JPA--SpringDataJPA一对多关联、级联操作

短命女 2021-08-13 20:54 492阅读 0赞

### 实体类 ###

package pers.zhang.entity;
    
    /** * @author zhang * @date 2019/12/15 - 22:10 */
    
    import javax.persistence.*;
    import java.util.HashSet;
    import java.util.Set;
    
    /** * 1.实体类和表的映射关系 * @Entity * @Table * 2.类中属性和表中字段的映射关系 * @Id * @GeneratedValue * @Colum */
    
    @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 { 
    
        @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;
    
        //配置客户和联系人之间的关系（一对多）
        /* 1.声明关系： 配置一对多关系：@OneToMany：targetEntity（对方对象的字节码） 2.配置外键（中间表） name:外键字段的名称 referencedColumnName：参照的主表的主键字段名称 在客户实体类上（一的一方）添加了外键的配置，所以对于客户而言，也具备了维护外键的作用 实际情况下，只需要一方维护关系即可 mappedBy表示：放弃外键维护，由对方维护，取值为对方配置关系的属性名称 级联：cascade CascadeType.ALL:所有 MERGE:更新 PERSIST：保存 REMOVE：删除 */
    // @OneToMany(targetEntity = LinkMan.class)
    // @JoinColumn(name = "lkm_cust_id", referencedColumnName = "cust_id")
        @OneToMany(mappedBy = "customer", cascade = CascadeType.ALL)
        private Set<LinkMan> linkMans = new HashSet<>();
    
        public Set<LinkMan> getLinkMans() { 
            return linkMans;
        }
    
        public void setLinkMans(Set<LinkMan> linkMans) { 
            this.linkMans = linkMans;
        }
    
        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 + '\'' +
                    '}';
        }
    }

package pers.zhang.entity;
    
    import org.springframework.test.context.ContextConfiguration;
    import sun.awt.SunHints;
    
    import javax.naming.Name;
    import javax.persistence.*;
    
    /** * @author zhang * @date 2019/12/17 - 20:23 */
    @Entity
    @Table(name = "cst_linkman")
    public class LinkMan { 
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "lkm_id")
        private Long lkmId;//联系人编号
    
        @Column(name = "lkm_name")
        private String lkmName;//联系人姓名
    
        @Column(name = "lkm_gender")
        private String lkmGender;//联系人性别
    
        @Column(name = "lkm_phone")
        private String lkmPhone;//联系人办公电话
    
        @Column(name = "lkm_mobile")
        private String lkmMobile;//联系人手机
    
        @Column(name = "lkm_email")
        private String lkmEmail;//联系人E-mail
    
        @Column(name = "lkm_position")
        private String lkmPosition;//联系人地址
    
        @Column(name = "lkm_memo")
        private String lkmMemo;//联系人备注
    
        //配置联系人到客户的多对一关系
        /* @ManyToOne：配置多对一关系 targetEntity：对方的实体类额字节码 @JoinColumn：配置外键（中间表） name:外键字段名 referencedColumnName：外键引用的主表主键字段名 */
        @ManyToOne(targetEntity = Customer.class)
        @JoinColumn(name = "lkm_cust_id", referencedColumnName = "cust_id")
        private Customer customer;
    
        public Customer getCustomer() { 
            return customer;
        }
    
        public void setCustomer(Customer customer) { 
            this.customer = customer;
        }
    
        public Long getLkmId() { 
            return lkmId;
        }
    
        public void setLkmId(Long lkmId) { 
            this.lkmId = lkmId;
        }
    
        public String getLkmName() { 
            return lkmName;
        }
    
        public void setLkmName(String lkmName) { 
            this.lkmName = lkmName;
        }
    
        public String getLkmGender() { 
            return lkmGender;
        }
    
        public void setLkmGender(String lkmGender) { 
            this.lkmGender = lkmGender;
        }
    
        public String getLkmPhone() { 
            return lkmPhone;
        }
    
        public void setLkmPhone(String lkmPhone) { 
            this.lkmPhone = lkmPhone;
        }
    
        public String getLkmMobile() { 
            return lkmMobile;
        }
    
        public void setLkmMobile(String lkmMobile) { 
            this.lkmMobile = lkmMobile;
        }
    
        public String getLkmEmail() { 
            return lkmEmail;
        }
    
        public void setLkmEmail(String lkmEmail) { 
            this.lkmEmail = lkmEmail;
        }
    
        public String getLkmPosition() { 
            return lkmPosition;
        }
    
        public void setLkmPosition(String lkmPosition) { 
            this.lkmPosition = lkmPosition;
        }
    
        public String getLkmMemo() { 
            return lkmMemo;
        }
    
        public void setLkmMemo(String lkmMemo) { 
            this.lkmMemo = lkmMemo;
        }
    }

### Dao接口 ###

package pers.zhang.dao;
    
    import org.springframework.data.jpa.repository.JpaRepository;
    import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
    import pers.zhang.entity.Customer;
    
    /** * @author zhang * @date 2019/12/17 - 20:22 */
    public interface CustomerDao extends JpaRepository<Customer, Long>, JpaSpecificationExecutor<Customer> { 
    }

package pers.zhang.dao;
    
    import org.springframework.data.jpa.repository.JpaRepository;
    import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
    import pers.zhang.entity.LinkMan;
    
    /** * @author zhang * @date 2019/12/17 - 20:36 */
    public interface LinkManDao extends JpaRepository<LinkMan, Long>, JpaSpecificationExecutor<LinkMan> { 
    }

### 测试类 ###

package pers.zhang;
    
    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 pers.zhang.dao.CustomerDao;
    import pers.zhang.dao.LinkManDao;
    import pers.zhang.entity.Customer;
    import pers.zhang.entity.LinkMan;
    
