Spring Boot 系列教程2-Data JPA

Spring Data JPA

用来简化创建 JPA 数据访问层和跨存储的持久层功能。

官网文档连接

http://docs.spring.io/spring-data/jpa/docs/current/reference/html/

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
    Spring Boot 系列教程2-Data JPA_第1张图片

项目图片

Spring Boot 系列教程2-Data JPA_第2张图片

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>4.0.0modelVersion>

    <groupId>com.jege.spring.bootgroupId>
    <artifactId>spring-boot-data-jpaartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <packaging>jarpackaging>

    <name>spring-boot-data-jpaname>
    <url>http://maven.apache.orgurl>

    
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>1.4.1.RELEASEversion>
        <relativePath />
    parent>

    <properties>
        <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
        <java.version>1.8java.version>
    properties>

    <dependencies>

        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-data-jpaartifactId>
        dependency>

        
        <dependency>
            <groupId>com.h2databasegroupId>
            <artifactId>h2artifactId>
            <scope>runtimescope>
        dependency>

        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>

    dependencies>

    <build>
        <finalName>spring-boot-data-jpafinalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>${java.version}source>
                    <target>${java.version}target>
                configuration>
            plugin>
        plugins>
    build>
project>

User.java

package com.jege.spring.boot.data.jpa.entity;

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

/**
 * @author JE哥
 * @email [email protected]
 * @description:jpa模型对象
 */
@Entity
@Table(name = "t_user")
public class User {
  @Id
  @GeneratedValue
  private Long id;
  private String name;
  private Integer age;

  public User() {

  }

  public User(String name, Integer age) {
    this.name = name;
    this.age = age;
  }

  public Long getId() {
    return id;
  }

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

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public Integer getAge() {
    return age;
  }

  public void setAge(Integer age) {
    this.age = age;
  }

}

UserRepository.java

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;

/**
 * @author JE哥
 * @email [email protected]
 * @description:持久层接口,由spring自动生成其实现
 */
public interface UserRepository extends JpaRepository {

  List findByNameLike(String name);

}

Repository接口查询规则

关键字 案例 效果
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 ages) … where x.age in ?1
NotIn findByAgeNotIn(Collection age) … 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)

Application.java

package com.jege.spring.boot;

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

/**
 * @author JE哥
 * @email [email protected]
 * @description:spring boot 启动类
 */

@SpringBootApplication
public class Application {

  public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
  }

}

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

UserRepositoryTest.java

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;

/**
 * @author JE哥
 * @email [email protected]
 * @description:
 */
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest()
public class UserRepositoryTest {
  @Autowired
  UserRepository 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
  @Test
  public void proxy() throws Exception {
    System.out.println(userRepository.getClass());
  }

  @Test
  public void save() throws Exception {
    for (int i = 0; i < 10; i++) {
      User user = new User("jege" + i, 25 + i);
      userRepository.save(user);
    }
  }

  @Test
  public void all() throws Exception {
    save();
    assertThat(userRepository.findAll()).hasSize(10);
  }

  @Test
  public void findByName() throws Exception {
    save();
    assertThat(userRepository.findByNameLike("jege%")).hasSize(10);
  }

  @After
  public void destroy() throws Exception {
    userRepository.deleteAll();
  }

}

源码地址

https://github.com/je-ge/spring-boot

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