Hibernate关联关系配置

蔚落 2022-03-01 13:54 270阅读 0赞

1.单向多对一配置  
基础配置

<property name="connection.driver_class">oracle.jdbc.driver.jdbcDriver</property>
    		<property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>
    		<property name="connection.username">scott</property>
    		<property name="connection.password">tiger</property>
    
    		
    		<property name="dialect">org.hibernate.dialect.OracleDialect</property>
    		
    		<property name="format_sql">true</property>
    		<property name="show_sql">true</property>
    		
    		<property name="hbm2ddl.auto">update</property>
    		
    		<mapping name="hbm/Student.hbm.xml"></mapping>
    		<mapping name="hbm/Teacher.hbm.xml"></mapping>

One 配置对象

clas Student
    	private int sid;
    	private String sname;
    	private Teacher teacher;

Many

class Student
    	private int tid;
    	private String tname;
    	private Student student;

Mapping配置文件

many:

<hibernate-mapping package="com.hxzy.manyone">
    
    	
    	<class name="com.hxzy.manytoone.entity.Teacher" table="teacher">
    
    		
    		<id name="tid" column="tid">
    			<generator class="sequence">
    				<param name="sequence">
    					seq_teacher
    				</param>
    			</generator>
    		</id>
    
    		
    		<property name="name" not-null="true"></property>
    		
    		<many-to-one name="Student" class="com.hxzy.manytoone.entity.Student" column="s_id" cascade="save-update">
    		</many-to-one>
    		
    		
    		
    	</class>
    </hibernate-mapping>

one:

<hibernate-mapping package="com.hxzy.manyone">
    	<class name="com.hxzy.manytoone.entity.Student" table="student">
    		<id name="sid" column="sid">
    			<generator class="sequence">
    			    <param name="sequence">
    			        seq_student
    			    </param>
    			</generator>
    		</id>
    		<property name="name" not-null="true"></property>
    	</class>
    </hibernate-mapping>

dao层

Session session = null;
    	
    	/**
    	 * 获取session
    	 * */
    	public Session getSession() {
    		Configuration cfg = new Configuration().configure();
    		SessionFactory sessionFactory= cfg.buildSessionFactory();
    		Session session = sessionFactory.openSession();
    		return session;
    	}
    	
    	public void addTeacher(Teacher teacher) {
    		session = getSession();
    		Transaction ts = session.beginTransaction();
    		try {
    			session.save(teacher);//存入老湿信息
    			ts.commit();//提交事务
    		}catch(Exception e) {
    			e.printStackTrace();
    			ts.rollback();//报错则回滚
    		}finally {
    			session.close();
    		}
    	}
    	测试代码

@Test
    	public void test1() {
    		DaoImpl daoImpl = new DaoImpl();
    		Teacher t1 = new Teacher();
    		Teacher t2 = new Teacher();
    		Student s1 = new Student();
    		s1.setSname("gz1");
    		t1.setTname("gt1");
    		t1.setStudent(s1);
    		t2.setTname("gt2");
    		t2.setStudent(s1);
    		daoImpl.addObject(s1);
    		daoImpl.addObject(t1);
    		daoImpl.addObject(t2);
    	}

创建的库  
![百度百度百度][20190328175216512.png]  
![百度百度百度][2019032817530988.png]  
![百度百度百度][2019032817532749.png]  
框架在数据库中的操作  
create table Teacher(Id bigint not null primary key,sid bigint not null )//在teacher中创建主键tid，外键sid并和student中的sid关联  
create table Student ( sid bigint not null primary key )//创建sid主键  
2.单向一对一配置  
基于外键关联的单向一对一关联和单向多对一关联几乎是一样的。唯一的不同就是单向一对一关  
联中的外键字段具有唯一性约束。  
xml中其他不变仅在多对一节点添加unique=“true”

