Spring Boot Data JPA

Spring Data JPA简介

用来简化创建 JPA 数据访问层和跨存储的持久层功能。

Spring Data JPA提供的接口

Repository：最顶层的接口，是一个空的接口，目的是为了统一所有Repository的类型，且能让组件扫描的时候自动识别。

CrudRepository ：是Repository的子接口，提供CRUD的功能。

PagingAndSortingRepository：是CrudRepository的子接口，添加分页和排序的功能。

JpaRepository：是PagingAndSortingRepository的子接口，增加了一些实用的功能，比如：批量操作等。

JpaSpecificationExecutor：用来做负责查询的接口。

Specification：是Spring Data JPA提供的一个查询规范，要做复杂的查询，只需围绕这个规范来设置查询条件即可。

Repository接口查询规则

关键字 @ 案例 @效果

 And @ findByLastnameAndFirstname @ … where x.lastname = ?1 and x.firstname = ?2Or @ findByLastnameOrFirstname @ … where x.lastname = ?1 or x.firstname = ?2
Is,Equals@findByFirstname,findByFirstnameIs,findByFirstnameEquals@… where x.firstname = ?1Between@findByStartDateBetween@… where x.startDate between ?1 and ?2LessThan@findByAgeLessThan@… where x.age < ?1LessThanEqual @findByAgeLessThanEqual@… where x.age <= ?1GreaterThan @findByAgeGreaterThan@… where x.age > ?1GreaterThanEqual @findByAgeGreaterThanEqual@… where x.age >= ?1After @findByStartDateAfter@… where x.startDate > ?1Before@findByStartDateBefore@… where x.startDate < ?1IsNull@findByAgeIsNull@… where x.age is nullIsNotNull,NotNull@findByAge(Is)NotNull@… where x.age not nullLike @findByFirstnameLike@… where x.firstname like ?1NotLike @findByFirstnameNotLike@… where x.firstname not like ?1StartingWith@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 descNot@findByLastnameNot@… where x.lastname <> ?1In @findByAgeIn(Collection<Age> ages)@… where x.age in ?1NotIn @findByAgeNotIn(Collection<Age> age)@… where x.age not in ?1TRUE@findByActiveTrue()@… where x.active = trueFALSE @findByActiveFalse()@… where x.active = falseIgnoreCase@findByFirstnameIgnoreCase@… where                    UPPER(x.firstame) = UPPER(?1)

项目图片

pom.xml

只需要在pom.xml引入需要的数据库配置，就会自动访问此数据库，如果需要配置其他数据库，可以在application.properties进行添加

默认使用org.apache.tomcat.jdbc.pool.DataSource创建连接池

<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.jege.spring.boot</groupId><artifactId>spring-boot-data-jpa</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>spring-boot-data-jpa</name><url>http://maven.apache.org</url><!-- 公共spring-boot配置，下面依赖jar文件不用在写版本号 --><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.4.1.RELEASE</version><relativePath /></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><java.version>1.8</java.version></properties><dependencies><!-- 持久层 --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency><!-- h2内存数据库 --><dependency><groupId>com.h2database</groupId><artifactId>h2</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><build><finalName>spring-boot-data-jpa</finalName><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><configuration><source>${java.version}</source><target>${java.version}</target></configuration></plugin></plugins></build>
</project>

模型对象User

package com.jege.spring.boot.data.jpa.entity;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;/*** @jpa模型对象*/
@Entity
@Table(name = "t_user")
public class User {@Id@GeneratedValueprivate Long id;private String name;private Integer age;public User() {}public User(String name, Integer age) {this.name = name;this.age = age;}}

持久层UserRepository

package com.jege.spring.boot.data.jpa.repository;import java.util.List;import org.springframework.data.jpa.repository.JpaRepository;import com.jege.spring.boot.data.jpa.entity.User;/***持久层接口，由spring自动生成其实现*/
public interface UserRepository extends JpaRepository<User, Long> {List<User> findByNameLike(String name);}

启动类Application

package com.jege.spring.boot;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;/*** spring boot 启动类*/@SpringBootApplication
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}}

配置文件application.properties

## JPA Settings
spring.jpa.generate-ddl: true
spring.jpa.show-sql: true
spring.jpa.hibernate.ddl-auto: create
spring.jpa.properties.hibernate.format_sql: false

测试类UserRepositoryTest

package com.jege.spring.boot.data.jpa;import static org.assertj.core.api.Assertions.assertThat;import org.junit.After;
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.SpringJUnit4ClassRunner;import com.jege.spring.boot.data.jpa.entity.User;
import com.jege.spring.boot.data.jpa.repository.UserRepository;@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest()
public class UserRepositoryTest {@AutowiredUserRepository userRepository;// 打印出class com.sun.proxy.$Proxy66表示spring注入通过jdk动态代理获取接口的子类@Testpublic void proxy() throws Exception {System.out.println(userRepository.getClass());}@Testpublic void save() throws Exception {for (int i = 0; i < 10; i++) {User user = new User("jege" + i, 25 + i);userRepository.save(user);}}@Testpublic void all() throws Exception {save();assertThat(userRepository.findAll()).hasSize(10);}@Testpublic void findByName() throws Exception {save();assertThat(userRepository.findByNameLike("jege%")).hasSize(10);}@Afterpublic void destroy() throws Exception {userRepository.deleteAll();}}

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