spring data jpa 多对多 ManyToMany

环境搭建

源码地址：gitee：https://gitee.com/ytfs-dtx/JPA

导入依赖

<properties>

        <spring.version>5.2.5.RELEASE</spring.version>

        <hibernate.version>5.4.10.Final</hibernate.version>

        <slf4j.version>1.7.30</slf4j.version>

        <log4j.version>2.12.1</log4j.version>

        <druid.version>1.1.21</druid.version>

        <mysql.version>5.1.6</mysql.version>

    </properties>

    <dependencies>

        <!-- spring beg -->

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-aop</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

            <groupId>org.aspectj</groupId>

            <artifactId>aspectjweaver</artifactId>

            <version>1.9.5</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-test</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>

        <!-- hibernate beg -->

        <dependency>

            <groupId>org.hibernate</groupId>

            <artifactId>hibernate-entitymanager</artifactId>

            <version>${hibernate.version}</version>

        </dependency>

        <dependency>

            <groupId>org.hibernate</groupId>

            <artifactId>hibernate-core</artifactId>

            <version>${hibernate.version}</version>

        </dependency>

        <dependency>

            <groupId>org.hibernate.validator</groupId>

            <artifactId>hibernate-validator</artifactId>

            <version>6.1.2.Final</version>

            <exclusions>

                <exclusion>

                    <artifactId>classmate</artifactId>

                    <groupId>com.fasterxml</groupId>

                </exclusion>

            </exclusions>

        </dependency>

        <!-- hibernate end -->

        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

            <version>${mysql.version}</version>

        </dependency>

        <dependency>

            <groupId>com.alibaba</groupId>

            <artifactId>druid</artifactId>

            <version>${druid.version}</version>

        </dependency>

        <!-- spring data jpa 的坐标 -->

        <dependency>

            <groupId>org.springframework.data</groupId>

            <artifactId>spring-data-jpa</artifactId>

            <version>2.2.6.RELEASE</version>

            <exclusions>

                <exclusion>

                    <artifactId>slf4j-api</artifactId>

                    <groupId>org.slf4j</groupId>

                </exclusion>

            </exclusions>

        </dependency>

        <!--  el beg 使用spring data jpa 必须引入 -->

        <dependency>

            <groupId>javax.el</groupId>

            <artifactId>javax.el-api</artifactId>

            <version>3.0.0</version>

        </dependency>

        <dependency>

            <groupId>org.glassfish</groupId>

            <artifactId>javax.el</artifactId>

            <version>3.0.0</version>

        </dependency>

        <dependency>

            <groupId>org.slf4j</groupId>

            <artifactId>slf4j-api</artifactId>

            <version>${slf4j.version}</version>

        </dependency>

        <dependency>

            <groupId>org.apache.logging.log4j</groupId>

            <artifactId>log4j-api</artifactId>

            <version>${log4j.version}</version>

        </dependency>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>4.12</version>

        </dependency>

    </dependencies>

创建配置文件

<?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">

    <!-- 配置实体类管理工厂 -->

    <bean id="entityManagerFactoryBean" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">

        <property name="dataSource" ref="dataSource"/>

        <!-- 配置实体类的扫描 -->

        <property name="packagesToScan" value="xyz.ytfs.entity"/>

        <!-- 配置jpa的提供方 -->

        <property name="persistenceProvider">

            <bean class="org.hibernate.jpa.HibernatePersistenceProvider"/>

        </property>

        <!-- 配置提供方的适配器 -->

        <property name="jpaVendorAdapter">

            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">

                <!-- 数据库的类型 -->

                <property name="database" value="MYSQL"/>

                <!-- 不自动创表 -->

                <property name="generateDdl" value="false"/>

                <!-- 控制台打印sql语句 -->

                <property name="showSql" value="true"/>

                <property name="databasePlatform" value="org.hibernate.dialect.MySQL55Dialect"/>

            </bean>

        </property>

        <!--  jpa的方言：高级特性 -->

        <property name="jpaDialect">

            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"/>

        </property>

        <property name="jpaProperties">

            <props>

                <prop key="hibernate.hbm2ddl.auto">update</prop>

            </props>

        </property>

    </bean>

    <!-- 配置JPA的事务管理器 -->

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">

        <property name="entityManagerFactory" ref="entityManagerFactoryBean"/>

    </bean>

    <!-- JPA -->

    <jpa:repositories base-package="xyz.ytfs.dao" transaction-manager-ref="transactionManager"

