求一个Hibernate多对多自身关联的例子代码

Question

1.建表 create   table  student
(sid  varchar ( 32 )  not   null   primary   key ,
 sname  varchar ( 16 ),
 sage  varchar ( 16 ),
) create   table  course
(cid  varchar ( 32 )  not   null   primary   key ,
cname  varchar ( 16 )
) create   table  student_course_link
(sid  varchar ( 32 )  not   null ,
cid  varchar ( 32 )  not   null ,
 primary   key (sid,cid)
)
 2.写VO
StudentVO
package com.test;
import java.util.Set;
public class Student
{
    private String sid;
    private String sname;
    private String sage;    private Set course;
    public Student()
    {
    }
   //写上get setCourse vo
package com.test;import java.util.Set;public class Course
{
    private String cid;
    private String cname;
    private Set student;
   //写上get set
写配置文件
Student.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
    PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd"><hibernate-mapping>    <class name="com.test.Student" table="student" >        <id name="sid" type="string" unsaved-value="null" >
            <column name="sid" sql-type="char(32)" not-null="true"/>
            <generator class="uuid.hex"/>
        </id>        <property name="sname">
            <column name="sname" sql-type="varchar(16)" not-null="true"/>
        </property>        <property name="sage">
            <column name="sage" sql-type="varchar(16)" not-null="true"/>
        </property>        <set name="course" table="student_course_link" cascade="all" outer-join="false">
            <key column="sid"/>
            <many-to-many class="com.test.Course" column="cid"/>
        </set>
   
    </class></hibernate-mapping>
Course.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
    PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd"><hibernate-mapping>    <class name="com.test.Course" table="course" >        <id name="cid" type="string" unsaved-value="null" >
            <column name="cid" sql-type="char(32)" not-null="true"/>
            <generator class="uuid.hex"/>
        </id>        <property name="cname">
            <column name="cname" sql-type="varchar(16)" not-null="true"/>
        </property>        <set name="student" table="student_course_link" lazy="false" cascade="all">
            <key column="cid"/>
            <many-to-many class="com.test.Student" column="sid"/>
        </set>
   
    </class></hibernate-mapping>
接着把下面的hibernate.properties文件拷到classes目录下。。这里用的是mysql
hibernate.query.substitutions true 1, false 0, yes 'Y', no 'N'
## MySQL
hibernate.dialect net.sf.hibernate.dialect.MySQLDialect
hibernate.connection.driver_class org.gjt.mm.mysql.Driver
hibernate.connection.url jdbc:mysql://localhost:3306/wjcms
hibernate.connection.username root
hibernate.connection.password wujun
hibernate.connection.pool_size 1
hibernate.proxool.pool_alias pool1
hibernate.show_sql true
hibernate.jdbc.batch_size 0
hibernate.max_fetch_depth 1
hibernate.cache.use_query_cache true 写测试类了..
package com.test;import net.sf.hibernate.Session;
import net.sf.hibernate.SessionFactory;
import net.sf.hibernate.cfg.Configuration;
import net.sf.hibernate.*;
import java.util.Set;
import java.util.HashSet;
import java.sql.*;
import java.util.List;
import java.util.Iterator;public class TestManyToMany
{
    SessionFactory sf;
    Session session;
    public TestManyToMany()
    {
        try
        {
            Configuration cfg = new Configuration();
            sf = cfg.addClass(Student.class).addClass(Course.class).buildSessionFactory();
        }
        catch(HibernateException ex)
        {
            ex.printStackTrace();
        }
    }
    public void doCreate()
    {
        try
        {
            session = sf.openSession();            Student student = new Student();
            student.setSname("小王");
            student.setSage("22");            Set courseSet = new HashSet();
            Course course = null;
            for(int i=0;i<2;i++)
            {
                course = new Course();
                if(i==0)
                    course.setCname("c++");
                else if(i==1)
                    course.setCname("java");
                courseSet.add(course);
            }
            student.setCourse(courseSet);
            
            session.save(student);
            session.flush();
            session.connection().commit();        }
        catch(HibernateException ex)
        {
            ex.printStackTrace();
        }
        catch(SQLException ex1)
        {
            ex1.printStackTrace();
        }
        finally
        {
                try{
                    session.close();
                }
                catch(HibernateException ex2){
                }
        }    }
    public void doQuery()
    {
        try{
            session = sf.openSession();
            Query q = session.createQuery("select s from Student as s");
            List l = q.list();
            Student s = null;
            Course course = null;
            for(int i=0;i<l.size();i++)
            {
                s = (Student)l.get(i);
                System.out.println("姓名： "+s.getSname());
                System.out.println("年龄： "+s.getSage());
                System.out.println("所选的课程：");
                Iterator it = s.getCourse().iterator();
                while(it.hasNext())
                {
                    course = (Course)it.next();
                    System.out.println("课程名： "+course.getCname());
                }
            }        }
        catch(HibernateException ex){
            ex.printStackTrace();
        }
        finally{
            try{
                session.close();
            }
            catch(HibernateException ex2){
            }
        }
    }
    public static void main(String[] args)
    {
        TestManyToMany t = new TestManyToMany();
        //t.doCreate();
        t.doQuery();
    }
}
 

Answer 1

rewfaw
import com.a.Test;

Answer 2

我也正好要这样一个例子。有结果请发一份给我谢谢。[email protected]

Answer 3

背景说明：论坛中每个用户(Admin类)有多个好友，每个好友，可以是多个用户的好友。应该是多对多的关系吧。哈哈。
Admin类代码：
package com.soonj.entity;import java.util.HashSet;
import java.util.Set;
public class Admin { private Integer aid;//

private String adminName;//admin's name--unique

private String password;//admin's password

private String authDay;//authorize day

private Set<Admin> friends = new HashSet<Admin>();

private Set<AdminMessage> messages = new HashSet<AdminMessage>();

public void addFriend(Admin friend){
friends.add(friend);
}

public void addMessage(AdminMessage message){
messages.add(message);
message.setBelonger(this);
}

public Set<Admin> getFriends() {
return friends;
} public void setFriends(Set<Admin> friends) {
this.friends = friends;
} public String getAdminName() {
return adminName;
} public void setAdminName(String adminName) {
this.adminName = adminName;
} public Integer getAid() {
return aid;
} public void setAid(Integer aid) {
this.aid = aid;
} public String getAuthDay() {
return authDay;
} public void setAuthDay(String authDay) {
this.authDay = authDay;
} public String getPassword() {
return password;
} public void setPassword(String password) {
this.password = password;
} public Set<AdminMessage> getMessages() {
return messages;
} public void setMessages(Set<AdminMessage> messages) {
this.messages = messages;
}}

Answer 4

admin类的 hibernate文件Admin.hbm.xml内容（注释中有简单说明）：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.soonj.entity">
<class name="Admin" table="admins">
<id name="aid" column="aid" type="java.lang.Integer">
<generator class="increment"></generator>
</id>
<property name="adminName" column="adminName" not-null="true" unique="true"></property>
<property name="password" column="password" not-null="true"></property>
<property name="authDay" column="authDay" not-null="true"></property>
<set name="friends" table="adminfriends" cascade="save-update" lazy="false" inverse="false">
<key column="affid"></key><!-- 副表关联主表的外键  -->
<many-to-many class="Admin" column="fafid"/><!-- 主表关联副表的外键  -->
</set>
<set name="messages" cascade="save-update" lazy="false" inverse="true">
<key column="mfid"></key>
<one-to-many class="AdminMessage"/>
</set>
</class>
</hibernate-mapping>
不让连发三次，只能这样了。