Hibernate中双向多对多的两种配置方式

2022-11-04 21:17:12

1.建立多对多双向关联关系

 package cn.happy.entitys;

 import java.util.HashSet;

 import java.util.Set;

 public class Employee {

     private Integer empid;

     private String empname;

     private Set<ProEmp> emps = new HashSet<ProEmp>();

     public Set<ProEmp> getEmps() {

         return emps;

     }

     public void setEmps(Set<ProEmp> emps) {

         this.emps = emps;

     }

     public Integer getEmpid() {

         return empid;

     }

     public void setEmpid(Integer empid) {

         this.empid = empid;

     }

     public String getEmpname() {

         return empname;

     }

     public void setEmpname(String empname) {

         this.empname = empname;

     }

     public Set<ProEmp> getProjects() {

         return projects;

     }

     public void setProjects(Set<ProEmp> projects) {

         this.projects = projects;

     }

     private Set<ProEmp> projects = new HashSet<ProEmp>();

 }

Employee.java

 <?xml version="1.0"?>

 <!DOCTYPE hibernate-mapping PUBLIC

         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

         <hibernate-mapping package="cn.happy.entitys">

         <class name="Employee" table="EMPLOYEE">

         <id name="empid" column="EMPID">

          <generator class="sequence">

          <param name="sequence">STU_SID</param>

          </generator>

         </id>

         <property name="empname" type="string" column="EMPNAME"></property>

         <set name="projects" table="PROEMP" cascade="save-update">

         <key column="REMPID"></key>

         <many-to-many class="Project" column="RPROID"></many-to-many>

         </set>

         </class>

         </hibernate-mapping>

Employee.hbm.xml

 package cn.happy.entitys;

 import java.util.Set;

 public class Project {

     private Integer proid;

     private String proname;

     private Set<ProEmp> pros;

     public Integer getProid() {

         return proid;

     }

     public Set<ProEmp> getPros() {

         return pros;

     }

     public void setPros(Set<ProEmp> pros) {

         this.pros = pros;

     }

     public void setProid(Integer proid) {

         this.proid = proid;

     }

     public String getProname() {

         return proname;

     }

     public void setProname(String proname) {

         this.proname = proname;

     }

 }

Project.java

 <?xml version="1.0"?>

 <!DOCTYPE hibernate-mapping PUBLIC

         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

         <hibernate-mapping package="cn.happy.entity">

         <class name="Project" table="PROJECT">

         <id name="proid" column="PROID">

          <generator class="sequence">

          <param name="sequence">STU_SID</param>

          </generator>

         </id>

         <property name="proname" type="string" column="PRONAME"></property>

         <set name="employeses" table="PROEMP" cascade="save-update">

         <key column="RPROID"></key>

         <many-to-many class="Employee" column="REMPID"></many-to-many>

         </set>

         </class>

         </hibernate-mapping>

Project.hbm.xml

中间关系表

 package cn.happy.entitys;

 public class ProEmp {

     private Integer id;

     private Project pro;

     private Employee emp;

     public Integer getId() {

         return id;

     }

     public void setId(Integer id) {

         this.id = id;

     }

     public Project getPro() {

         return pro;

     }

     public void setPro(Project pro) {

         this.pro = pro;

     }

     public Employee getEmp() {

         return emp;

     }

     public void setEmp(Employee emp) {

         this.emp = emp;