<many-to-one name="student"
    			class="com.hxzy.manyone.entity.Student" unique="true"
    			column="stu_id" not-null="true" />

3.基于外键关联的单向一对多关联是一种很少见的情况，并不推荐使用。  
对于这种关联关系最好使用连接表。

4.使用连接表的一对多  
基于连接表的单向一对多关联 应该优先被采用。请注意，通过指定unique=“true”，我们可以把多  
样性从多对多改变为一对多。

student：
    <class name="com.hxzy.manymany.entity.Student" table="student">
    		<id name="sid" column="sid">
    			<generator class="sequence">
    				<param name="seuqence">seq_student</param>
    			</generator>
    		</id>
    		<property name="sname" not-null="true"></property>
    	</class>
    	
    	
    	teacher：
    	
    	<class name="com.hxzy.manymany.entity.Teacher" table="teacher">
    		<id name="tid" column="tid">
    			<generator class="sequence">
    				<param name="sequence">seq_teacher</param>
    			</generator>
    		</id>
    		<property name="tname" not-null="true"></property>
    		
    		
    		<set name="set" table="teacher_student">
    			<key column="tid" />
    			<many-to-many column="sid" unique="true"
    				class="com.hxzy.manymany.entity.Student" />
    		</set>
    	</class>

teacher类：

private int tid;
    	private String tname;
    	private Set<Student> set = new HashSet<Student>();

student类

private int sid;
    	private String sname;
    	private Teacher teacher;

test：

@Test
    	public void test1() {
    		DaoImpl daoImpl = new DaoImpl();
    		Teacher t1 = new Teacher();
    		Set<Student> set = new HashSet<Student>();
    		Student s1 = new Student();
    		Student s2 = new Student();
    		s1.setSname("gz1");
    		s2.setSname("gz2");
    		set.add(s1);
    		set.add(s2);
    		t1.setTname("gt1");
    		t1.setSet(set); 
    		daoImpl.addObject(s1);
    		daoImpl.addObject(s2);
    		daoImpl.addObject(t1);
    	}

最终形成的数据库结构  
![百度百度百度述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L29MZW5nWXVlSHVu_size_16_color_FFFFFF_t_70]![百度百度百度][20190328190345258.png]  
![百度百度百度][20190328190358179.png]  
![百度百度百度][20190328190414800.png]  
可以看到，（tid，sid）作为连接表的主键，sid和tid为连接表的外键，从而将student的主键sid化作了teacher的外键

.多对多  
单向多对多

<class name="com.hxzy.manyone.entity.Teacher" table="teacher">
    
    		
    		<id name="id" column="id">
    			<generator class="sequence">
    				
    				<param name="sequence">
    					seq_teacher
    				</param>
    			</generator>
    		</id>
    
    		
    		<property name="name" not-null="true"></property>
    		
            
    		<set name="Student" table="teacher_sutdent">
    			<key column="id" />
    			<many-to-many column="stu_id"
    				class="com.hxzy.manyone.entity.Student" />
    		</set>
    	</class>

测试代码

@Test
    	public void Test1() {
    		DaoImpl daoImpl = new DaoImpl();
    		Student student1 = new Student();
    		Student student2 = new Student();
    		Teacher teacher1 = new Teacher();
    //		Teacher teacher2 = new Teacher();
    		Set<Student> set1 = new HashSet<Student>();
    		student1.setName("a");
    		student2.setName("b");
    		teacher1.setName("gz");
    	//	teacher2.setName("gz1");
    		set1.add(student1);
    		set1.add(student2);
    		teacher1.setSet(set1);
    		daoImpl.addObject(student1);
    		daoImpl.addObject(student2);
    		daoImpl.addObject(teacher1);
    	//	daoImpl.addTeacher(teacher2);

