Hibernate关联关系之多对多

1 public class Employee {2 ????private Integer empid; ?//员工编号3 ????private String empname; ?//员工姓名4 ????private Set<Project> projects = new HashSet<Project>(); ?//植入项目集合5 }

 1 <?xml version="1.0"?> 2 <!DOCTYPE hibernate-mapping PUBLIC 3 ????????"-//Hibernate/Hibernate Mapping DTD 3.0//EN" 4 ????????"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 5 <hibernate-mapping package="cn.hibernate.day04mapping.manytomany"> 6 ????<!--实体 name=实体端的内容 ??column=DB端的内容--> 7 ????<class name="Employee" table="EMPLOYEE" schema="liutao"> 8 ????????<!--和底层数据表对应的主键 ??业务意义--> 9 ????????<id name="empid" column="EMPNO">10 ???????????<generator class="native"></generator>11 ????????</id>12 ????????<property name="empname" column="EMPNAME"></property>13 ????????<set name="projects" table="REMPPRO">14 ????????????<key column="REMPID"></key>15 ????????????<many-to-many class="Project" column="RPROID"></many-to-many>16 ????????</set>17 ????</class>18 </hibernate-mapping>

1 public class Project {2 ????private Integer proid;3 ????private String proname;4 }

 1 <?xml version="1.0"?> 2 <!DOCTYPE hibernate-mapping PUBLIC 3 ????????"-//Hibernate/Hibernate Mapping DTD 3.0//EN" 4 ????????"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 5 <hibernate-mapping package="cn.hibernate.day04mapping.manytomany"> 6 ????<!--实体 name=实体端的内容 ??column=DB端的内容--> 7 ????<class name="Project" table="PROJECT" schema="liutao"> 8 ????????<!--和底层数据表对应的主键 ??业务意义--> 9 ????????<id name="proid" column="PROID">10 ???????????<generator class="native"></generator>11 ????????</id>12 ????????<property name="proname" column="PRONAME"></property>13 ????</class>14 </hibernate-mapping>

 1 //多对多 单向关联 ?添加一个员工对应多个工程 2 ????@Test 3 ????public void t2(){ 4 ????????Session session = HibernateUtil.getSession(); 5 ????????Transaction tx=session.beginTransaction(); 6 ????????Employee emp1=new Employee(); 7 ????????emp1.setEmpname("曹梅花"); 8 ????????Project pro1=new Project(); 9 ????????pro1.setProname("海淀花园");10 ????????Project pro2=new Project();11 ????????pro2.setProname("三国统治");12 13 ????????emp1.getProjects().add(pro1);14 ????????emp1.getProjects().add(pro2);15 16 ????????session.save(emp1);17 ????????session.save(pro1);18 ????????session.save(pro2);19 ????????tx.commit();20 ????????session.close();21 ????}

 1 <?xml version="1.0"?> 2 <!DOCTYPE hibernate-mapping PUBLIC 3 ????????"-//Hibernate/Hibernate Mapping DTD 3.0//EN" 4 ????????"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 5 <hibernate-mapping package="cn.hibernate.day04mapping.manytomany"> 6 ????<!--实体 name=实体端的内容 ??column=DB端的内容--> 7 ????<class name="Employee" table="EMPLOYEE" schema="liutao"> 8 ????????<!--和底层数据表对应的主键 ??业务意义--> 9 ????????<id name="empid" column="EMPNO">10 ???????????<generator class="native"></generator>11 ????????</id>12 ????????<property name="empname" column="EMPNAME"></property>13 ????????<set name="projects" table="REMPPRO" lazy="true">14 ????????????<key column="REMPID"></key>15 ????????????<many-to-many class="Project" column="RPROID"></many-to-many>16 ????????</set>17 ????</class>18 </hibernate-mapping>

 1 <?xml version="1.0"?> 2 <!DOCTYPE hibernate-mapping PUBLIC 3 ????????"-//Hibernate/Hibernate Mapping DTD 3.0//EN" 4 ????????"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 5 <hibernate-mapping package="cn.hibernate.day04mapping.manytomany"> 6 ????<!--实体 name=实体端的内容 ??column=DB端的内容--> 7 ????<class name="Project" table="PROJECT" schema="liutao"> 8 ????????<!--和底层数据表对应的主键 ??业务意义--> 9 ????????<id name="proid" column="PROID">10 ???????????<generator class="native"></generator>11 ????????</id>12 ????????<property name="proname" column="PRONAME"></property>13 ????????<set name="employees" table="REMPPRO" lazy="true">14 ????????????<key column="RPROID"></key>15 ????????????<many-to-many class="Employee" column="REMPID"></many-to-many>16 ????????</set>17 ????</class>18 </hibernate-mapping>

 1 ??//多对多双向 ?查询指定工程参与人员 2 ????//查询员工所属工程 3 ????@Test 4 ????public void t3(){ 5 ????????Session session = HibernateUtil.getSession(); 6 ????????Transaction tx=session.beginTransaction(); 7 ????????Project project = session.load(Project.class, 42); 8 ????????System.out.println(project.getProname()); 9 ????????for (Employee item:project.getEmployees()10 ?????????????) {11 ????????????System.out.println(item.getEmpname());12 ????????}13 ????????tx.commit();14 ????????session.close();15 ????}