Hibernate注解配置

1.注解方式：

注解的方式与xml很很多类似：

首先是需要在pom文件中加入4个jar包：

 1 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 2   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
 3   <modelVersion>4.0.0</modelVersion>
 4   <groupId>cn.yunhe</groupId>
 5   <artifactId>hibernate3</artifactId>
 6   <packaging>war</packaging>
 7   <version>1.0-SNAPSHOT</version>
 8   <name>hibernate3 Maven Webapp</name>
 9   <url>http://maven.apache.org</url>
10   <dependencies>
11     <dependency>
12       <groupId>junit</groupId>
13       <artifactId>junit</artifactId>
14       <version>4.12</version>
15       <scope>test</scope>
16     </dependency>
17 
18     <dependency>
19       <groupId>javax.servlet</groupId>
20       <artifactId>javax.servlet-api</artifactId>
21       <version>3.1.0</version>
22       <scope>provided</scope>
23     </dependency>
24 
25     <dependency>
26       <groupId>mysql</groupId>
27       <artifactId>mysql-connector-java</artifactId>
28       <version>5.1.6</version>
29     </dependency>
30 
31     <dependency>
32       <groupId>org.apache.struts</groupId>
33       <artifactId>struts2-core</artifactId>
34       <version>2.3.31</version>
35     </dependency>
36 
37     <dependency>
38       <groupId>javax.servlet</groupId>
39       <artifactId>jstl</artifactId>
40       <version>1.2</version>
41     </dependency>
42 
43     <dependency>
44       <groupId>org.apache.struts</groupId>
45       <artifactId>struts2-dojo-plugin</artifactId>
46       <version>2.3.16</version>
47     </dependency>
48 
49 
50 <!--以下四个包，缺一不可-->
51     <dependency>
52       <groupId>org.hibernate</groupId>
53       <artifactId>hibernate-core</artifactId>
54       <version>3.5.0-Final</version>
55     </dependency>
56 
57     <dependency>
58       <groupId>org.hibernate</groupId>
59       <artifactId>hibernate-annotations</artifactId>
60       <version>3.5.0-Final</version>
61     </dependency>
62 
63     <dependency>
64       <groupId>org.slf4j</groupId>
65       <artifactId>slf4j-log4j12</artifactId>
66       <version>1.5.8</version>
67     </dependency>
68 
69     <dependency>
70       <groupId>org.javassist</groupId>
71       <artifactId>javassist</artifactId>
72       <version>3.13.0-GA</version>
73     </dependency>
74   </dependencies>
75   <build>
76     <finalName>hibernate3</finalName>
77     <plugins>
78       <plugin>
79         <groupId>org.eclipse.jetty</groupId>
80         <artifactId>jetty-maven-plugin</artifactId>
81         <version>9.3.14.v20161028</version>
82       </plugin>
83     </plugins>
84   </build>
85 </project>

pom.xml

下面是不同的地方：

（1）：hibernate.hbm.xml 文件中把引用：xxx.hbm.xml改为引用实体类：

即把：<mapping resource="com/wsw/hibernate/model/Person.hbm.xml"/>

改为：<mapping class="com.wsw.hibernate.model.Teacher" />

（2）：获取SessionFactory方式发生了变化：

即：由SessionFactory sf = new Configuration().configure().buildSessionFactory()

改为：SessionFactory sf = new AnnotationConfiguration().configure().buildSessionFactory()

（3）：注解方式不需要在xxx.hbm.xml把实体类与表进行映射。而采用在实体类中进行注解。

注意：

（1）：如果实体类属性名与表字段名不一致的时候，要么都注解在属性前，要么都注解在get方法前。不能部分注解在属性前，部分注解在方法前。

（2）：如果实体类属性名与表字段名一致的时候，可以部分注解在属性前，部分注解在方法前。

（3）：如果在实体类中某些属性不注解：（属性和get都不写注解），默认为表字段名与实体类属性名一致。

（4）：如果实体类的某个成员属性不需要存入数据库中，使用@Transient 进行注解就可以了。即类似于：(xxx.hbm.Xml配置中的某些字段不写(就是不需要对这个成员属性进行映射))