                      entity-manager-factory-ref="entityManagerFactoryBean"/>

    <!-- 配置数据源 -->

    <context:property-placeholder location="classpath:jdbcConfig.properties"/>

    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">

        <property name="driverClassName" value="${jdbc.driver}"/>

        <property name="url" value="${jdbc.url}"/>

        <property name="username" value="${jdbc.username}"/>

        <property name="password" value="${jdbc.password}"/>

    </bean>

</beans>

创建实体类

注解说明

@ManyToMany

    作用：用于映射多对多关系

    属性：

        cascade：配置级联操作。

        fetch：配置是否采用延迟加载。

        targetEntity：配置目标的实体类。映射多对多的时候不用写。

@JoinTable

    作用：针对中间表的配置

    属性：

        nam：配置中间表的名称

        joinColumns：中间表的外键字段关联当前实体类所对应表的主键字段

        inverseJoinColumn：中间表的外键字段关联对方表的主键字段

@JoinColumn

    作用：用于定义主键字段和外键字段的对应关系。

    属性：

        name：指定外键字段的名称

        referencedColumnName：指定引用主表的主键字段名称

        unique：是否唯一。默认值不唯一

        nullable：是否允许为空。默认值允许。

        insertable：是否允许插入。默认值允许。

        updatable：是否允许更新。默认值允许。

        columnDefinition：列的定义信息。

User

package xyz.ytfs.entity;

import javax.persistence.*;

import java.util.HashSet;

import java.util.Set;

/**

 * @author by ytfs

 * @Classname User

 * @Description TODO(用户类)

 * @Date 2020/5/9 23:47

 */

@Entity

@Table(name = "sys_user")

public class User {

    @Id

    @GeneratedValue(strategy = GenerationType.IDENTITY)

    @Column(name = "user_id")

    private Long userId;

    @Column(name = "user_name")

    private String userName;

    /**

     * 配置用户到角色的多对多关系

     * 配置多对多的映射关系

     * 1.声明表关系的配置

     *

     * @ManyToMany(targetEntity = Role.class)  //多对多

     * targetEntity：代表对方的实体类字节码

     * 2.配置中间表（包含两个外键）

     * @JoinTable name : 中间表的名称

     * joinColumns：配置当前对象在中间表的外键

     * @JoinColumn的数组 name：外键名

     * referencedColumnName：参照的主表的主键名

     * inverseJoinColumns：配置对方对象在中间表的外键

     */

    @ManyToMany(targetEntity = Role.class, cascade = CascadeType.ALL)

    @JoinTable(name = "sys_user_role",

            //joinColumns,当前对象在中间表中的外键

            joinColumns = {@JoinColumn(name = "sys_user_id", referencedColumnName = "user_id")},

            //inverseJoinColumns，对方对象在中间表的外键

            inverseJoinColumns = {@JoinColumn(name = "sys_role_id", referencedColumnName = "role_id")})

    private Set<Role> roles = new HashSet<>();

    public Long getUserId() {

        return userId;

    }

    public void setUserId(Long userId) {

        this.userId = userId;

    }

    public String getUserName() {

        return userName;

    }

    public void setUserName(String userName) {

        this.userName = userName;

    }

    public Set<Role> getRoles() {

        return roles;

    }

    public void setRoles(Set<Role> roles) {

        this.roles = roles;

    }

    @Override

    public String toString() {

        return "User{" +

                "userId=" + userId +

                ", userName='" + userName + '\'' +

                ", roles=" + roles +

                '}';

    }

}

Role

package xyz.ytfs.entity;

import javax.persistence.*;

import java.util.HashSet;

import java.util.Set;

/**

 * @author by ytfs

 * @Classname Role

 * @Description TODO(用户对应的类型)

 * @Date 2020/5/9 23:47

 */

@Entity

@Table(name = "sys_role")

public class Role {

    @Id

    @GeneratedValue(strategy = GenerationType.IDENTITY)

    @Column(name = "role_id")

    private Long roleId;

    @Column(name = "role_name")

    private String roleName;

    /**

     * 配置用户到角色的多对多关系

     *      配置多对多的映射关系

     *          1.声明表关系的配置

     *              @ManyToMany(targetEntity = User.class)  //多对多

     *                  targetEntity：代表对方的实体类字节码

     *          2.配置中间表（包含两个外键）

     *                @JoinTable

     *                  name : 中间表的名称

     *                  joinColumns：配置当前对象在中间表的外键

     *                      @JoinColumn的数组

     *                          name：外键名

     *                          referencedColumnName：参照的主表的主键名

     *                  inverseJoinColumns：配置对方对象在中间表的外键

     */

     /*  @ManyToMany(targetEntity = User.class)

