Hibernate的list:多对多

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Student.java
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package blog.hibernate.domain;import java.util.ArrayList;import java.util.List;public class Student {    private int id;    private String name;    private List<Teacher> teachers = new ArrayList<Teacher>();    public List<Teacher> getTeachers() {        return teachers;    }    public void setTeachers(List<Teacher> teachers) {        this.teachers = teachers;    }        public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "Student{" + "id=" + id + ", name=" + name + '}';    }}

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Student.hbm.xml
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<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping package="blog.hibernate.domain">    <class name="Student" table="students">        <id name="id" column="student_id">            <generator class="native"></generator>        </id>        <property name="name" column="student_name"></property>                           <list name="teachers" table="teacher_student">             <key column="student_id"></key>             <list-index column="index" ></list-index>             <many-to-many class="Teacher" column="teacher_id"></many-to-many>         </list>    </class></hibernate-mapping>

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Teacher.java
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package blog.hibernate.domain;import java.util.ArrayList;import java.util.List;public class Teacher {    private int id;    private String name;    private String course;    private List<Student> students = new ArrayList<Student>();    public List<Student> getStudents() {        return students;    }    public void setStudents(List<Student> students) {        this.students = students;    }    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getCourse() {        return course;    }    public void setCourse(String course) {        this.course = course;    }    @Override    public String toString() {        return "Teacher{" + "id=" + id + ", name=" + name + ", course=" + course + '}';    }}

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Teacher.hbm.xml
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<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping package="blog.hibernate.domain">    <class name="Teacher" table="teachers">        <id name="id" column="teacher_id">            <generator class="native"></generator>        </id>        <property name="name" column="teacher_name"></property>        <property name="course"></property>                           <list name="students" table="teacher_student">             <key column="teacher_id" ></key>             <list-index column="index"></list-index>            <many-to-many class="Student" column="student_id"></many-to-many>         </list>    </class></hibernate-mapping>

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hibernate.cfg.xml
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<?xml version='1.0' encoding='utf-8'?><!DOCTYPE hibernate-configuration PUBLIC    "-//Hibernate/Hibernate Configuration DTD//EN"    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><hibernate-configuration>    <session-factory>        <property name="hibernate.connection.driver_class">org.gjt.mm.mysql.Driver</property>        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/list</property><!-- ///表示连接本机的数据库//localhost:3306 -->        <property name="hibernate.connection.username">root</property>        <property name="hibernate.connection.password">1234</property>        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>                   <property name="hibernate.hbm2ddl.auto">create</property>        <property name="hibernate.show_sql">true</property>                        <mapping resource="blog/hibernate/domain/Student.hbm.xml"/>        <mapping resource="blog/hibernate/domain/Teacher.hbm.xml"/>        <!--        <mapping resource="blog/hibernate/domain/Nation.hbm.xml"/>        <mapping resource="blog/hibernate/domain/City.hbm.xml"/>-->    </session-factory>    </hibernate-configuration>

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HibernateUtil.java
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package blog.hibernate;import java.util.logging.Level;import java.util.logging.Logger;import org.hibernate.HibernateException;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;public final class HibernateUtil {        private static SessionFactory sessionFactory;    private HibernateUtil(){}        static{        Configuration cfg = new Configuration();        sessionFactory =  cfg.configure("hibernate.cfg.xml").buildSessionFactory();    }        public static SessionFactory getSessionFactory(){        return sessionFactory;    }        public static Session getSession(){        return sessionFactory.openSession();    }}

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juint test：Many2Many.java
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package juint.test;import org.hibernate.Session;import org.hibernate.Transaction;import org.junit.BeforeClass;import org.junit.Test;import blog.hibernate.HibernateUtil;import blog.hibernate.domain.Student;import blog.hibernate.domain.Teacher;import java.util.ArrayList;import java.util.List;import java.util.logging.Level;import java.util.logging.Logger;/** * list * @author Administrator */public class Many2Many {    @BeforeClass    public static void setUpBeforeClass() throws Exception {    }    @Test    public void test() {        add();        query();    }    public void add() {        Teacher t1 = new Teacher();        t1.setName("t1");        Teacher t2 = new Teacher();        t2.setName("t2");        List<Teacher> ts = new ArrayList<Teacher>();        ts.add(t1);        ts.add(t1);        Student s1 = new Student();        s1.setName("s1");        Student s2 = new Student();        s2.setName("s2");        List<Student> ss = new ArrayList<Student>();        ss.add(s1);        ss.add(s2);                t1.getStudents().add(s1);        t1.getStudents().add(s2);                t2.getStudents().add(s1);        t2.getStudents().add(s2);//        t1.setStudents(ss);//        t2.setStudents(ss);        /*    s1.setTeachers(ts);        s2.setTeachers(ts);*/        Session session = null;        Transaction tx = null;        try {            session = HibernateUtil.getSession();            tx = session.beginTransaction();            session.save(t1);            session.save(t2);            session.save(s1);            session.save(s2);            tx.commit();        } catch (Exception e) {            Logger.getLogger(Many2Many.class.getName()).log(Level.SEVERE, null, e);            if (tx != null) {                tx.rollback();            }        } finally {            if (session != null) {                session.close();            }        }    }    public void query() {        Session session = null;        try {            session = HibernateUtil.getSession();            Teacher teacher = (Teacher) session.get(Teacher.class, 1);            System.out.println(teacher.getStudents().size());        } catch (Exception e) {            Logger.getLogger(Many2Many.class.getName()).log(Level.SEVERE, null, e);        } finally {            if (session != null) {                session.close();            }        }    }}