     }

 }

ProEmp.java

 <?xml version='1.0' encoding='utf-8'?>

 <!DOCTYPE hibernate-configuration PUBLIC

         "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

 <hibernate-configuration>

     <session-factory>

         <!-- Database connection settings -->

         <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>

         <property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>

         <property name="connection.username">hmy</property>

         <property name="connection.password">hmy</property>

         <!-- SQL dialect SQL方言-->

         <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>

         <!-- Echo all executed SQL to stdout 控制台显示-->

         <property name="show_sql">true</property>

         <!-- Enable Hibernate's automatic session context management -->

         <property name="current_session_context_class">thread</property>

         <!-- 是否格式化 -->

         <property name="format_sql">true</property>

         <!-- Drop and re-create the database schema on startup -->

         <property name="hbm2ddl.auto">create</property>

         <!-- <mapping resource="cn/happy/entity/Student.hbm.xml" /> -->

         <!-- <mapping resource="cn/happy/entity/grade.hbm.xml" /> -->

         <!-- <mapping class="cn.happy.entity.Grade"/> -->

         <!-- <mapping resource="cn/happy/entity/Dept.hbm.xml" />

         <mapping resource="cn/happy/entity/Emp.hbm.xml" /> -->

         <mapping resource="cn/happy/entity/Employee.hbm.xml" />

         <mapping resource="cn/happy/entity/Project.hbm.xml" /> 

         <!-- <mapping resource="cn/happy/entitys/Employee.hbm.xml" />

         <mapping resource="cn/happy/entitys/Project.hbm.xml" />

         <mapping resource="cn/happy/entitys/ProEmp.hbm.xml" /> -->

     </session-factory>

 </hibernate-configuration>

hibernate.hbm.xml

 package cn.happy.ui;

 import org.hibernate.Session;

 import org.hibernate.Transaction;

 import cn.happy.entity.Employee;

 import cn.happy.entity.Project;

 import cn.happy.util.HibernateUtil;

 public class Test3 {

     public static void main(String[] args) {

         select();

     }

     /**

      * 检索

      * */

     public static void select(){

         Session session = HibernateUtil.currentSession();

         Project pro = (Project)session.load(Project.class, 1);

         for (Employee item : pro.getEmployeses()) {

             System.out.println("员工："+item.getEmpname()+"\t参加的项目:");

             for (Project project : item.getProjects()) {

                 System.out.println(project.getProname());

             }

         }

         HibernateUtil.closeSession();

     }

     /**

      * 添加

      * */

     public static void one(){

         Session session = HibernateUtil.currentSession();

         Transaction tx = session.beginTransaction();

         Project pro=new Project();

         pro.setProname("ADO");

         Employee emp=new Employee();

         emp.setEmpname("范子阳");

         Employee emp2=new Employee();

         emp2.setEmpname("李夏鹏");

         pro.getEmployeses().add(emp);

         pro.getEmployeses().add(emp2);

         //未声明级联

         //emp.getProjects().add(pro);

         //emp2.getProjects().add(pro);

         session.save(pro);

         tx.commit();

         HibernateUtil.closeSession();

     }

 }

测试类

2.建立多对多双向关联拆成两个一对多

 package cn.happy.entitys;

 import java.util.HashSet;

 import java.util.Set;

 public class Employee {

     private Integer empid;

     private String empname;

     private Set<ProEmp> emps = new HashSet<ProEmp>();

     public Set<ProEmp> getEmps() {

         return emps;

     }

     public void setEmps(Set<ProEmp> emps) {

         this.emps = emps;

     }

     public Integer getEmpid() {

         return empid;

     }

     public void setEmpid(Integer empid) {

         this.empid = empid;

     }

     public String getEmpname() {

         return empname;

     }

     public void setEmpname(String empname) {

         this.empname = empname;

     }

     public Set<ProEmp> getProjects() {

         return projects;

     }

     public void setProjects(Set<ProEmp> projects) {

         this.projects = projects;

     }

     private Set<ProEmp> projects = new HashSet<ProEmp>();

 }

Employee.java

 <?xml version="1.0"?>

 <!DOCTYPE hibernate-mapping PUBLIC

         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

         <hibernate-mapping package="cn.happy.entitys">

         <class name="Employee" table="EMPLOYEE">

         <id name="empid" column="EMPID">

          <generator class="sequence">

          <param name="sequence">STU_SID</param>

          </generator>

         </id>

         </class>

         </hibernate-mapping>

Employee.hbm.xml

 package cn.happy.entitys;

 import java.util.Set;

 public class Project {

     private Integer proid;

     private String proname;

     private Set<ProEmp> pros;//为中间关系表所对应的实体类的类型

     public Integer getProid() {

         return proid;

     }

     public Set<ProEmp> getPros() {

         return pros;

     }

     public void setPros(Set<ProEmp> pros) {

         this.pros = pros;

     }

     public void setProid(Integer proid) {

         this.proid = proid;

     }

     public String getProname() {

         return proname;

     }

     public void setProname(String proname) {

         this.proname = proname;

