SpringDataJpa入门
一、SpringDataJpa
1.1、概述
Spring Data JPA 是 Spring 基于 ORM 框架、JPA 规范的基础上封装的一套JPA应用框架，可使开发者用极简的代码即可实现对数据库的访问和操作。它提供了包括增删改查等在内的常用功能，且易于扩展！学习并使用 Spring Data JPA 可以极大提高开发效率！
1.2、SpringDataJpa、Jpa、Hibernate之间的关系
JPA是一套规范，内部是有接口和抽象类组成的。
hibernate是一套成熟的ORM框架，而且Hibernate实现了JPA规范，所以也可以称hibernate为JPA的一种实现方式，我们使用JPA的API编程，意味着站在更高的角度上看待问题（面向接口编程）
Spring Data JPA是Spring提供的一套对JPA操作更加高级的封装，是在JPA规范下的专门用来进行数据持久化的解决方案。
二、SpringDataJpa快速入门
2.1、导入相关的依赖
<?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>cn.waggag.springdatajpa</groupId>
<artifactId>SpringDataJpa_Demo2</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<spring.version>5.0.2.RELEASE</spring.version>
<hibernate.version>5.0.7.Final</hibernate.version>
<slf4j.version>1.6.6</slf4j.version>
<log4j.version>1.2.12</log4j.version>
<c3p0.version>0.9.1.2</c3p0.version>
<mysql.version>8.0.16</mysql.version>
</properties>
<dependencies>
<!-- junit单元测试 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.9</version>
<scope>test</scope>
</dependency>
<!-- spring beg -->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.6.8</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- spring end -->
<!-- hibernate beg -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.2.1.Final</version>
</dependency>
<!-- hibernate end -->
<!-- c3p0 beg -->
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>${c3p0.version}</version>
</dependency>
<!-- c3p0 end -->
<!-- log end -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
<!-- log end -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>1.9.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>4.2.4.RELEASE</version>
</dependency>
<!-- el beg 使用spring data jpa 必须引入 -->
<dependency>
<groupId>javax.el</groupId>
<artifactId>javax.el-api</artifactId>
<version>2.2.4</version>
</dependency>
<dependency>
<groupId>org.glassfish.web</groupId>
<artifactId>javax.el</artifactId>
<version>2.2.4</version>
</dependency>
<!-- el end -->
</dependencies>
</project>2.2、配置Spring的配置文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:task="http://www.springframework.org/schema/task"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/data/jpa
http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">
<!-- 1.dataSource 配置数据库连接池-->
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="driverClass" value="com.mysql.cj.jdbc.Driver" />
<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/jpa?serverTimezone" />
<property name="user" value="waggag" />
<property name="password" value="225514" />
</bean>
<!-- 2.配置entityManagerFactory -->
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<!--配置实体类所在的包-->
<property name="packagesToScan" value="cn.waggag.entity" />
<!--配置jpa的实现方式-->
<property name="persistenceProvider">
<bean class="org.hibernate.jpa.HibernatePersistenceProvider" />
</property>
<!--JPA的供应商适配器-->
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<!--配置是否创建数据库表-->
<property name="generateDdl" value="false" />
<property name="database" value="MYSQL" />
<!--配置数据库方言-->
<property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
<!--是否显示sql-->
<property name="showSql" value="true" />
</bean>
</property>
<property name="jpaDialect">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
</property>
</bean>
<!-- 3.事务管理器-->
<!-- JPA事务管理器 -->
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<!-- 整合spring data jpa-->
<jpa:repositories base-package="cn.waggag.dao"
transaction-manager-ref="transactionManager"
entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>
<!-- 4.txAdvice-->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<tx:method name="save*" propagation="REQUIRED"/>
<tx:method name="insert*" propagation="REQUIRED"/>
<tx:method name="update*" propagation="REQUIRED"/>
<tx:method name="delete*" propagation="REQUIRED"/>
<tx:method name="get*" read-only="true"/>
<tx:method name="find*" read-only="true"/>
<tx:method name="*" propagation="REQUIRED"/>
</tx:attributes>
</tx:advice>
<!-- 5.aop-->
<aop:config>
<aop:pointcut id="pointcut" expression="execution(* cn.waggag.service.*.*(..))" />
<aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" />
</aop:config>
<!--扫描Spring的注解-->
<context:component-scan base-package="cn.waggag"></context:component-scan>
<!--组装其它 配置文件-->
</beans>2.3、编写实体类
package cn.waggag.entity;
import javax.persistence.*;
/**
* 配置实体类和表的映射关系
* 1.实体类和表的映射关系
* @Entity
* @Tavble
* 2.类中属性和表中字段的映射关系
* @Id 配置主键
* @GenerateValue 配置主键生成策略
* @Coulum 配置属性与表的字段的映射
