SpringDataJPA 多对多的查询

 主要的结构目录：

创建Role.java

package cn.itcast.domain;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@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;

    /**
     *配置多对多
     */
    @ManyToMany(targetEntity = User.class)//配置多表关系
    @JoinTable(name= "sys_user_role"
            //joinColumns,当前对象在中间表的外键
            ,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")})
    private Set<User> users=new HashSet<User>();

    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;
    }

    public Set<User> getUsers() {
        return users;
    }

    public void setUsers(Set<User> users) {
        this.users = users;
    }
}

　　主要的User.java

package cn.itcast.domain;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@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;
    @Column(name = "age")
    private Integer age;

    /**
     *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)
     *       targetEntity:代表对方的实体类字节码
     *     2、配置中间表（包含两个外键）
     *       name：中间表的名称
     *       joinColumns,当前对象在中间表的外键
     *          name：外键名
     *          referencedColumnName：参照的主表的主键名
     *       inverseJoinColumns，对方对象在中间表的外键
     *          name：外键名
     *          referencedColumnName：
     */
    @ManyToMany(targetEntity = Role.class,cascade = CascadeType.ALL)
    @JoinTable(name= "sys_user_role"
            //joinColumns,当前对象在中间表的外键
            ,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<Role>();

    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 Integer getAge() {
        return age;
    }

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

    public Set<Role> getRoles() {
        return roles;
    }

    public void setRoles(Set<Role> roles) {
        this.roles = roles;
    }
}

　　主要的RoleDao.java

public interface RoleDao extends JpaRepository<Role,Long>,JpaSpecificationExecutor<Role> {
}

　　主要的UserDao.java

public interface UserDao extends JpaRepository<User,Long>,JpaSpecificationExecutor<User> {
}

　　在配置applicationContext.xml中

<?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"
       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">

    <!--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的供应商适配器 -->
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <!--配置是否自动创建数据库表 -->
                <property name="generateDdl" value="false" />
                <!--指定数据库类型 -->
                <property name="database" value="MYSQL" />
                <!--数据库方言：支持的特有语法 -->
                <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
                <!--是否显示sql -->
                <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>

        <!--注入jpa的配置信息
            加载jpa的基本配置信息和jpa实现方式（hibernate）的配置信息
            hibernate.hbm2ddl.auto : 自动创建数据库表
                create ： 每次都会重新创建数据库表
                update：有表不会重新创建，没有表会重新创建表
        -->
        <property name="jpaProperties" >
            <props>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
            </props>
        </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>
        <property name="password" value="root"></property>
        <property name="jdbcUrl" value="jdbc:mysql:///jpa" ></property>
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
    </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>

    <!-- 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.itcast.service.*.*(..))" />
        <aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" />
    </aop:config>

    <!--5.声明式事务 -->

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

　　

    保存一个用户，保存一个角色

    主要的applicationContext.xml中

     <property name="jpaProperties" >
            <props>
                <prop key="hibernate.hbm2ddl.auto">create</prop>
            </props>
        </property>

    @Test
    @Transactional
    @Rollback(false)
    public  void  testAdd(){
        User user = new User();
        user.setUserName("小李");

        Role role = new Role();
        role.setRoleName("java程序员");

        user.getRoles().add(role);

        userDao.save(user);
        roleDao.save(role);

    }

　　测试中

//测试级联添加
    @Test
    @Transactional
    @Rollback(false)
    public  void  testCadeAdd(){
        User user = new User();
        user.setUserName("小李");

        Role role = new Role();
        role.setRoleName("java程序员");

        user.getRoles().add(role);

        userDao.save(user);
        //roleDao.save(role);

    }

    //测试级联删除
    @Test
    @Transactional
    @Rollback(false)
    public  void  testCadeRemove(){
        //查询1号用户
        User user = userDao.findOne(1l);
        //删除1号用户
        userDao.delete(user);
    }

　　在测试中主要spring配置中的问题，主要是配置中不能出问题。在这些中主要调用的是接口中继承的两个类，所以前面也介绍了继承的两个类中的方法