        @JoinTable(name = "sys_user_role",

            //joinColumns,当前对象在中间表中的外键

            joinColumns = {@JoinColumn(name = "sys_role_id", referencedColumnName = "role_id")},

            //inverseJoinColumns，对方对象在中间表的外键

            inverseJoinColumns = {@JoinColumn(name = "sys_user_id", referencedColumnName = "user_id")})*/

    @ManyToMany(mappedBy = "roles")

    private Set<User> users = new HashSet<>();

    public Set<User> getUsers() {

        return users;

    }

    public void setUsers(Set<User> users) {

        this.users = users;

    }

    public Long getRoleId() {

        return roleId;

    }

    public void setRoleId(Long roleId) {

        this.roleId = roleId;

    }

    public String getRoleName() {

        return roleName;

    }

    public void setRoleName(String roleName) {

        this.roleName = roleName;

    }

    @Override

    public String toString() {

        return "Role{" +

                "roleId=" + roleId +

                ", roleName='" + roleName + '\'' +

                ", users=" + users +

                '}';

    }

}

创建数据访问层的接口

IUserDao

package xyz.ytfs.dao;

import org.springframework.data.jpa.repository.JpaRepository;

import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

import xyz.ytfs.entity.User;

/**

 * @author by ytfs

 * @Classname UserDao

 * @Description TODO(用户的数据访问层接口)

 * @Date 2020/5/10 0:05

 */

public interface IUserDao extends JpaRepository<User, Long>, JpaSpecificationExecutor<User> {

}

IRoleDao

package xyz.ytfs.dao;

import org.springframework.data.jpa.repository.JpaRepository;

import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

import xyz.ytfs.entity.Role;

/**

 * @author by ytfs

 * @Classname IRoleDao

 * @Description TODO(用户对应的职位数据访问层)

 * @Date 2020/5/10 0:07

 */

public interface IRoleDao extends JpaRepository<Role, Long>, JpaSpecificationExecutor<Role> {

}

测试类

package xyz.ytfs.test;

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 xyz.ytfs.dao.IRoleDao;

import xyz.ytfs.dao.IUserDao;

import xyz.ytfs.entity.Role;

import xyz.ytfs.entity.User;

import javax.transaction.Transactional;

import java.util.HashSet;

/**

 * @author by ytfs

 * @Classname JpaManyToManyTest

 * @Description TODO(多对多的测试类)

 * @Date 2020/5/10 0:08

 */

@RunWith(SpringJUnit4ClassRunner.class)

@ContextConfiguration(locations = "classpath:applicationContext.xml")

public class JpaManyToManyTest {

    @Autowired

    private IRoleDao roleDao;

    @Autowired

    private IUserDao userDao;

    /**

     * 保存一个用户，保存一个角色

     * <p>

     * 多对多放弃维护权：被动的一方（这里就是被选择的一方Role）放弃

     */

    @Test

    @Transactional

    @Rollback(false)

    public void testSave() {

        User user = new User();

        user.setUserName("雨听风说");

        Role role = new Role();

        role.setRoleName("程序猿");

         /*

         表达多对多的关系，双方都表达的时候必须有一方放弃维护中间表，不然会抛出异常

          */

        role.getUsers().add(user);

        user.getRoles().add(role);

        this.userDao.save(user);

        this.roleDao.save(role);

    }

    //测试级联添加（保存一个用户的同时保存用户的关联角色）

    @Test

    @Transactional

    @Rollback(false)

    public void testCasacdeSave() {

        User user = new User();

        user.setUserName("雨听风说");

        Role role = new Role();

        role.setRoleName("程序猿");

        /*

         表达多对多的关系

          */

        role.getUsers().add(user);

        user.getRoles().add(role);

        //级联操作，在保存用户的同时保存用户的类型

        this.userDao.save(user);

    }

    /**

     * 级联删除，删除id为1的客户

     */

    @Test

    @Transactional

    @Rollback(false)

    public void testDeleteCasaced() {

        //查询id为1的用户

        User user = this.userDao.getOne(1L);

        //删除id为1的用户，级联删除用户对应的类型

        this.userDao.delete(user);

    }

}