Hibernate中双向多对多的两种配置方式

                                                                Hibernate中双向多对多的两种配置方式

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>();
}

<?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> 

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;
    }
}

<?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> 

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;
    }
}

<?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>

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()+"	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();
    }
}

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>();
}

<?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> 

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;
    }
}

<?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> 

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;
    }
}

<?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> 

<?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>

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();
    }
    
}