Spring Data JPA基本增删改查和JPQL查询（含完整代码和视频连接)

• 2021 年 1 月 29 日
• 笔记

• 问题：SpringDataJPA怎么使用？

一、考察目标

• 主要考核SpringDataJPA的用法

二、题目分析

spring data jpa 的使用步骤（下面有具体实现细节）

• 1.创建maven工程并导入依赖

• 2.添加配置

• 3.实体类添加注解

• 4.编写dao接口

• 5.编写测试类

三、应用场景

• spring data jpa 是针对jpa规范中具体实现的在封装，hibernate框架就是jpa规范的具体实现。

四、总结

主要考察的是:

• 1.spring data jpa 的环境搭建
• 2.spring data jpa 的常用注解
• 3.spring data jpa 的dao编写要求

其中spring data jpa 的使用步骤

首先看一下项目的结构

点击即可进入视频学习网站

1.导入依赖

• 在pom.xml文件导入以下依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="//maven.apache.org/POM/4.0.0"
         xmlns:xsi="//www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="//maven.apache.org/POM/4.0.0 //maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.itcast</groupId>
    <artifactId>jpa-day2</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>5.1.6</mysql.version>
    </properties>

    <dependencies>
        <!--junit单元测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</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>

        <!-- spring对orm框架的支持包-->
        <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>

        <!-- spring data jpa 的坐标 -->
        <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>${spring.version}</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.配置

• 在applicationContext.xml文件中配置上以下信息

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="//www.springframework.org/schema/beans"
       xmlns:xsi="//www.w3.org/2001/XMLSchema-instance" xmlns:lang="//www.springframework.org/schema/lang"
       xmlns:jpa="//www.springframework.org/schema/data/jpa"
       xmlns:context="//www.springframework.org/schema/context"
       xsi:schemaLocation="//www.springframework.org/schema/beans //www.springframework.org/schema/beans/spring-beans.xsd
       //www.springframework.org/schema/lang //www.springframework.org/schema/lang/spring-lang.xsd
       //www.springframework.org/schema/data/jpa //www.springframework.org/schema/data/jpa/spring-jpa.xsd
       //www.springframework.org/schema/context //www.springframework.org/schema/context/spring-context.xsd">

    <!-- spring 和 spring data jpa 的配置-->

    <!-- 1.创建entityManagerFactory对象交给spring容器管理-->
    <bean id ="entityManagerFactoty" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <!-- 配置的扫描的包（实体类所在的包）-->
        <property name="packagesToScan" value="cn.itcast.domain"/>
        <!-- jpa的实现厂家 -->
        <property name="persistenceProvider">
            <bean class="org.hibernate.jpa.HibernatePersistenceProvider"/>
        </property>

        <!-- jpa的供应适配器 -->
        <property name="jpaVendorAdapter">
            <bean class = "org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="generateDdl" value="false" />
                <!-- 指定数据库类型 -->
                <property name="database" value="MYSQL" />
                <!--数据库方言: 支持的特有语法-->
                <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect"/>
                <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>

    <!--2.创建数据库连接池-->
    <bean id = "dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="user" value= "root"/>
        <property name="password" value = "root"/>
        <property name="jdbcUrl" value="jdbc:mysql:///jpa"/>
        <property name="driverClass" value="com.mysql.jdbc.Driver"/>
    </bean>

    <!-- 3.整合 spring datajpa -->
    <jpa:repositories base-package="cn.itcast.dao" transaction-manager-ref="transactionManager"
                      entity-manager-factory-ref="entityManagerFactoty"></jpa:repositories>

    <!--4.配置事务管理器-->
    <bean id = "transactionManager" class = "org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref = "entityManagerFactoty"></property>
    </bean>

    <!-- 5。声明式事务 -->

    <!-- 6. 配置包扫描 -->
    <context:component-scan base-package="cn.itcast"></context:component-scan>
</beans>

3.实体类添加注解

package cn.itcast.domain;

import javax.persistence.*;

/**
 * 客户的实体类
 *      配置映射关系
 *              1.实体类和表的映射关系
 *              2.实体类中属性和表中字段的映射关系
 * @Entity：声明实体类
 * @Table：配置实体类和表的映射关系
 *      name：配置数据库表的名称
 */

@Entity
@Table(name = "cst_customer")
public class Customer {

    /**
     * @Id：声明主键的配置
     * @GeneratedValue：配置主键的生成策略
     *      strategy
     *          GenerationType.IDENTITY：自增，mysql
     *              *底层数据库必须支持自动增长（底层数据库支持的自动增长方式，对id自增）
     *          GenerationType.SEQUENCE：序列，oracle
     *              *底层数据库必须支持序列
     *          GenerationType.TABLE ：jpa提供的一种机制，通过一张数据库表的形式帮助我们完成主键自增
     *          GenerationType.AUTO ：有程序自动的帮助我们选择主键生成策略
     * @Column:配置属性和字段的映射关系
     *      name：数据库表中字段的名称
     */

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "cust_id")
    private long custId;//客户的主键

