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Spring的学习笔记(十六)——SpringDataJpa配置和相关的操作

Nick · 5月4日 · 2020年 · · 本文16106字 · 阅读41分钟712

@TOC

springDataJpa的概述

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!

Spring Data JPA 让我们解脱了DAO层的操作,基本上所有CRUD都可以依赖于它来实现,在实际的工作工程中,推荐使用Spring Data JPA + ORM(如:hibernate)完成操作,这样在切换不同的ORM框架时提供了极大的方便,同时也使数据库层操作更加简单,方便解耦

springDataJpa的入门操作

案例:客户的基本CRUD

i.搭建环境

创建工程导入坐标

<?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.kt</groupId>
    <artifactId>springdata_jpa</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <spring.version>4.2.4.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>5.1.6</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>

配置spring的配置文件(applicationContext.xml配置spring Data jpa的整合)

<?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.jdbc.Driver"/>
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/jpa"/>
        <property name="user" value="root"/>
        <property name="password" value="root"/>
    </bean>

    <!-- 2.配置entityManagerFactory -->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="packagesToScan" value="cn.kt.domain"/>
        <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"/>
                <!--指定数据库类型-->
                <property name="database" value="MYSQL"/>
                <!--数据库方言,支持特有的语法-->
                <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect"/>
                <!--是否显示sql语句-->
                <property name="showSql" value="true"/>
            </bean>
        </property>
        <!--jpa的方言,高级的特性-->
        <property name="jpaDialect">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"/>
        </property>
    </bean>

    <!-- 整合spring data jpa-->
    <jpa:repositories base-package="cn.kt.dao"
                      transaction-manager-ref="transactionManager"
                      entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>


    <!-- 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>


    <!-- 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.kt.service.*.*(..))"/>
        <aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut"/>
    </aop:config>
    <!--配置包扫描-->
    <context:component-scan base-package="cn.kt "></context:component-scan>

    <!--组装其它 配置文件-->

</beans>

编写实体类(Customer),使用jpa注解配置映射关系

package cn.kt.domain;/*
 *Created by tao on 2020-05-04.
 */

import javax.persistence.*;
import java.io.Serializable;

@Entity //声明实体类
@Table(name = "cst_customer") //建立实体类和表的映射关系
public class Customer implements Serializable {
    @Id//声明当前私有属性为主键
    @GeneratedValue(strategy = GenerationType.IDENTITY) //配置主键的生成策略
    @Column(name = "cust_id") //指定和表中cust_id字段的映射关系
    private Long custId;
    @Column(name = "cust_name") //指定和表中cust_name字段的映射关系
    private String custName;

    @Column(name = "cust_source")//指定和表中cust_source字段的映射关系
    private String custSource;

    @Column(name = "cust_industry")//指定和表中cust_industry字段的映射关系
    private String custIndustry;

    @Column(name = "cust_level")//指定和表中cust_level字段的映射关系
    private String custLevel;

    @Column(name = "cust_address")//指定和表中cust_address字段的映射关系
    private String custAddress;

    @Column(name = "cust_phone")//指定和表中cust_phone字段的映射关系
    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 + '\'' +
                '}';
    }
}

ii.编写一个符合springDataJpa的dao层接口

  • 只需要编写dao层接口,不需要编写dao层接口的实现类
  • dao层接口规范
    1.需要继承两个接口(JpaRepository,JpaSpecificationExecutor)
    2.需要提供响应的泛型
    findOne(id) :根据id查询
    save(customer):保存或者更新(依据:传递的实体类对象中,是否包含id属性)
    delete(id) :根据id删除
    findAll() : 查询全部
  1. CustomerDao.java
package cn.kt.dao;/*
 *Created by tao on 2020-05-04.
 */

import cn.kt.domain.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

/*
* 符合Springdata jpa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>
*       封住了基本的CRUD操作
*   JpaSpecificationExecutor<操作实体类的类型>
*       封装了复杂查询的操作(分页)
**/
public interface CustomerDao extends JpaRepository<Customer,Long>, JpaSpecificationExecutor<Customer> {
}
  1. CustomerTest.java(测试类)
package cn.kt.test;/*
 *Created by tao on 2020-05-04.
 */

import cn.kt.dao.CustomerDao;
import cn.kt.domain.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 java.util.List;