效果如下  
生成一个新表t\_s，其主键为stu\_id，外键为（id（来自teacher）,stu\_id），与student中的外键stu\_id关联,与teacher中的外键stu\_id关联  
![百度百度百度][20190323093730214.png]  
![百度百度百度][20190323104456408.png]  
teacher表  
![百度百度百度][20190323104609765.png]  
![百度百度百度][2019032310463726.png]  
student表  
![百度百度百度][20190323104940777.png]  
![百度百度百度][20190323104959983.png]  
5.双向关联  
双向多对一关联 是最常见的关联关系

<class name="com.hxzy.manymany.entity.Teacher" table="teacher">
    		<id name="tid" column="tid">
    			<generator class="sequence">
    				<param name="sequence">seq_teacher</param>
    			</generator>
    		</id>
    		<property name="tname" not-null="true"></property>
    		
    		
    		<many-to-one name="student"
    			class="com.hxzy.manymany.entity.Student" column="sid"
    			cascade="save-update" />
    
    </class>

<class name="com.hxzy.manymany.entity.Student" table="student">
    		<id name="sid" column="sid">
    			<generator class="sequence">
    				<param name="seuqence">seq_student</param>
    			</generator>
    		</id>
    		<property name="sname" not-null="true"></property>
    
    		
    		<set name="set" inverse="true">
    			<key column="sid" />
    			<one-to-many class="com.hxzy.manymany.entity.Teacher" />
    		</set>
    		
    </class>

Class Many:

public class Teacher {
    	private int tid;
    	private String tname;
    	private Student student;

Class One:

public class Student {
    	private int sid;
    	private String sname;
    	Set<Teacher> set = new HashSet<Teacher>();

Test:

public class Test1 {
    	@Test
    	public void test1() {
    		DaoImpl daoImpl = new DaoImpl();
    		Teacher t1 = new Teacher();
    		Teacher t2 = new Teacher();
    		Set<Teacher> set1 = new HashSet<Teacher>();
    		Student s1 = new Student();
    		t1.setTname("gt1");
    		t2.setTname("gt2");
    		set1.add(t1);
    		set1.add(t2);
    		s1.setSname("gz1");
    		s1.setSet(set1);
    		daoImpl.addObject(t1);
    		daoImpl.addObject(t2);
    		daoImpl.addObject(s1);	
    	}
    }

生成的数据库结构  
![百度百度百度][20190331172153585.png]  
![百度百度百度][20190331172407556.png]  
双向一对一关联基于外键关联也很常见

teacher：
    <class name="com.hxzy.manymany.entity.Teacher" table="teacher">
    
    		<id name="tid" column="tid">
    			<generator class="sequence">
    				<param name="sequence">seq_teacher</param>
    			</generator>
    		</id>
    		<property name="tname" not-null="true"></property>
    		
    		
    		<many-to-one name="student" column="sid"
    			class="com.hxzy.manymany.entity.Student" unique="true"
    			not-null="true" />
    	</class>

student:
    <class name="com.hxzy.manymany.entity.Student" table="student">
    		<id name="sid" column="sid">
    			<generator class="sequence">
    				<param name="seuqence">seq_student</param>
    			</generator>
    		</id>
    		<property name="sname" not-null="true"></property>
    
    		
    		<one-to-one nam="teacher" property-ref="student"
    			class="com.hxzy.manymany.entity.Teacher" />
    
    	</class>

teacher:
    public class Teacher {
    	private int tid;
    	private String tname;
    	private Student student;
    	}
    	
    student:
    public class Student {
    	private int sid;
    	private String sname;
    	private Teacher teacher;

test:
    @Test
    	public void test1() {
    		DaoImpl daoImpl = new DaoImpl();
    		Teacher t1 = new Teacher();
    		Teacher t2 = new Teacher();
    		Student s1 = new Student();
    		Student s2 = new Student();
    		t1.setTname("gt1");
    		t2.setTname("gt2");
    		s1.setSname("gz1");
    		s2.setSname("gz2");
    		t1.setStudent(s1);
    		t2.setStudent(s2);
    		daoImpl.addObject(s1);
    		daoImpl.addObject(s2);
    		daoImpl.addObject(t1);
    		daoImpl.addObject(t2);
    	}