    /** * @author zhang * @date 2019/12/17 - 20:23 */
    @RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(locations = "classpath:applicationContext.xml")
    public class myTest { 
    
        @Autowired
        private CustomerDao customerDao;
    
        @Autowired
        private LinkManDao linkManDao;
    
    
        /* 保存一个客户，一个联系人 */
        @Test
        @Transactional
        @Rollback(false)
        public void testAdd(){ 
            Customer customer = new Customer();
            customer.setCustName("百度百度");
    
            LinkMan linkMan = new LinkMan();
            linkMan.setLkmName("小李");
    
            //客户对外键进行维护
            customer.getLinkMans().add(linkMan);
    
            linkManDao.save(linkMan);
            customerDao.save(customer);
    
            /* Hibernate: insert into cst_linkman (lkm_cust_id, lkm_email, lkm_gender, lkm_memo, lkm_mobile, lkm_name, lkm_phone, lkm_position) values (?, ?, ?, ?, ?, ?, ?, ?) Hibernate: insert into cst_customer (cust_address, cust_industry, cust_level, cust_name, cust_phone, cust_source) values (?, ?, ?, ?, ?, ?) Hibernate: update cst_linkman set lkm_cust_id=? where lkm_id=? */
    
    
        }
    
    
    
        @Test
        @Transactional
        @Rollback(false)
        public void testAdd2(){ 
            Customer customer = new Customer();
            customer.setCustName("育碧");
    
            LinkMan linkMan = new LinkMan();
            linkMan.setLkmName("歌玲");
    
            //联系人维护关系
            linkMan.setCustomer(customer);
    
            linkManDao.save(linkMan);
            customerDao.save(customer);
    
            /* Hibernate: insert into cst_linkman (lkm_cust_id, lkm_email, lkm_gender, lkm_memo, lkm_mobile, lkm_name, lkm_phone, lkm_position) values (?, ?, ?, ?, ?, ?, ?, ?) Hibernate: insert into cst_customer (cust_address, cust_industry, cust_level, cust_name, cust_phone, cust_source) values (?, ?, ?, ?, ?, ?) Hibernate: update cst_linkman set lkm_cust_id=?, lkm_email=?, lkm_gender=?, lkm_memo=?, lkm_mobile=?, lkm_name=?, lkm_phone=?, lkm_position=? where lkm_id=? */
        }
    
    
        /* 级联：操作一个对象的同时操作它的关联对象 级联操作： 1. 需要区分操作主体 2. 需要在操作主体的实体类上，添加级联属性（需要添加到多表映射关系的注解上） 3. cascade（配置级联） 级联添加： 示例：保存一个客户的同时保存联系人 级联删除： 示例：删除一个客户的同时删除对应的所有联系人 */
    
    
        /* 级联添加：保存一个客户的同时保存联系人 */
        @Test
        @Transactional
        @Rollback(false)
        public void testCascadeAdd(){ 
            Customer customer = new Customer();
            customer.setCustName("任天堂");
    
            LinkMan linkMan1 = new LinkMan();
            linkMan1.setLkmName("AAA");
            LinkMan linkMan2 = new LinkMan();
            linkMan2.setLkmName("BBB");
    
            //联系人维护关系
            linkMan1.setCustomer(customer);
            linkMan2.setCustomer(customer);
            customer.getLinkMans().add(linkMan1);
            customer.getLinkMans().add(linkMan2);
    
            customerDao.save(customer);
    
            /* Hibernate: insert into cst_customer (cust_address, cust_industry, cust_level, cust_name, cust_phone, cust_source) values (?, ?, ?, ?, ?, ?) Hibernate: insert into cst_linkman (lkm_cust_id, lkm_email, lkm_gender, lkm_memo, lkm_mobile, lkm_name, lkm_phone, lkm_position) values (?, ?, ?, ?, ?, ?, ?, ?) Hibernate: insert into cst_linkman (lkm_cust_id, lkm_email, lkm_gender, lkm_memo, lkm_mobile, lkm_name, lkm_phone, lkm_position) values (?, ?, ?, ?, ?, ?, ?, ?) */
    
        }
    
        /* 删除主表数据： 1. 有从表数据： 1.1：在默认情况下，它会把外键字段置为null，然后删除主表数据。如果在数据库的表结构上，外键字段有非空约束，默认情况就会报错。 1.2：如果配置了放弃维护关联关系，则不能删除（与外键字段是否允许为null没有关系），因为在删除时，它根本不会去更新从表的外键字段。 1.3：如果还想删除，使用级联删除引用 2. 没有从表数据： 随便删~~~ */
    
        /* 级联删除:删除客户的同时，删除对应的所有联系人 */
        @Test
        @Transactional
        @Rollback(false)
        public void testCascadeDelete(){ 
            Customer customer = customerDao.findOne(14L);
            customerDao.delete(customer);
    
            /* Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_address as cust_add2_0_0_, customer0_.cust_industry as cust_ind3_0_0_, customer0_.cust_level as cust_lev4_0_0_, customer0_.cust_name as cust_nam5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_source as cust_sou7_0_0_ from cst_customer customer0_ where customer0_.cust_id=? Hibernate: select linkmans0_.lkm_cust_id as lkm_cust9_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_cust_id as lkm_cust9_1_1_, linkmans0_.lkm_email as lkm_emai2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_memo as lkm_memo4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_name as lkm_name6_1_1_, linkmans0_.lkm_phone as lkm_phon7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=? Hibernate: delete from cst_linkman where lkm_id=? Hibernate: delete from cst_linkman where lkm_id=? Hibernate: delete from cst_customer where cust_id=? */
        }
    
    }