Java知识点11 Hibernate多对多单向关联（Annotation+XML实现）

2020-12-13 14:42

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标签：单向关联 coding his com 原创自己 teacher driver figure

1、Annotation 注解版

1.1、应用场景（Student-Teacher）：当学生知道有哪些老师教，但是老师不知道自己教哪些学生时，可用单向关联的多对多模式

1.2、创建Teacher类和Student类

 1 package com.shore.model;
 2 
 3 import javax.persistence.Entity;
 4 import javax.persistence.GeneratedValue;
 5 import javax.persistence.GenerationType;
 6 import javax.persistence.Id;
 7 import javax.persistence.Table;
 8 
 9 /**
10  * @author DSHORE/2019-9-22
11  * 多对多，单向关联（注解版）
12  */
13 @Entity
14 @Table(name="anno_teacher")
15 public class Teacher {
16     private Integer id;
17     private String name;
18     private Integer age;
19     
20     @Id
21     @GeneratedValue(strategy=GenerationType.IDENTITY)
22     public Integer getId() {
23         return id;
24     }
25     public void setId(Integer id) {
26         this.id = id;
27     }
28     public String getName() {
29         return name;
30     }
31     public void setName(String name) {
32         this.name = name;
33     }
34     public Integer getAge() {
35         return age;
36     }
37     public void setAge(Integer age) {
38         this.age = age;
39     }
40 }

Student类

 1 package com.shore.model;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 import javax.persistence.Entity;
 7 import javax.persistence.GeneratedValue;
 8 import javax.persistence.GenerationType;
 9 import javax.persistence.Id;
10 import javax.persistence.JoinColumn;
11 import javax.persistence.JoinTable;
12 import javax.persistence.ManyToMany;
13 import javax.persistence.Table;
14 
15 /**
16  * @author DSHORE/2019-9-22
17  * 多对一，单向关联（注解版）
18  */
19 @Entity
20 @Table(name="anno_student") 
21 public class Student {
22     private Integer id;
23     private String number;
24     private Float sum;
25     private Set teachers = new HashSet();
26     
27     @Id
28     @GeneratedValue(strategy=GenerationType.IDENTITY)
29     public Integer getId() {
30         return id;
31     }
32     public void setId(Integer id) {
33         this.id = id;
34     }
35     public String getNumber() {
36         return number;
37     }
38     public void setNumber(String number) {
39         this.number = number;
40     }
41     public Float getSum() {
42         return sum;
43     }
44     public void setSum(Float sum) {
45         this.sum = sum;
46     }
47     
48     /**
49      * name：中间表的表名
50      * joinColumns：当前对象所对应的id
51      * inverseJoinColumns：对方对象所对应的id
52      */
53     @ManyToMany
54     @JoinTable(name="anno_student_teacher",
55                joinColumns=@JoinColumn(name="student_id"),
56                inverseJoinColumns=@JoinColumn(name="teacher_id"))
57     public Set getTeachers() {
58         return teachers;
59     }
60     public void setTeachers(Set teachers) {
61         this.teachers = teachers;
62     }
63 }

1.3、创建hibernate.cfg.xml核心配置文件

 1 xml version=‘1.0‘ encoding=‘utf-8‘?>
 2 DOCTYPE hibernate-configuration PUBLIC
 3         "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 4         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
 5 
 6 hibernate-configuration>
 7     session-factory>
 8         
 9         property name="connection.driver_class">com.mysql.jdbc.Driverproperty>
10         property name="connection.url">jdbc:mysql://localhost:3306/hibernateproperty>
11         property name="connection.username">rootproperty>
12         property name="connection.password">123456property>
13 
14         property name="dialect">org.hibernate.dialect.MySQLDialectproperty>
15         property name="cache.provider_class">org.hibernate.cache.NoCacheProviderproperty>
16         property name="show_sql">trueproperty>
17         property name="hbm2ddl.auto">createproperty>
18 
19         mapping class="com.shore.model.Teacher" />
20         mapping class="com.shore.model.Student" />
21     session-factory>
22 hibernate-configuration>

1.4、开始测试

 1 package com.shore.test;
 2 
 3 import org.hibernate.cfg.AnnotationConfiguration;
 4 import org.hibernate.tool.hbm2ddl.SchemaExport;
 5 import org.junit.Test;
 6 
 7 /**
 8  * @author DSHORE/2019-9-22
 9  *
10  */
11 public class AnnotationTest {
12     @Test
13     public void test() {//简单测试，只创建表，不插入数据
14         new SchemaExport(new AnnotationConfiguration().configure()).create(
15                 false, true);
16     }
17 }

