关联关系

一对一单向外键关联
(学生卡表里有“studentId”字段)

public class Student {
	private int id;
	private String name;
}

public class StuIdCard {
	private int id;
	private String num;
         @OneToOne
	@JoinColumn(name="studentId")
	private Student student;
}

<hibernate-mapping>
	<class name="com.Student" dynamic-update="true">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name"/>
    </class>
</hibernate-mapping>

<hibernate-mapping>
	<class name="com.StuIdCard">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="num"/>
		<many-to-one name="student" column="studentId" unique="true"></many-to-one>
    </class>
</hibernate-mapping>

一对一双外键关联
(学生卡表里有“studentId”字段)

<hibernate-mapping>
	<class name="com.Student" dynamic-update="true">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name"/>
		<one-to-one name="stuIdCard" property-ref="student"></one-to-one>
    </class>
</hibernate-mapping>

学生类添加

@OneToOne(mappedBy="student")
private StuIdCard stuIdCard;

多对一关联

public class User {
	private int id;
	private String name;
	@ManyToOne
	private Group group;
}

public class Group {
	private int id;
	private String name;
}

<hibernate-mapping>
	<class name="com.Group" table="t_group">
		<id name="id">
			<generator class="native"/>
		</id>		
		<property name="name"/>		
    </class>	
</hibernate-mapping>

<hibernate-mapping>
	<class name="com.User" table="t_user">
		<id name="id">
			<generator class="native"/>
		</id>		
		<property name="name"/>
		<many-to-one name="group" column="groupId" />
    </class>	
</hibernate-mapping>

一对多关联

public class Group {
	private int id;
	private String name;
         @OneToMany
	@JoinColumn(name="groupId")
	private Set<User> users = new HashSet<User>();
}

public class User {
	private int id;
	private String name;
}

<hibernate-mapping>
	<class name="com.Group" table="t_group">
		<id name="id">
			<generator class="native"></generator>
		</id>		
		<property name="name"/>
		<set name="users">
			<key column="groupId"></key>
			<one-to-many class="com.User"/>
		</set>
    </class>
</hibernate-mapping>

<hibernate-mapping>
	<class name="com.User" table="t_user">
		<id name="id">
			<generator class="native"></generator>
		</id>		
		<property name="name"></property>		
    </class>	
</hibernate-mapping>

一对多多对一关联

public class Group {
	private int id;
	private String name;
         @OneToMany(mappedBy="group")
	private Set<User> users = new HashSet<User>();
}

public class User {
	private int id;
	private String name;
	@ManyToOne
	private Group group;
}

<hibernate-mapping>
	<class name="com.Group" table="t_group">
		<id name="id">
			<generator class="native"></generator>
		</id>
		<property name="name"></property>
		<set name="users">
			<key column="groupId"></key>
			<one-to-many class="com.User"/>
		</set>
    </class>
</hibernate-mapping>

<hibernate-mapping>
	<class name="com.User" table="t_user">
		<id name="id">
			<generator class="native"></generator>
		</id>		
		<property name="name"></property>
		<many-to-one name="group" column="groupId"></many-to-one>
    </class>	
</hibernate-mapping>

多对多单向

public class Student {
	private int id;
	private String name;
}

public class Teacher {
	private int id;
	private String name;
	@ManyToMany
	@JoinTable(name="t_s",
		joinColumns={@JoinColumn(name="teacher_id")},
		inverseJoinColumns={@JoinColumn(name="student_id")}
		)
	private Set<Student> students = new HashSet<Student>();
}

<hibernate-mapping>
	<class name="com.Student">
		<id name="id">
			<generator class="native"></generator>
		</id>
		<property name="name"></property>
    </class>
</hibernate-mapping>

<hibernate-mapping>
	<class name="com.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.Student" column="student_id"/>
		</set>
    </class>
</hibernate-mapping>

多对多两向关联

public class Student {
	private int id;
	private String name;
	@ManyToMany(mappedBy="students")
	private Set<Teacher> teachers = new HashSet<Teacher>();
}

public class Teacher {
	private int id;
	private String name;
	@ManyToMany
	@JoinTable(name="t_s",
		joinColumns={@JoinColumn(name="teacher_id")},
		inverseJoinColumns={@JoinColumn(name="student_id")}
		)
	private Set<Student> students = new HashSet<Student>();
}

<hibernate-mapping>
	<class name="com.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="comTeacher" column="teacher_id"/>
		</set>
    </class>
</hibernate-mapping>

<hibernate-mapping>
	<class name="com.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.Student" column="student_id"/>
		</set>
    </class>
</hibernate-mapping>