    @Column(name = "cust_name")
    private String custName;//客户名称

    @Column(name = "cust_source")
    private String custSource;//客户来源

    @Column(name = "cust_level")
    private String custLevel;//客户级别

    @Column(name = "cust_industry")
    private String custIndustry;//客户所属行业

    @Column(name = "cust_phone")
    private String custPhone;//客户的联系方式

    @Column(name = "cust_address")
    private String custAddress;//客户地址

    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 getCustLevel() {
        return custLevel;
    }

    public void setCustLevel(String custLevel) {
        this.custLevel = custLevel;
    }

    public String getCustIndustry() {
        return custIndustry;
    }

    public void setCustIndustry(String custIndustry) {
        this.custIndustry = custIndustry;
    }

    public String getCustPhone() {
        return custPhone;
    }

    public void setCustPhone(String custPhone) {
        this.custPhone = custPhone;
    }

    public String getCustAddress() {
        return custAddress;
    }

    public void setCustAddress(String custAddress) {
        this.custAddress = custAddress;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "custId=" + custId +
                ", custName='" + custName + '\'' +
                ", custSource='" + custSource + '\'' +
                ", custLevel='" + custLevel + '\'' +
                ", custIndustry='" + custIndustry + '\'' +
                ", custPhone='" + custPhone + '\'' +
                ", custAddress='" + custAddress + '\'' +
                '}';
    }
}

4.编写Dao接口

package cn.itcast.dao;

import cn.itcast.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SpringDataJpa的dao层接口规范
 *      JpaRepository<操作的实体类类型，实体类中主键的类型>
 *          *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> {

    /**
     * 案列：根据客户名称查询客户
     *      使用jpql的形式查询
     *  jpql：from Customer where custName = ?
     *
     *  配置jpql语句，使用的@Query注解
     */
    @Query(value = "from Customer where custName = ?")
    public Customer findJpql(String custName);

    /**
     * 案列：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")
    public Customer findCustNameAndId(Long id, String name);

    /**
     * 使用jpql完成更新操作
     *      案例：根据id更新客户的名称
     *          更新4好客户的名称，将名称改为“黑马程序员”
     *  sql  :update cst_customer set cust_name = ? where cust_id = ?
     *  jpql :update Customer set custName = ? where custId = ?
     *
     * @Query:代表的时进行查询
     *      *声明次方法时用来进行更新操作
     * @Modifying
     *      *当前执行的是一个更新操作
     */
    @Query(value = "update Customer set custName = ?2 where custId = ?1")
    @Modifying
    public void updateCustomer(long custId, String custName);


    /**
     *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
     * @return
     */
//    @Query(value = "select * from cst_customer", nativeQuery = true)
    @Query(value = "select * from cst_customer where cust_name like ?1", nativeQuery = true)
    public List<Object []> findSql(String name);

    /**
     * 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（根据属性名称精选完成匹配的查询=
     *      2.findBy + 属性名称 + ”查询方式（Like | isnull)"
     *              findByCustNameLike
     *      3.多条件查询
     *          findBy + 属性名称 + “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);

    //使用客户名称模糊匹配和客户所属行业精准匹配的查询
    public Customer findByCustNameLikeAndCustIndustry(String custName, String custIndustry);
}

5.测试用例

package cn.itcast.test;

import cn.itcast.dao.CustomerDao;
import cn.itcast.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 org.springframework.transaction.annotation.Transactional;

import java.util.List;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")//指定spring容器的配置信息
public class CustomerDaoTest {
    @Autowired
    private CustomerDao customerDao;

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

    /**
     * sava : 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("黑马程序员");
        customer.setCustLevel("vip");
        customer.setCustIndustry("it教育");
        customerDao.save(customer);
    }

    @Test
    public void testUpdate() {
        Customer customer = new Customer();
        customer.setCustId(4l);
        customer.setCustName("黑马程序员很厉害");
        customerDao.save(customer);
    }

    @Test
    public void testDelete() {
        customerDao.delete(3L);
    }

    @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
     *          cont：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.可以查询一下id为4的客户
     *          如果值为空，代表不存在，如果部位空，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
     *      *返回的时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);
    }
}

JPQL测试用例

package cn.itcast.test;

import cn.itcast.dao.CustomerDao;
import cn.itcast.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.Arrays;
import java.util.List;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")//指定spring容器的配置信息
public class JpqlTest {
    @Autowired
    private CustomerDao customerDao;

    @Test
    public void testFindJPQL() {
        Customer customer = customerDao.findJpql("传智播客");
        System.out.println(customer);
    }

    @Test
    public void testFindCustNameAndId() {
        Customer customer = customerDao.findCustNameAndId(1L, "传智播客");
        System.out.println(customer);
    }

    /**
     * 测试jpql的更新操作
     * *springDataJpa中使用jpql完成 更新/删除操作
     *      *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//添加事务的支持
    @Rollback(value = false)
    public void testUpdateCustomer() {
        customerDao.updateCustomer(4L, "黑马程序员");
    }

    //测试sql查询
    @Test
    public void testFindSql() {
        List<Object[]> list = customerDao.findSql("传智播客%");
        for (Object[] obj : list) {
            System.out.println(Arrays.toString(obj));
        }
    }

    //测试方法命名规则的查询
    @Test
    public void testNaming() {
        Customer customer = customerDao.findByCustName("传智播客");
        System.out.println(customer);
    }

    //测试方法命名规则的查询
    @Test
    public void testFindByCustNameLike() {
        List<Customer> list = customerDao.findByCustNameLike("传智播客%");
        for (Customer customer : list) {
            System.out.println(customer);
        }
    }

    //测试方法命名规则的查询
    @Test
    public void testFindByCustNameLikeAndCustIndustry() {
        Customer customer = customerDao.findByCustNameLikeAndCustIndustry("传智播客%", "it教育");
        System.out.println(customer);
    }
}

如果觉得有收获，不妨花个几秒钟点个赞，欢迎关注我的公众号玩编程地码农，目前专注于写java相关、数据结构与算法和计算机基础等。