测试结果图：

技术图片

2、XML版的实现

2.1、创建Teacher类和Student类

 1 package com.shore.model;
 2 
 3 /**
 4  * @author DSHORE/2019-9-22
 5  * 多对多，单向关联（xml版）
 6  */
 7 public class Teacher {
 8     private Integer id;
 9     private String name;
10     private Integer age;
11     
12     public Integer getId() {
13         return id;
14     }
15     public void setId(Integer id) {
16         this.id = id;
17     }
18     public String getName() {
19         return name;
20     }
21     public void setName(String name) {
22         this.name = name;
23     }
24     public Integer getAge() {
25         return age;
26     }
27     public void setAge(Integer age) {
28         this.age = age;
29     }
30 }

Student类

 1 package com.shore.model;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 /**
 7  * @author DSHORE/2019-9-22
 8  * 多对一，单向关联（xml版）
 9  */
10 public class Student {
11     private Integer id;
12     private String number;
13     private Float sum;
14     private Set teachers = new HashSet();
15     
16     public Integer getId() {
17         return id;
18     }
19     public void setId(Integer id) {
20         this.id = id;
21     }
22     public String getNumber() {
23         return number;
24     }
25     public void setNumber(String number) {
26         this.number = number;
27     }
28     public Float getSum() {
29         return sum;
30     }
31     public void setSum(Float sum) {
32         this.sum = sum;
33     }
34     public Set getTeachers() {
35         return teachers;
36     }
37     public void setTeachers(Set teachers) {
38         this.teachers = teachers;
39     }
40 }

2.2、创建 Teacher.hbm.xml 配置文件和 Student.hbm.xml 配置文件

 1 xml version="1.0"?>
 2 DOCTYPE hibernate-mapping PUBLIC
 3         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 5         
 6 hibernate-mapping package="com.shore.model">
 7     class name="Teacher" table="xml_teacher">  
 8         id name="id"> 
 9             generator class="native"/>
10         id>
11         property name="name" type="java.lang.String"/>
12         property name="age" type="java.lang.Integer"/>
13     class>
14 hibernate-mapping>

Student.hbm.xml 配置文件

 1 xml version="1.0"?>
 2 DOCTYPE hibernate-mapping PUBLIC
 3         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 5         
 6 hibernate-mapping package="com.shore.model">
 7     class name="Student" table="xml_student">  
 8         id name="id"> 
 9             generator class="native"/>
10         id>
11         property name="number" type="java.lang.String"/>
12         property name="sum" type="java.lang.Float"/>
13         
14         set name="teachers" table="xml_student_teacher">
15             key column="student_id"/> 
16             many-to-many class="com.shore.model.Teacher" column="teacher_id"/> 
17         set>
18     class>
19 hibernate-mapping>

2.3、创建hibernate.cfg.xml 核心配置文件

 1 xml version=‘1.0‘ encoding=‘utf-8‘?>
 2 DOCTYPE hibernate-configuration PUBLIC
 3         "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 4         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
 5 
 6 hibernate-configuration>
 7     session-factory>
 8         
 9         property name="connection.driver_class">com.mysql.jdbc.Driverproperty>
10         property name="connection.url">jdbc:mysql://localhost:3306/hibernateproperty>
11         property name="connection.username">rootproperty>
12         property name="connection.password">123456property>
13 
14         property name="dialect">org.hibernate.dialect.MySQLDialectproperty>
15         property name="cache.provider_class">org.hibernate.cache.NoCacheProviderproperty>
16         property name="show_sql">trueproperty>
17         property name="hbm2ddl.auto">createproperty>
18 
19         
21         mapping resource="com/shore/model/Teacher.hbm.xml" />
22         mapping resource="com/shore/model/Student.hbm.xml" />
23     session-factory>
24 hibernate-configuration>

2.4、开始测试

 1 package com.shore.test;
 2 
 3 import org.hibernate.cfg.Configuration;
 4 import org.hibernate.tool.hbm2ddl.SchemaExport;
 5 import org.junit.Test;
 6 
 7 /**
 8  * @author DSHORE/2019-9-22
 9  *
10  */
11 public class XMLTest {
12     @Test
13     public void test() {//简单测试，只创建表，不插入数据
14                     //xml版，这里用的是Configuration()方法。
15         new SchemaExport(new Configuration().configure()).create(
16                 false, true);
17     }
18 }