多对多

相当于一个老师可以教多个学生，一个学生也可以有多个老师

数据表中都是再设计一个表寸相关的id

1.多对多单向

1annotation

Student.java

package com.bjsxt.hibernate;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.ManyToOne;

import javax.persistence.Table;

@Entity

public class Student {

    private int id;

    private String name;

    @Id

    @GeneratedValue

    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;

    }

}

teacher.java

package com.bjsxt.hibernate;

import java.util.HashSet;

import java.util.Set;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.JoinColumn;

import javax.persistence.JoinTable;

import javax.persistence.ManyToMany;

import javax.persistence.OneToMany;

import javax.persistence.Table;

@Entity

public class Teacher {

    private int id;

    private String name;

    private Set<Student> students = new HashSet<Student>();

    @Id

    @GeneratedValue

    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;

    }

    @ManyToMany

    @JoinTable(name="t_s",

        joinColumns={@JoinColumn(name="teacher_id")},    //自己这个类的外键id

        inverseJoinColumns={@JoinColumn(name="student_id")}   //对方那张表的外键id

        )

    public Set<Student> getStudents() {

        return students;

    }

    public void setStudents(Set<Student> students) {

        this.students = students;

    }

}

hibernate.cfg.xml

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

<!DOCTYPE hibernate-configuration PUBLIC

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

        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>

        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>

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

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

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

       <!--

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

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

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

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

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

       -->

        <!-- JDBC connection pool (use the built-in) -->

        <property name="connection.pool_size"></property>

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

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

        <!-- Disable the second-level cache  -->

        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->

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

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

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

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

         -->

        <mapping class="com.bjsxt.hibernate.Teacher"/>

        <mapping class="com.bjsxt.hibernate.Student"/>

        <!--

         <mapping resource="com/bjsxt/hibernate/Teacher.hbm.xml"/>

         <mapping resource="com/bjsxt/hibernate/Student.hbm.xml"/>

          -->

    </session-factory>

</hibernate-configuration>

测试代码

package com.bjsxt.hibernate;

import java.util.Date;

import org.hibernate.Query;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.AnnotationConfiguration;

import org.hibernate.tool.hbm2ddl.SchemaExport;

import org.junit.AfterClass;

import org.junit.BeforeClass;

import org.junit.Test;

public class HibernateORMappingTest {

    private static SessionFactory sessionFactory;

    //@BeforeClass

    public static void beforeClass() {

            sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();

    }

    //@AfterClass

    public static void afterClass() {

        sessionFactory.close();

    }

    @Test

    public void testSchemaExport() {

        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);

    }

    public static void main(String[] args) {

        beforeClass();

    }

}

2.xml

student.hbm.xml

<?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>

    <class name="com.bjsxt.hibernate.Student">

        <id name="id">

            <generator class="native"></generator>

        </id>

        <property name="name"></property>

    </class>

</hibernate-mapping>

teacher.hbm.xml

<?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>

    <class name="com.bjsxt.hibernate.Student">

        <id name="id">

            <generator class="native"></generator>

        </id>

        <property name="name"></property>

    </class>

</hibernate-mapping>

hibernate.cfg.xml

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

<!DOCTYPE hibernate-configuration PUBLIC

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

        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>

        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>

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

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

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

       <!--

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

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

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

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

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

       -->

        <!-- JDBC connection pool (use the built-in) -->

        <property name="connection.pool_size"></property>

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

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

        <!-- Disable the second-level cache  -->

        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->

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

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

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

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

         -->

        <!--

        <mapping class="com.bjsxt.hibernate.Teacher"/>

        <mapping class="com.bjsxt.hibernate.Student"/>

         -->

         <mapping resource="com/bjsxt/hibernate/Teacher.hbm.xml"/>

         <mapping resource="com/bjsxt/hibernate/Student.hbm.xml"/>

    </session-factory>

</hibernate-configuration>

多对多双向关联

1.annotation

student.java

package com.bjsxt.hibernate;

import java.util.HashSet;

import java.util.Set;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.ManyToMany;

@Entity

public class Student {

    private int id;

    private String name;

    private Set<Teacher> teachers = new HashSet<Teacher>();