@RunWith(SpringJUnit4ClassRunner.class)  //声明单元测试
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class CustomerTest {
    @Autowired
    private CustomerDao customerDao;

    /*
     * 查询所有
     * */
    @Test
    public void testFindAll() {
        List<Customer> all = customerDao.findAll();
        for (Customer customer : all) {
            System.out.println(customer);
        }
    }

    /*
     * 根据id查询
     * */
    @Test
    public void testFindOne() {
        Customer one = customerDao.findOne(3l);
        System.out.println(one);
    }

    /**
     * 保存客户:调用save(obj)方法
     * 对于save方法的解释:如果执行此方法是对象中存在id属性,即为更新操作会先根据id查询,再更新
     * 如果执行此方法中对象中不存在id属性,即为保存操作
     */
    @Test
    public void testSave() {
        Customer c = new Customer();
        c.setCustName("妮可罗宾");
        customerDao.save(c);
    }

    @Test
    public void testUpdate() {
        /*不会覆盖的修改*/
        //根据id查询id为1的客户
        Customer customer = customerDao.findOne(10l);
        //修改客户
        customer.setCustIndustry("One Piece");
        customer.setCustAddress("海贼王");
        //更新
        customerDao.save(customer);

        /*覆盖的修改*/
        /*Customer customer = new Customer();
        customer.setCustId(10l);
        customer.setCustIndustry("One Piece");
        customerDao.save(customer);*/
    }

    /**
     * 根据id删除:调用delete(id)方法
     */
    @Test
    public void testDelete() {
        customerDao.delete(9l);
    }


}

springDataJpa的运行过程和原理剖析

1.通过JdkDynamicAopProxy的invoke方法创建了一个动态代理对象
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)
Spring的学习笔记(十六)——SpringDataJpa配置和相关的操作-左眼会陪右眼哭の博客

复杂查询

i.借助接口中的定义好的方法完成查询

Spring的学习笔记(十六)——SpringDataJpa配置和相关的操作-左眼会陪右眼哭の博客

findOne(id):根据id查询,立即加载
getOne(id):根据id查询,延迟加载
testCount():查询客户的总数量
testExists():判断id为4的客户是否存在

<br />    /*
    *测试统计查询,查询客户的总数量
    * */
    @Test
    public  void testCount(){
        long count = customerDao.count();
        System.out.println(count);
    }

    /*
     *测试判断id为4的客户是否存在
     * */
    @Test
    public  void testExists(){
        boolean exists = customerDao.exists(4l);
        System.out.println("id为4的客户是否存在:"+exists);
    }

    /*
    * findOne()
    *
    * 立即加载
    * @Transactional    保证getOne正常运行
    * getOne()
    * 延迟加载
    * 什么时候用,什么时候加载
    * */
    @Test
    @Transactional
    public void testGetOne(){
        Customer one = customerDao.getOne(2l);
        System.out.println(one);
    }

ii.jpql的查询方式

Spring的学习笔记(十六)——SpringDataJpa配置和相关的操作-左眼会陪右眼哭の博客

jpql : jpa query language (jpq查询语言)
特点:语法或关键字和sql语句类似
查询的是类和类中的属性

需要将JPQL语句配置到接口方法上
1.特有的查询:需要在dao接口上配置方法
2.在新添加的方法上,使用注解的形式配置jpql查询语句
3.注解 : @Query

iii.sql语句的查询

1.特有的查询:需要在dao接口上配置方法
2.在新添加的方法上,使用注解的形式配置sql查询语句
3.注解 : @Query
value :jpql语句 | sql语句
nativeQuery :false(使用jpql查询) | true(使用本地查询:sql查询)
是否使用本地查询

iiii.方法名称规则查询

  • 是对jpq1查询,更加深入的一层封装,
  • 我们只需要按照SpringDataJpa提供的方法名称规则定义方法,不需要再去配置jpql语句,完成查询
  • findBy开头:代表查询
    对象中属性的名称(首字母大写)
    含义:根据属性名称进行查询
  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"

复制查询测试

CustomerDao.java(接口)

package cn.kt.dao;/*
 *Created by tao on 2020-05-04.
 */

import cn.kt.domain.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;

import java.util.List;

