Hibernate三种映射关系

many-to-many

 

     一个学生有多个老师，一个老师也有多个学生。现在就在 student 和 teacher 这两张表的基础上增加了一张关系表 t_s ， t_s 为自动生成的表。

 

类代码：

 

Student.java   package com.entity;   import java.util.Set;   /**   * @hibernate .class table="student"   * @author Administrator   *   */   public class Student {     private int id ;       private String sname ;       private Set teacherSet ;       /**       * @hibernate .id generator - class="native"       * @return       */         public int getId() {        return id ;     }       public void setId( int id) {        this . id = id;     }       /**       * @hibernate .property column="sname";       * @return       */         public String getSname() {        return sname ;     }       public void setSname(String sname) {        this . sname = sname;     }       /**       * @hibernate .set table="t_s" cascade="all" lazy="false" inverse="true"       * @hibernate .collection - key column="s_id"       * @hibernate .collection - many - to - many class="com.entity.Teacher" column="t_id"       * @return       */         public Set getTeacherSet() {        return teacherSet ;     }       public void setTeacherSet(Set teacherSet) {        this . teacherSet = teacherSet;     } }

 

Teacher.java   package com.entity;   import java.util.Set;   /**   * @hibernate .class table="teacher"   * @author Administrator   *   */   public class Teacher {     private int id ;       private String tname ;       private Set studentSet ;       /**       * @hibernate .id generator - class="native"       * @return       */         public int getId() {        return id ;     }       public void setId( int id) {        this . id = id;     }       /**       * @hibernate .set table="t_s" cascade="all" lazy="false"       * @hibernate .collection - key column="t_id"       * @hibernate .collection - many - to - many class="com.entity.Student" column="s_id"       * @return       */         public Set getStudentSet() {        return studentSet ;     }       public void setStudentSet(Set studentSet) {        this . studentSet = studentSet;     }       /**       * @hibernate .property column="tname"       * @return       */         public String getTname() {        return tname ;     }       public void setTname(String tname) {        this . tname = tname;     }   }

 

映射文件：

 

Student.hbm.xml   <? 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 >     < class name = "com.entity.Student" table = "student" >          < id name = "id" column = "id" type = "int" >            < generator class = "native" >               <!--                    To add non XDoclet generator parameters, create a file named                   hibernate-generator-params-Student.xml                   containing the additional parameters and place it in your merge dir.               -->            </ generator >        </ id >          < property name = "sname" type = "java.lang.String" update = "true"            insert = "true" column = "sname" />          < set name = "teacherSet" table = "t_s" lazy = "false" inverse = "true"            cascade = "all" sort = "unsorted" >              < key column = "s_id" ></ key >              < many-to-many class = "com.entity.Teacher" column = "t_id"               outer-join = "auto" />          </ set >          <!--            To add non XDoclet property mappings, create a file named            hibernate-properties-Student.xml            containing the additional properties and place it in your merge dir.        -->       </ class >   </ hibernate-mapping >

 

Teacher.hbm.xml   <? 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 >     < class name = "com.entity.Teacher" table = "teacher" >          < id name = "id" column = "id" type = "int" >            < generator class = "native" >               <!--                    To add non XDoclet generator parameters, create a file named                   hibernate-generator-params-Teacher.xml                   containing the additional parameters and place it in your merge dir.               -->            </ generator >        </ id >          < set name = "studentSet" table = "t_s" lazy = "false" cascade = "all"            sort = "unsorted" >              < key column = "t_id" ></ key >              < many-to-many class = "com.entity.Student" column = "s_id"               outer-join = "auto" />          </ set >          < property name = "tname" type = "java.lang.String" update = "true"            insert = "true" column = "tname" />          <!--            To add non XDoclet property mappings, create a file named            hibernate-properties-Teacher.xml            containing the additional properties and place it in your merge dir.        -->       </ class >   </ hibernate-mapping >

 

one-to-many

 

     假设有2张表student和teacher，一学生只有一个老师，一个老师有多个学生。

 

类代码：

 

Student.java   package com.entity;   /**   * @hibernate .class table="student"   * @author Administrator   *   */ public class Student {     private int id ;       private String sname ;       private Teacher teacher ;       /**       * @hibernate .id column="id" generator - class="native"       * @return       */         public int getId() {        return id ;     }       public void setId( int id) {        this . id = id;     }       /**       * @hibernate .property column="sname"       * @return       */         public String getSname() {        return sname ;     }       public void setSname(String sname) {        this . sname = sname;     }       /**       * @hibernate .many - to - one class="com.entity.Teacher"       * column="t_id"       * cascade="all"       * @return       */         public Teacher getTeacher() {        return teacher ;     }       public void setTeacher(Teacher teacher) {        this . teacher = teacher;     } }

 

Teacher.java   package com.entity;   import java.util.Set;   /**   * @hibernate .class table="teacher"   * @author Administrator   *   */   public class Teacher {     private int id ;       private String tname ;       private Set students ;       /**       * @hibernate .id column="id" generator - class="native"       * @return       */         public int getId() {        return id ;     }       public void setId( int id) {        this . id = id;     }       /**       * @hibernate .set cascade="all" inverse="true" lazy="false"       * @hibernate .collection - key column="t_id"       * @hibernate .collection - one - to - many class="com.entity.Student"       * @return       */         public Set getStudents() {        return students ;     }       public void setStudents(Set students) {        this . students = students;     }       /**       * @hibernate .property column="tname"       * @return       */         public String getTname() {        return tname ;     }       public void setTname(String tname) {        this . tname = tname;     } }

 

映射文件：

 

Student.hbm.xml   <? 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 >     < class name = "com.entity.Student" table = "student" >          < id name = "id" column = "id" type = "int" >            < generator class = "native" >               <!--                    To add non XDoclet generator parameters, create a file named                   hibernate-generator-params-Student.xml                   containing the additional parameters and place it in your merge dir.               -->            </ generator >        </ id >          < property name = "sname" type = "java.lang.String" update = "true"            insert = "true" column = "sname" />          < many-to-one name = "teacher" class = "com.entity.Teacher"            cascade = "all" outer-join = "auto" update = "true" insert = "true"            column = "t_id" />          <!--            To add non XDoclet property mappings, create a file named            hibernate-properties-Student.xml            containing the additional properties and place it in your merge dir.        -->       </ class >   </ hibernate-mapping >

 

Teacher.hbm.xml   <? 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 >     < class name = "com.entity.Teacher" table = "teacher" >          < id name = "id" column = "id" type = "int" >            < generator class = "native" >               <!--                    To add non XDoclet generator parameters, create a file named                   hibernate-generator-params-Teacher.xml                   containing the additional parameters and place it in your merge dir.               -->            </ generator >        </ id >          < set name = "students" lazy = "false" inverse = "true" cascade = "all"            sort = "unsorted" >              < key column = "t_id" ></ key >              < one-to-many class = "com.entity.Student" />          </ set >          < property name = "tname" type = "java.lang.String" update = "true"            insert = "true" column = "tname" />          <!--            To add non XDoclet property mappings, create a file named            hibernate-properties-Teacher.xml            containing the additional properties and place it in your merge dir.        -->       </ class >   </ hibernate-mapping >