    @ManyToMany(mappedBy="students")

    public Set<Teacher> getTeachers() {

        return teachers;

    }

    public void setTeachers(Set<Teacher> teachers) {

        this.teachers = teachers;

    }

    @Id

    @GeneratedValue

    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;

    }

}

Teacher.java

package com.bjsxt.hibernate;

import java.util.HashSet;

import java.util.Set;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.JoinColumn;

import javax.persistence.JoinTable;

import javax.persistence.ManyToMany;

import javax.persistence.OneToMany;

import javax.persistence.Table;

@Entity

public class Teacher {

    private int id;

    private String name;

    private Set<Student> students = new HashSet<Student>();

    @Id

    @GeneratedValue

    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;

    }

    @ManyToMany

    @JoinTable(name="t_s",

        joinColumns={@JoinColumn(name="teacher_id")},

        inverseJoinColumns={@JoinColumn(name="student_id")}

        )

    public Set<Student> getStudents() {

        return students;

    }

    public void setStudents(Set<Student> students) {

        this.students = students;

    }

}

hibernate.cfg.xml

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

<!DOCTYPE hibernate-configuration PUBLIC

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

        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>

        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>

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

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

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

       <!--

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

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

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

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

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

       -->

        <!-- JDBC connection pool (use the built-in) -->

        <property name="connection.pool_size"></property>

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

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

        <!-- Disable the second-level cache  -->

        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->

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

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

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

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

         -->

          <mapping class="com.bjsxt.hibernate.Teacher"/>

        <mapping class="com.bjsxt.hibernate.Student"/>
  <!--  
<mapping resource="com/bjsxt/hibernate/Teacher.hbm.xml"/> <mapping resource="com/bjsxt/hibernate/Student.hbm.xml"/>
 -->
        
</session-factory> </hibernate-configuration>

test.java

package com.bjsxt.hibernate;

import java.util.Date;

import org.hibernate.Query;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.AnnotationConfiguration;

import org.hibernate.tool.hbm2ddl.SchemaExport;

import org.junit.AfterClass;

import org.junit.BeforeClass;

import org.junit.Test;

public class HibernateORMappingTest {

    private static SessionFactory sessionFactory;

    //@BeforeClass

    public static void beforeClass() {

            sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();

    }

    //@AfterClass

    public static void afterClass() {

        sessionFactory.close();

    }

    @Test

    public void testSchemaExport() {

        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);

    }

    public static void main(String[] args) {

        beforeClass();

    }

}

2。xml

Student.hbm.xml

<?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>

    <class name="com.bjsxt.hibernate.Student">

        <id name="id">

            <generator class="native"></generator>

        </id>

        <property name="name"></property>

        <set name="teachers" table="t_s">

            <key column="student_id"></key>

            <many-to-many class="com.bjsxt.hibernate.Teacher" column="teacher_id"/>

        </set>

    </class>

</hibernate-mapping>

Teacher.hbm.xml

<?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>

    <class name="com.bjsxt.hibernate.Teacher">

        <id name="id">

            <generator class="native"></generator>

        </id>

        <property name="name"></property>

        <set name="students" table="t_s">

            <key column="teacher_id"></key>

            <many-to-many class="com.bjsxt.hibernate.Student" column="student_id"/>

        </set>

    </class>

</hibernate-mapping>

hibernate.cfg.xml

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

<!DOCTYPE hibernate-configuration PUBLIC

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

        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>

        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>

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

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

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

       <!--

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

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

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

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

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

       -->

        <!-- JDBC connection pool (use the built-in) -->

        <property name="connection.pool_size"></property>

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

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

        <!-- Disable the second-level cache  -->

        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->

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

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

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

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

         -->

        <!--  

          <mapping class="com.bjsxt.hibernate.Teacher"/>

        <mapping class="com.bjsxt.hibernate.Student"/>

         -->

        <mapping resource="com/bjsxt/hibernate/Teacher.hbm.xml"/>

         <mapping resource="com/bjsxt/hibernate/Student.hbm.xml"/>

    </session-factory>

</hibernate-configuration>

test一致

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