Hibernate 学习札记（二）――关系映射 _Web前端

Hibernate 学习笔记（二）――关系映射

一、涉及的两张表。

1、员工表（序号、员工编号、姓名、密码、部门）??????????????

???????????????????????????? ??? tbl_employee（nativeId,employeeId,employeeName,password,department）

2、部门表（序号、部门编号、部门名、部门信息、部门成员）

????????????????????????????? tbl_department（nativeId,departmentId,departmentName,departmentinfo,employeeList）

注：序号标识唯一性，这里采用native生成方式。

二、基本类。

1、Employee.java

public class Employee {
 
 private int nativeId;
 private String employeeId;
 private String employeeName;
 private String password;
 private Department department;

   getters and setters...

}

2、Department.java

public class Department {

 private int nativeId;
 private String departmentId;
 private String departmentName;
 private String departmentinfo;
 private Set<Employee>employeeList;

     getters and setters...

}

?注：private Set<Employee>employeeList;采用了Set 而非ArrayList。

三、Hibernate的映射配置(*.hbm.xml)。?

为看得清楚，将其配置文件分开。

1、Employee.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 package="wuyechun.studymvc.model">
 <class name="Employee" table="tbl_employee">
         <id name="nativeId">
                <generator class="native"></generator>
       </id>
       <property name="employeeId"></property>
       <property name="employeeName"></property>
       <property name="password"></property>
       <many-to-one name="department" column="departmentId" cascade="save-update"></many-to-one>
  </class>
</hibernate-mapping>

?2、Department.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 package="wuyechun.studymvc.model">
 <class name="Department" table="tbl_department">
          <id name="nativeId">
                <generator class="native"></generator>
         </id>
         <property name="departmentId"></property>
         <property name="departmentName"></property>
         <property name="departmentinfo"></property>
        <set name="employeeList" >
              <key column="departmentId"></key>
              <one-to-many class="Employee"/>
        </set>
  </class>
</hibernate-mapping>

?以上为基本类和数据库的映射文件，注意 many-to-one? 和 one-to-many 的配置。如不指定column属性（数据库字段名），默认为class属性名和数据库字段名一样，也可另指定columu属性。

四、自动生成的表结构。

1、tbl_employee

2、tbl_department

注：只有tbl_employee表中含有 departmentId 字段标示两张表的映射关系。

ps:仅作记录，方便自己翻阅。如果对你有所帮助，不甚荣幸。