/*
 * 符合Springdata jpa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>
 *       封住了基本的CRUD操作
 *   JpaSpecificationExecutor<操作实体类的类型>
 *       封装了复杂查询的操作(分页)
 **/
public interface CustomerDao extends JpaRepository<Customer, Long>, JpaSpecificationExecutor<Customer> {

    //@Query 使用jpql的方式查询。?1代表参数的占位符,其中1对应方法中的参数索引
    @Query(value = "from Customer where custName like %?1%")
    public Customer findCustomer(String custName);

    /*
     * 对于多个占位符
     * 默认情况下,占位符的位置要和参数的位置保持一致
     * 可以自己指定占位符的位置
     * 在   ?数字  来指定占位取值来源
     * */
    @Query(value = "from Customer where custName = ?2 and custId = ?1")
    public Customer findCustIdName(Long id, String name);

    //修改需要在使用 @Query 的同时,用 @Modifying 来将该操作标识为修改查询
    @Query(value = "update Customer set custName = ?1 where custId = ?2")
    @Modifying
    public void updateCustomer(String custName, Long custId);

    /**
     * sql查询
     * nativeQuery : 使用本地sql的方式查询
     */
    @Query(value = "select * from cst_customer", nativeQuery = true)
    public List<Customer> findSql();

    /**
     * sql查询:模糊查询
     * 注意:占位符
     */
    @Query(value = "select * from cst_customer where cust_name like %?1%", nativeQuery = true)
    public List<Customer> findSqlByCustName(String name);

    /*
     * 方法名的约定
     * findBy:查询
     *   对象名中的属性名(首字母大写):查询条件
     *   custName
     *   默认的情况下使用等于的方式进行查询
     *   特殊的查询方式
     * 在springDataJpa的运行阶段:
     *   会根据方法名称进行解析 findBy from xxx(实体类)
     *
     * 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"
     * */
    public Customer findByCustName(String custName);

    public List<Customer> findByCustNameLike(String custName);

    //使用用户名称模糊匹配和用户地址精准匹配
    public List<Customer> findByCustNameLikeAndCustAddress(String custName,String custAddress);


}

JpqlTest.java(测试代码)

package cn.kt.test;/*
 *Created by tao on 2020-05-04.
 */

import cn.kt.dao.CustomerDao;
import cn.kt.domain.Customer;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.annotation.Rollback;
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)  //声明单元测试
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class JpqlTest {
    @Autowired
    private CustomerDao customerDao;

    @Test
    public void TestFindCustomer() {
        Customer customer = customerDao.findCustomer("左眼");
        System.out.println(customer);
    }

    @Test
    public void TestFindCustIdName() {
        Customer customer = customerDao.findCustIdName(2l, "Nick");
        System.out.println(customer);
    }

    /*
    * 测试jpq1的更新操作
    * springDataJpa中 使用jpq1完成更新/删除操作
    * 注意:需要手动添加事务的支持
    * 默认会执行结束之后,回滚事务
        @Rollback :设置是否自动回滚
            false| true
    * */
    @Test
    @Transactional
    @Rollback
    public void TestUpdateCustomer() {
        customerDao.updateCustomer("红发香克斯", 8l);
    }

    @Test
    public void TestFindSql() {
        List<Customer> sql = customerDao.findSql();
        for (Customer customer : sql) {
            System.out.println(customer);
        }
    }

    @Test
    public void TestFindSqlByCustName() {
        List<Customer> customers = customerDao.findSqlByCustName("左眼");
        for (Customer customer : customers) {
            System.out.println(customer);
        }
    }

    /*测试命名规则的查询*/
    @Test
    public void TestFindByCustName() {
        Customer nick = customerDao.findByCustName("Nick");
        System.out.println(nick);
    }

    /*测试命名规则的模糊查询*/
    @Test
    public void TestFindByCustNameLike() {
        List<Customer> byCustNameLike = customerDao.findByCustNameLike("左眼%");
        for (Customer customer : byCustNameLike) {
            System.out.println(customer);
        }
    }/*测试命名规则的模糊查询*/
    @Test
    public void TestFindByCustNameLikeAndCustAddress() {
        List<Customer> customers = customerDao.findByCustNameLikeAndCustAddress("左眼%","江西赣州");
        for (Customer customer : customers) {
            System.out.println(customer);
        }
    }

}

以上有三种方法可以实现复杂的查询,这其中Jpql语句必须掌握,因为这种方法最具有面向对象的思想

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