W3Cschool
恭喜您成為首批注冊用戶
獲得88經(jīng)驗值獎勵
以下代碼顯示如何為多對多映射設置連接表。
下面的代碼來自PersonDaoImpl.java。
package cn.w3cschool.common; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import org.springframework.transaction.annotation.Transactional; @Transactional public class PersonDaoImpl { public void test(){ Department d1 = new Department(); d1.setName("Design"); Department d2 = new Department(); d2.setName("Testing"); Person p1 = new Person("Tom"); p1.getDepartments().add(d1); p1.getDepartments().add(d2); Person p2 = new Person("Jack"); p2.getDepartments().add(d1); p2.getDepartments().add(d2); d1.getPersons().add(p1); d1.getPersons().add(p2); em.persist(p1); em.persist(p2); em.persist(d1); em.persist(d2); } @PersistenceContext private EntityManager em; }
下面的代碼來自Person.java。
package cn.w3cschool.common; import java.util.HashSet; import java.util.Set; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.JoinTable; import javax.persistence.ManyToMany; @Entity public class Person { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private long id; private String name; @ManyToMany @JoinTable(name="PERSON_DEPT", joinColumns=@JoinColumn(name="PERSON_ID"), inverseJoinColumns=@JoinColumn(name="DEPT_ID")) private Set<Department> departments = new HashSet<Department>(); public Person() {} public Person(String name) { this.name = name; } public Set<Department> getDepartments() { return departments; } public void setDepartments(Set<Department> departments) { this.departments = departments; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "Person [id=" + id + ", name=" + name + ", departments=" + departments + "]"; } }
下面的代碼來自Department.java。
package cn.w3cschool.common; import java.util.HashSet; import java.util.Set; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.ManyToMany; @Entity public class Department implements java.io.Serializable{ @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private long id; private String name; @ManyToMany private Set<Person> persons = new HashSet<Person>(); public Set<Person> getPersons() { return persons; } public void setPersons(Set<Person> persons) { this.persons = persons; } public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "Department [id=" + id + ", name=" + name + ", persons=" + persons + "]"; } }下載 ManyToMany_Join_Table.zip
以下是數(shù)據(jù)庫轉儲。
Table Name: DEPARTMENT Row: Column Name: ID, Column Type: BIGINT: Column Value: 1 Column Name: NAME, Column Type: VARCHAR: Column Value: Design Row: Column Name: ID, Column Type: BIGINT: Column Value: 2 Column Name: NAME, Column Type: VARCHAR: Column Value: Testing Table Name: DEPARTMENT_PERSON Row: Column Name: DEPARTMENT_ID, Column Type: BIGINT: Column Value: 1 Column Name: PERSONS_ID, Column Type: BIGINT: Column Value: 1 Row: Column Name: DEPARTMENT_ID, Column Type: BIGINT: Column Value: 1 Column Name: PERSONS_ID, Column Type: BIGINT: Column Value: 2 Table Name: PERSON Row: Column Name: ID, Column Type: BIGINT: Column Value: 1 Column Name: NAME, Column Type: VARCHAR: Column Value: Tom Row: Column Name: ID, Column Type: BIGINT: Column Value: 2 Column Name: NAME, Column Type: VARCHAR: Column Value: Jack Table Name: PERSON_DEPT Row: Column Name: PERSON_ID, Column Type: BIGINT: Column Value: 1 Column Name: DEPT_ID, Column Type: BIGINT: Column Value: 1 Row: Column Name: PERSON_ID, Column Type: BIGINT: Column Value: 1 Column Name: DEPT_ID, Column Type: BIGINT: Column Value: 2 Row: Column Name: PERSON_ID, Column Type: BIGINT: Column Value: 2 Column Name: DEPT_ID, Column Type: BIGINT: Column Value: 1 Row: Column Name: PERSON_ID, Column Type: BIGINT: Column Value: 2 Column Name: DEPT_ID, Column Type: BIGINT: Column Value: 2
Copyright©2021 w3cschool編程獅|閩ICP備15016281號-3|閩公網(wǎng)安備35020302033924號
違法和不良信息舉報電話:173-0602-2364|舉報郵箱:jubao@eeedong.com
掃描二維碼
下載編程獅App
編程獅公眾號
聯(lián)系方式:
更多建議: