SpringData-One-to-many table operations

Based on the previous article  Specifications interface dynamic query introductory demo  , let's continue to go deeper

 

1. Create a contact table (it is a many-to-one relationship with the customer table)

/*创建联系人表*/
CREATE TABLE cst_linkman (
  lkm_id BIGINT(32) NOT NULL AUTO_INCREMENT COMMENT '联系人编号(主键)',
  lkm_name VARCHAR(16) DEFAULT NULL COMMENT '联系人姓名',
  lkm_gender CHAR(1) DEFAULT NULL COMMENT '联系人性别',
  lkm_phone VARCHAR(16) DEFAULT NULL COMMENT '联系人办公电话',
  lkm_mobile VARCHAR(16) DEFAULT NULL COMMENT '联系人手机',
  lkm_email VARCHAR(64) DEFAULT NULL COMMENT '联系人邮箱',
  lkm_position VARCHAR(16) DEFAULT NULL COMMENT '联系人职位',
  lkm_memo VARCHAR(512) DEFAULT NULL COMMENT '联系人备注',
  lkm_cust_id BIGINT(32) NOT NULL COMMENT '客户id(外键)',
  PRIMARY KEY (`lkm_id`),
  KEY `FK_cst_linkman_lkm_cust_id` (`lkm_cust_id`),
  CONSTRAINT `FK_cst_linkman_lkm_cust_id` FOREIGN KEY (`lkm_cust_id`) REFERENCES `cst_customer` (`cust_id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=INNODB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

2. Create an entity class for the contact table in the database

package com.cast.domain;
 
import java.io.Serializable;
import javax.persistence.*;
 
/**
 * 封装数据库中表的实体类
 */
@Entity    //该类是一个数据库表实体封装类
@Table(name = "cst_linkman")    //指定数据库中对应表名
public class Customer implements Serializable {
 
    @Id    //主键
    @GeneratedValue(strategy = GenerationType.IDENTITY)    //主键自增
    @Column(name = "lkm_id")    //数据库表中的列名
    private Long lkmId;    //联系人编号(主键)

    @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;    //联系人邮箱

    @Column(name = "lkm_position")
    private String lkmPosition;    //联系人职位

    @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(targetEntity = Customer.class, fetch = FetchType.LAZY)
    @JoinColumn(name = "lkm_cust_id", referencedColumnName = "cust_id")
    private Customer customer;
 
    // getter setter 方法....
 
    // toString() 方法....

}

3. Create a dao layer interface specification that conforms to SpringDataJpa

public interface LinkManDao extends JpaRepository<LinkMan, Long>, JpaSpecificationExecutor<LinkMan> {

}

Four. Add one-to-many annotation configuration to the Customer package class

@OneToMany(targetEntity = LinkMan.class)
@JoinColumn(name = "lkm_cust_id",referencedColumnName = "cust_id")
private Set<LinkMan> linkMans = new HashSet<>();

5. Create a new test class

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class OneToManyTest {

    @Autowired
    private CustomerDao customerDao;

    @Autowired
    private LinkManDao linkManDao;


}

1. How to add data

Configure the customer-to-contact relationship:

@Test
@Transactional  //配置事务
@Rollback(false)  //不自动回滚
public void testAddByCustomer() {
    //创建一个客户
    Customer customer = new Customer();
    customer.setCustName("张三");
    customer.setCustAddress("武汉市汉阳区");
    //创建一个联系人
    LinkMan linkMan = new LinkMan();
    linkMan.setLkmName("小李");
    linkMan.setLkmPhone("1313131313");
    //配置客户到联系人的关系
    customer.getLinkMans().add(linkMan);

    customerDao.save(customer);
    linkManDao.save(linkMan);
}

Configure the contact-to-customer relationship:

@Test
@Transactional  //配置事务
@Rollback(false)  //不自动回滚
public void testAddByLinkman() {
    //创建一个客户
    Customer customer = new Customer();
    customer.setCustName("张三");
    customer.setCustAddress("武汉市汉阳区");
    //创建一个联系人
    LinkMan linkMan = new LinkMan();
    linkMan.setLkmName("小李");
    linkMan.setLkmPhone("1313131313");
    //配置联系人到客户的关系
    linkMan.setCustomer(customer);

    customerDao.save(customer);
    linkManDao.save(linkMan);
}

The following operations will generate a repeated update sql statement:

@Test
@Transactional  //配置事务
@Rollback(false)  //不自动回滚
public void testAdd() {
    //创建一个客户
    Customer customer = new Customer();
    customer.setCustName("张三");
    customer.setCustAddress("武汉市汉阳区");
    //创建一个联系人
    LinkMan linkMan = new LinkMan();
    linkMan.setLkmName("小李");
    linkMan.setLkmPhone("1313131313");
    //配置客户到联系人
    customer.getLinkMans().add(linkMan);
    //配置联系人到客户
    linkMan.setCustomer(customer);

    customerDao.save(customer);
    linkManDao.save(linkMan);
}

The customer abandoning the associated foreign key can solve the problem:

*** The value of mappedBy is a member variable of Customer defined in the contact package class

//@OneToMany(targetEntity = LinkMan.class)
//@JoinColumn(name = "lkm_cust_id", referencedColumnName = "cust_id")
@OneToMany(mappedBy = "customer")   //放弃关联外键维护权  配置此注解
private Set<LinkMan> linkMans = new HashSet();

2. Cascading addition: When saving a customer, the contacts associated with the customer are also saved

* Modify the comment on the member attribute in the customer package contact person:

(CascadeType.ALL is to cascade all operations)

(CascadeType.MERGE is a cascading update operation)

(CascadeType.PERSIST is a cascade save operation)

(CascadeType.REMOVE is a cascade delete operation)

@OneToMany(mappedBy = "customer", cascade = CascadeType.ALL)
private Set<LinkMan> linkMans = new HashSet();

* Write the method of cascading addition:

@Test
@Transactional  //配置事务
@Rollback(false)  //不自动回滚
public void testCascadeAdd() {
    //创建一个客户
    Customer customer = new Customer();
    customer.setCustName("小张");
    customer.setCustAddress("武汉市汉阳区");
    //创建一个联系人
    LinkMan linkMan = new LinkMan();
    linkMan.setLkmName("小陈");
    linkMan.setLkmPhone("1313131313");
    //配置联系人到客户
    linkMan.setCustomer(customer);
    //配置客户到联系人
    customer.getLinkMans().add(linkMan);
    
    customerDao.save(customer);
}

3. Cascading delete: When deleting a customer, the contacts associated with the customer are also deleted

* Write the method of cascading deletion:

@Test
@Transactional  //配置事务
@Rollback(false)  //不自动回滚
public void testCascadeDelete() {
    //查询到指定 id 客户
    Customer customer = customerDao.findOne(1L);
    //执行删除该 id 客户
    customerDao.delete(customer);
}

 

Source code download:  https://pan.baidu.com/s/1ovQIFOHe3sT4ROFop4BM1A