基于主键关联的一对一关联则需要使用特定的id生成器

teachet:
    <class name="com.hxzy.manymany.entity.Teacher" table="teacher">
    		<id name="tid" column="tid">
    		<generator class="sequence">
    		<param name="sequence">seq_teacher</param>
    		</generator>
    		</id>
    
    		<property name="tname" not-null="true"></property>
    
    		
    		<one-to-one name="student"
    			class="com.hxzy.manymany.entity.Student" />
    </class>

student:
    <class name="com.hxzy.manymany.entity.Student" table="student">
    		
    		<id name="sid" column="tid">
    			<generator class="foreign">
    				<param name="property">teacher</param>
    			</generator>
    		</id>
    		<property name="sname" not-null="true"></property>
    
    		
    		<one-to-one name="teacher"
    			class="com.hxzy.manymany.entity.Teacher" constrained="true" />
    </class>

test:

@Test
    	public void test1() {
    		DaoImpl daoImpl = new DaoImpl();
    		Teacher t1 = new Teacher();
    		Teacher t2 = new Teacher();
    		Student s1 = new Student();
    		Student s2 = new Student();
    		t1.setTname("gt1");
    		t2.setTname("gt2");
    		s1.setSname("gz1");
    		s2.setSname("gz2");
    		s1.setTeacher(t1);//引用他人主键的一方中set他人属性
    		s2.setTeacher(t2);
    		daoImpl.addObject(t1);
    		daoImpl.addObject(t2);
    		daoImpl.addObject(s1);
    		daoImpl.addObject(s2);
    			}

生成的数据库如下：  
![百度百度百度][2019040110240289.png]  
![百度百度百度][20190401102425391.png]  
![百度百度百度][20190401102444689.png]

[20190328175216512.png]: /images/20220301/50155487b94f4b10a221bd2315d09580.png
[2019032817530988.png]: /images/20220301/e5ce7e1211f243f7a97bb1c554adce7a.png
[2019032817532749.png]: /images/20220301/d983018fa65b41f5bb2a5ab6a2da9f92.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L29MZW5nWXVlSHVu_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20190328171047609.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L29MZW5nWXVlSHVu,size_16,color_FFFFFF,t_70
[20190328190345258.png]: /images/20220301/1ebd6d3aa74d46e6b06afdffc6af463f.png
[20190328190358179.png]: /images/20220301/8ca34435cdca41aca0e49cb10dbecf60.png
[20190328190414800.png]: /images/20220301/57c933451b1944c4af81c1c1ffd8e684.png
[20190323093730214.png]: /images/20220301/de17aff7e76a458da8fc3bd64d2a65a8.png
[20190323104456408.png]: /images/20220301/ed2b9a7659ff4395b2d436b719f6322b.png
[20190323104609765.png]: /images/20220301/b13c9a13ba3e4fee866f90b0df84f3cf.png
[2019032310463726.png]: /images/20220301/f3781db7832d4a76add885d3ae775a42.png
[20190323104940777.png]: /images/20220301/98d95650f5b24c878ddb99752a00394e.png
[20190323104959983.png]: /images/20220301/029fbdcf38eb41b7a977aeafec39152e.png
[20190331172153585.png]: /images/20220301/11133e58e243472ea388353f6b12ff74.png
[20190331172407556.png]: /images/20220301/a41d71b7d18342d2b3c5d827d0b8d275.png
[2019040110240289.png]: /images/20220301/27102ee9ba9e4368b9315825857dc1ed.png
[20190401102425391.png]: /images/20220301/c5ae5f7427904528824f6c6ab45ed374.png
[20190401102444689.png]: /images/20220301/0b278d04ebae4379943b8e6b3d9f242b.png