     }

 }

Project.java

 <?xml version="1.0"?>

 <!DOCTYPE hibernate-mapping PUBLIC

         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

         <hibernate-mapping package="cn.happy.entitys">

         <class name="Project" table="PROJECT">

         <id name="proid" column="PROID">

          <generator class="sequence">

          <param name="sequence">STU_SID</param>

          </generator>

         </id>

         <property name="proname" type="string" column="PRONAME"></property>

         </class>

         </hibernate-mapping>

Project.hbm.xml

 package cn.happy.entitys;

 public class ProEmp {

     private Integer id;

     private Project pro;

     private Employee emp;

     public Integer getId() {

         return id;

     }

     public void setId(Integer id) {

         this.id = id;

     }

     public Project getPro() {

         return pro;

     }

     public void setPro(Project pro) {

         this.pro = pro;

     }

     public Employee getEmp() {

         return emp;

     }

     public void setEmp(Employee emp) {

         this.emp = emp;

     }

 }

ProEmp.java

 <?xml version="1.0"?>

 <!DOCTYPE hibernate-mapping PUBLIC

         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

         <hibernate-mapping package="cn.happy.entitys">

         <class name="ProEmp" table="PROEMP">

         <id name="id" column="ID">

          <generator class="sequence">

          <param name="sequence">STU_SID</param>

          </generator>

         </id>

         <many-to-one name="emp" class="Employee" column="empid"></many-to-one>

         <many-to-one name="pro" class="Project" column="proid"></many-to-one>

         </class>

         </hibernate-mapping>

ProEmp.hbm.xml

 <?xml version='1.0' encoding='utf-8'?>

 <!DOCTYPE hibernate-configuration PUBLIC

         "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

 <hibernate-configuration>

     <session-factory>

         <!-- Database connection settings -->

         <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>

         <property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>

         <property name="connection.username">hmy</property>

         <property name="connection.password">hmy</property>

         <!-- SQL dialect SQL方言-->

         <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>

         <!-- Echo all executed SQL to stdout 控制台显示-->

         <property name="show_sql">true</property>

         <!-- Enable Hibernate's automatic session context management -->

         <property name="current_session_context_class">thread</property>

         <!-- 是否格式化 -->

         <property name="format_sql">true</property>

         <!-- Drop and re-create the database schema on startup -->

         <property name="hbm2ddl.auto">create</property>

         <!-- <mapping resource="cn/happy/entity/Student.hbm.xml" /> -->

         <!-- <mapping resource="cn/happy/entity/grade.hbm.xml" /> -->

         <!-- <mapping class="cn.happy.entity.Grade"/> -->

         <!-- <mapping resource="cn/happy/entity/Dept.hbm.xml" />

         <mapping resource="cn/happy/entity/Emp.hbm.xml" /> -->

         <!-- <mapping resource="cn/happy/entity/Employee.hbm.xml" />

         <mapping resource="cn/happy/entity/Project.hbm.xml" />  -->

         <mapping resource="cn/happy/entitys/Employee.hbm.xml" />

         <mapping resource="cn/happy/entitys/Project.hbm.xml" />

         <mapping resource="cn/happy/entitys/ProEmp.hbm.xml" />

     </session-factory>

 </hibernate-configuration>

Hinernate.hbm.xml

 package cn.happy.ui;

 import org.hibernate.Session;

 import org.hibernate.Transaction;

 import cn.happy.entitys.Employee;

 import cn.happy.entitys.ProEmp;

 import cn.happy.entitys.Project;

 import cn.happy.util.HibernateUtil;

 public class Test4 {

     public static void main(String[] args) {

         test();

     }

     public static void test(){

         Session session = HibernateUtil.currentSession();

         Transaction tx = session.beginTransaction();

         Project pro=new Project();

         pro.setProname("ADO");

         Employee emp=new Employee();

         emp.setEmpname("范子阳");

         ProEmp proemp=new ProEmp();

         proemp.setEmp(emp);

         proemp.setPro(pro);

         session.save(proemp);

         session.save(emp);

         session.save(pro);

         tx.commit();

         HibernateUtil.closeSession();

     }

 }

测试类

码农公寓

1.建立多对多双向关联关系

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