*/
@Entity
@Table(name = "cst_customer")
public class Customer {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "cust_id")
private Long custId;
@Column(name = "cust_name")
private String custName;
@Column(name = "cust_source")
private String custSource;
@Column(name = "cust_industry")
private String custIndustry;
@Column(name = "cust_level")
private String custLevel;
@Column(name = "cust_address")
private String custAddress;
@Column(name = "cust_phone")
private String custPhone;
public Long getCustId() {
return custId;
}
public void setCustId(Long custId) {
this.custId = custId;
}
public String getCustName() {
return custName;
}
public void setCustName(String custName) {
this.custName = custName;
}
public String getCustSource() {
return custSource;
}
public void setCustSource(String custSource) {
this.custSource = custSource;
}
public String getCustIndustry() {
return custIndustry;
}
public void setCustIndustry(String custIndustry) {
this.custIndustry = custIndustry;
}
public String getCustLevel() {
return custLevel;
}
public void setCustLevel(String custLevel) {
this.custLevel = custLevel;
}
public String getCustAddress() {
return custAddress;
}
public void setCustAddress(String custAddress) {
this.custAddress = custAddress;
}
public String getCustPhone() {
return custPhone;
}
public void setCustPhone(String custPhone) {
this.custPhone = custPhone;
}
@Override
public String toString() {
return "Customer{" +
"custId=" + custId +
", custName='" + custName + '\'' +
", custSource='" + custSource + '\'' +
", custIndustry='" + custIndustry + '\'' +
", custLevel='" + custLevel + '\'' +
", custAddress='" + custAddress + '\'' +
", custPhone='" + custPhone + '\'' +
'}';
}
}
2.4、编写符合Spring Data JPA规范的Dao层接口
Spring Data JPA是spring提供的一款对于数据访问层（Dao层）的框架，使用Spring Data JPA，只需要按照框架的规范提供dao接口，不需要实现类就可以完成数据库的增删改查、分页查询等方法的定义，极大的简化了我们的开发过程。
在Spring Data JPA中，对于定义符合规范的Dao层接口，我们只需要遵循以下2点就可以了：
1、创建一个Dao层接口，并实现JpaRepository和JpaSpecificationExecutor
2、提供相应的泛型
package cn.waggag.dao;
import cn.waggag.entity.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
/**
* 符合SpringDataJpa的dao层接口规范
* JpaRepository<操作的实体类类型，实体类中主键属性的类型>
* * 封装了基本CRUD操作
* JpaSpecificationExecutor<操作的实体类类型>
* * 封装了复杂查询（分页）
*/
public interface CustomerDao extends JpaRepository<Customer,Long>, JpaSpecificationExecutor<Customer> {
}
2.5、对Dao基本操作的测试
package cn.waggag.test;
import cn.waggag.dao.CustomerDao;
import cn.waggag.entity.Customer;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class CustomerDaoTest {
@Autowired
private CustomerDao customerDao;
/**
*
*/
@Test
public void testFindOne(){
Customer customer = customerDao.findOne(2L);
System.out.println(customer);
}
/**
* save : 保存或者更新
* 根据传递的对象是否存在主键id，
* 如果没有id主键属性：保存
* 存在id主键属性，根据id查询数据，更新数据
*/
@Test
public void testSave() {
Customer customer = new Customer();
customer.setCustName("程序员");
customer.setCustLevel("vip");
customer.setCustIndustry("itwaggag教育");
customerDao.save(customer);
}
@Test
public void testUpdate() {
Customer customer = new Customer();
customer.setCustId(4L);
customer.setCustName("程序员很厉害");
customerDao.save(customer);
}
@Test
public void testDelete () {
customerDao.delete(3L);
}
/**
* 查询所有
*/
@Test
public void testFindAll() {
List<Customer> list = customerDao.findAll();
for(Customer customer : list) {
System.out.println(customer);
}
}
/**
* 测试统计查询：查询客户的总数量
* count:统计总条数
*/
@Test
public void testCount() {
long count = customerDao.count();//查询全部的客户数量
System.out.println(count);
}
/**
* 测试：判断id为4的客户是否存在
* 1. 可以查询以下id为4的客户
* 如果值为空，代表不存在，如果不为空，代表存在
* 2. 判断数据库中id为4的客户的数量
* 如果数量为0，代表不存在，如果大于0，代表存在
*/
@Test
public void testExists() {
boolean exists = customerDao.exists(4l);
System.out.println("id为4的客户 是否存在："+exists);
}
/**
* 根据id从数据库查询
* @Transactional : 保证getOne正常运行
*
* findOne：
* em.find() :立即加载
* getOne：
* em.getReference :延迟加载
* * 返回的是一个客户的动态代理对象
* * 什么时候用，什么时候查询
*/
@Test
@Transactional
public void testGetOne() {
Customer customer = customerDao.getOne(4l);
System.out.println(customer);
}
}
三、SpringDataJpa执行原理
3.1、SpringDataJpa常用接口分析
JpaRepository：预先定义生成了一些基本的CURD的方法，例如：增、删、改等等继承JpaRepository
JpaSpecificationExecutor：定义了一些特殊的复杂的动态查询
3.2、流程分析
1、通过JdkDynamicAopProxy的invoke方法创建了一个动态代理对象SimpleJpaRepository。
2、SimpleJpaRepository当中封装了JPA的操作（借助JPA的api完成数据库的CRUD）。
3、通过hibernate完成数据库操作（封装了jdbc）。
四、使用Jpql语句
4.1、使用@Query
使用@Query注解，结合JPQL的语句方式完成查询
@Query 注解的使用非常简单，只需在方法上面标注该注解，同时提供一个JPQL查询语句即可
@Query(value = "from Customer where custName = ?")
