字段类型是否相同，不同会报错

实体类对象

 

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

/**
 * <pre>
 * User -> 用户实体类
 * </pre>
 *
 * @author 撸小鱼
 * Copyright (c) lofish@foxmail.com
 */
@Entity(name = "t_user")
public class User{

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String username;
    private String address;

    public Long getId(){
        return id;
    }

    public void setId( Long id ){
        this.id = id;
    }

    public String getUsername(){
        return username;
    }

    public void setUsername( String username ){
        this.username = username;
    }

    public String getAddress(){
        return address;
    }

    public void setAddress( String address ){
        this.address = address;
    }
}

dao接口定义

 

import net.lofish.xpra.model.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;

import java.util.List;

/**
 * <pre>
 * UserDao -> dao层
 * </pre>
 *
 * @author 撸小鱼
 * Copyright (c) lofish@foxmail.com
 */
public interface UserDao extends JpaRepository<User, Long>{

    List<User> getUserByAddressEqualsAndIdLessThanEqual( String address, Long id );
    
    //SQL nativeQuery的值是true 执行的时候不用再转化
    @Query( value = "select * from t_user where id=(select max(id) from t_user)", nativeQuery = true )
    User maxIdUser();

}

测试

 

@SpringBootTest
class SpringbootXpraApplicationTests{


    @Autowired
    UserDao userDao;


    @Test
    void contextLoads(){
    }


    @Test
    void testUserDao(){
        userDao.getUserByAddressEqualsAndIdLessThanEqual( "abc", 1l );
    }

}

结果

 

Hibernate: select user0_.id as id1_0_, user0_.address as address2_0_, user0_.username as username3_0_ from t_user user0_ where user0_.address=? and user0_.id<=?

按照规范命名方法, jpa自动转换层对应的查询sql语句

Keyword	Sample	JPQL snippet
And	findByLastnameAndFirstname	... where x.lastname = ?1 and x.firstname = ?2
Or	findByLastnameOrFirstname	... where x.lastname = ?1 or x.firstname = ?2
"Is	Equals"	"findByFirstname,findByFirstnameIs,findByFirstnameEquals"	... where x.firstname = ?1
Between	findByStartDateBetween	... where x.startDate between ?1 and ?2
LessThan	findByAgeLessThan	... where x.age < ?1
LessThanEqual	findByAgeLessThanEqual	... where x.age <= ?1
GreaterThan	findByAgeGreaterThan	... where x.age > ?1
GreaterThanEqual	findByAgeGreaterThanEqual	... where x.age >= ?1
After	findByStartDateAfter	... where x.startDate > ?1
Before	findByStartDateBefore	... where x.startDate < ?1
IsNull	findByAgeIsNull	... where x.age is null
"IsNotNull	NotNull"	findByAge(Is)NotNull	... where x.age not null
Like	findByFirstnameLike	... where x.firstname like ?1
NotLike	findByFirstnameNotLike	... where x.firstname not like ?1
StartingWith	findByFirstnameStartingWith	... where x.firstname like ?1?(parameter bound with appended?%)
EndingWith	findByFirstnameEndingWith	... where x.firstname like ?1?(parameter bound with prepended?%)
Containing	findByFirstnameContaining	... where x.firstname like ?1?(parameter bound wrapped in?%)
OrderBy	findByAgeOrderByLastnameDesc	... where x.age = ?1 order by x.lastname desc
Not	findByLastnameNot	... where x.lastname <> ?1
In	findByAgeIn(Collection<Age> ages)	... where x.age in ?1
NotIn	findByAgeNotIn(Collection<Age> ages)	... where x.age not in ?1
TRUE	findByActiveTrue()	... where x.active = true
FALSE	findByActiveFalse()	... where x.active = false
IgnoreCase	findByFirstnameIgnoreCase	... where UPPER(x.firstame) = UPPER(?1)

Repository接口

• CrudRepository 提供CRUD的功能
• PagingAndSortingRepository 提供分页和排序功能
• JpaRepository 提供JPA相关的方法，如刷新持久化数据、批量删除

Spring Data中的每个repository都继承自Repository接口，但是，除此之外，它们每个又有不同的功能

CrudRepository和PagingAndSortingRepository由Spring Data提供；JpaRepository 由Spring Data JPA提供，而Spring Data JPA又是Spring Data的一个子项目
，这就是两者的关系

 

原文链接：https://segmentfault.com/a/1190000022308656