创建持久化和映射文件并配置单向一对多关系

一 Grade

package com.imooc.entity;

import java.io.Serializable;

import java.util.HashSet;

import java.util.Set;

public class Grade implements Serializable {

    private int gid;

    private String gname;

    private String gdesc;

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

    public int getGid() {

        return gid;

    }

    public void setGid(int gid) {

        this.gid = gid;

    }

    public String getGname() {

        return gname;

    }

    public void setGname(String gname) {

        this.gname = gname;

    }

    public String getGdesc() {

        return gdesc;

    }

    public void setGdesc(String gdesc) {

        this.gdesc = gdesc;

    }

    public Grade() {

        super();

    }

    public Set<Student> getStudents() {

        return students;

    }

    public void setStudents(Set<Student> students) {

        this.students = students;

    }

    public Grade(int gid, String gname, String gdesc) {

        super();

        this.gid = gid;

        this.gname = gname;

        this.gdesc = gdesc;

    }

    public Grade(String gname, String gdesc) {

        super();

        this.gname = gname;

        this.gdesc = gdesc;

    }

}

 

 

二 Student

package com.imooc.entity;

 

import java.io.Serializable;

 

public class Student implements Serializable {

        private int sid;

        private String sname;

        private String sex;

 

        public int getSid() {

                return sid;

        }

 

        public void setSid(int sid) {

                this.sid = sid;

        }

 

        public String getSname() {

                return sname;

        }

 

        public void setSname(String sname) {

                this.sname = sname;

        }

 

        public String getSex() {

                return sex;

        }

 

        public void setSex(String sex) {

                this.sex = sex;

        }

 

        public Student() {

                super();

        }

 

        public Student(String sname, String sex) {

                super();

                this.sname = sname;

                this.sex = sex;

        }

 

}

 

三 Grade.hbm.xml

<?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>

        <class name="com.imooc.entity.Grade" table="grade">

                <id name="gid" column="gid" type="java.lang.Integer">

                        <generator class="increment"></generator>

                </id>

                <property name="gname" type="java.lang.String">

                        <column name="gname" length="20" not-null="true"></column>

                </property>

                <property name="gdesc">

                        <column name="gdesc"></column>

                </property>

                <!-- 配置一对多关联关系 -->

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

                        <key column="gid"></key>

                        <one-to-many class="com.imooc.entity.Student"/>

                </set>

        </class>

</hibernate-mapping>

 

四 Student.hbm.xml

<?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>

        <class name="com.imooc.entity.Student" table="student">

                <id name="sid" column="sid" type="java.lang.Integer">

                        <generator class="increment"></generator>

                </id>

                <property name="sname" type="java.lang.String">

                        <column name="sname" length="20" not-null="true"></column>

                </property>

                <property name="sex">

                        <column name="sex"></column>

                </property>

        </class>

</hibernate-mapping>

 

五 hibernate.cfg.xml

<!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>

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

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

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

        <property name="hibernate.connection.password">root</property>

        <property name="hibernate.connection.url">

                <![CDATA[

                        jdbc:mysql://localhost:3306/imooc?useUnicode=true&characterEncoding=utf8

                ]]>

        </property>

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

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

   

        <!-- 指定映射文件的路径 -->

        <mapping resource="com/imooc/entity/Grade.hbm.xml"/>

        <mapping resource="com/imooc/entity/Student.hbm.xml"/>

    </session-factory>

</hibernate-configuration>

 

六 set元素的常用属性