Customer findJpql(String custName);
/**
* 根据客户名称和客户id查询客户
* jpql： from Customer where custName = ? and custId = ?
*
* 对于多个占位符参数
* 赋值的时候，默认的情况下，占位符的位置需要和方法参数中的位置保持一致
*
* 可以指定占位符参数的位置
* ? 索引的方式，指定此占位的取值来源
*/
@Query(value = "from Customer where custName = ?2 and custId = ?1")
Customer findCustNameAndId(Long id,String name);@Query 来执行一个更新操作，为此，我们需要在使用 @Query 的同时，
@Modifying 来将该操作标识为修改查询，这样框架最终会生成一个更新的操作，而非查询
@Query(value = " update Customer set custName = ?2 where custId = ?1 ")
@Modifying
void updateCustomer(long custId, String custName);4.2、SqpringDataJpa中的Sql查询
/**
* 使用sql的形式查询：
* 查询全部的客户
* sql ： select * from cst_customer;
* Query : 配置sql查询
* value ： sql语句
* nativeQuery ： 查询方式
* true ： sql查询
* false：jpql查询
*
*/
@Query(value = " select * from cst_customer" ,nativeQuery = true)
//@Query(value="select * from cst_customer where cust_name like ?1",nativeQuery = true)
List<Object [] > findSql();
@Query(value="select * from cst_customer where cust_name like ?1",nativeQuery = true)
List<Object [] > findSqlParam(String custName);4.3、方法命名规则查询
方法命名规则查询就是根据方法的名字，就能创建查询。只需要按照Spring Data JPA提供的方法命名规则定义方法的名称，就可以完成查询工作。Spring Data JPA在程序执行的时候会根据方法名称进行解析，并自动生成查询语句进行查询。按照Spring Data JPA 定义的规则，查询方法以findBy开头，涉及条件查询时，条件的属性用条件关键字连接，要注意的是：条件属性首字母需大写。框架在进行方法名解析时，会先把方法名多余的前缀截取掉，然后对剩下部分进行解析。
/**
* 方法名的约定：
* findBy : 查询
* 对象中的属性名（首字母大写） ： 查询的条件
* CustName
* * 默认情况 ： 使用等于的方式查询
* 特殊的查询方式
*
* findByCustName -- 根据客户名称查询
*
* 在springDataJpa的运行阶段
* 会根据方法名称进行解析 findBy from xxx(实体类)
* 属性名称 where custName =
*
* 1.findBy + 属性名称 （根据属性名称进行完成匹配的查询=）
* 2.findBy + 属性名称 + “查询方式（Like | isnull）”
* findByCustNameLike
* 3.多条件查询
* findBy + 属性名 + “查询方式” + “多条件的连接符（and|or）” + 属性名 + “查询方式”
*/
Customer findByCustName(String custName);
//模糊查询
List<Customer> findByCustNameLike(String custName);
//使用客户名称模糊匹配和客户所属行业精准匹配的查询
Customer findByCustNameLikeAndCustIndustry(String custName,String custIndustry);命名规则表格如下表所示：
|
Keyword |
Sample |
JPQL |
||
|
And |
findByLastnameAndFirstname |
… where x.lastname = ?1 and x.firstname = ?2 |
||
|
Or |
findByLastnameOrFirstname |
… where x.lastname = ?1 or x.firstname = ?2 |
||
|
Is,Equals |
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) |
浙公网安备 33010602011771号