（5）：表名称可以在实体类前进行注解。

（6）：所有这些注解在：javax.persistence包下。而不是在hibernate包中。

2.单向一对多、单向多对一、双向多对一

1.实体类配置

 1 package cn.yunhe.entity;
 2 
 3 import javax.persistence.*;
 4 import java.io.Serializable;
 5 
 6 
 7 @Entity
 8 @Table(name = "jd")
 9 public class Jd {//街道
10     private int jdid;
11     private String jdname;
12     private Qx qx;//区县
13 
14     @Id
15     @GeneratedValue
16     @Column(name = "jdid")
17     public int getJdid() {
18         return jdid;
19     }
20 
21     public void setJdid(int jdid) {
22         this.jdid = jdid;
23     }
24 
25     @Column(name = "jdname")
26     public String getJdname() {
27         return jdname;
28     }
29 
30     public void setJdname(String jdname) {
31         this.jdname = jdname;
32     }
33 
34     @ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.LAZY)
35     @JoinColumn(name = "qxid")
36     public Qx getQx() {
37         return qx;
38     }
39 
40     public void setQx(Qx qx) {
41         this.qx = qx;
42     }
43 }

Jd(街道)

 1 package cn.yunhe.entity;
 2 
 3 import javax.persistence.*;
 4 import java.util.HashSet;
 5 import java.util.Set;
 6 
 7 @Entity
 8 @Table(name = "qx")//实体类映射表
 9 public class Qx {//区县
10     private int qxid;
11     private String qxname;
12     private Set<Jd> jds=new HashSet<Jd>();
13 
14     @Id
15     @GeneratedValue
16     @Column(name = "qxid")
17     public int getQxid() {
18         return qxid;
19     }
20 
21     public void setQxid(int qxid) {
22         this.qxid = qxid;
23     }
24 
25     @Column(name = "qxname")
26     public String getQxname() {
27         return qxname;
28     }
29 
30     public void setQxname(String qxname) {
31         this.qxname = qxname;
32     }
33 
34     //@OneToMany(cascade = CascadeType.ALL,fetch = FetchType.LAZY ,mappedBy = "qx")//mappedBy里面写的是对象
35     //@JoinColumn(name ="qxid" ) 双向操作Qx一对多声明可以不需要@JoinColumn，但@OneToMany(...mappedBy="category")
36     public Set<Jd> getJds() {
37         return jds;
38     }
39 
40     public void setJds(Set<Jd> jds) {
41         this.jds = jds;
42     }
43 }

Qx(区县)

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-configuration
 3         PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 4         "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
 5 <hibernate-configuration>
 6     <session-factory>
 7         <property name="hibernate.hbm2ddl.auto" >update</property><!--自动生成数据库表-->
 8         <property name="dialect">org.hibernate.dialect.MySQLDialect</property><!--数据库方言-->
 9         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
10         <property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>
11         <property name="connection.username">root</property>
12         <property name="connection.password">1234</property>
13         <property name="show_sql">true</property><!--显示sql-->
14 
15         <mapping class="cn.yunhe.entity.Qx"/>
16         <mapping class="cn.yunhe.entity.Jd"/>
17     </session-factory>
18 </hibernate-configuration>

hibernate.cfg.xml

2. 测试类

 1 import cn.yunhe.entity.Jd;
 2 import cn.yunhe.entity.Qx;
 3 import org.hibernate.Session;
 4 import org.hibernate.SessionFactory;
 5 import org.hibernate.Transaction;
 6 import org.hibernate.cfg.AnnotationConfiguration;
 7 import org.hibernate.cfg.Configuration;
 8 import org.junit.After;
 9 import org.junit.Before;
10 import org.junit.Test;
11 
12 import java.util.List;
13 import java.util.Set;
14 
15 /**
16  * Created by Administrator on 2017/7/6.
17  */
18 public class Demo {
19     Session session=null;
20     Transaction tr=null;
21 
22     @Before
23     public void setUp(){
24         Configuration config=new AnnotationConfiguration().configure();
25         SessionFactory factory= config.buildSessionFactory();
26         session=factory.openSession();
27         tr=session.beginTransaction();
28     }
29     @Test
30     public void testQuery(){
31         List<Qx> list = session.createQuery("from Qx").list();
32         for (Qx qx : list) {
33             System.out.println(qx.getQxname());
34         }
35     }
36 
37     @Test
38     //单向一对多（使用时注意只能在实体类一的一方建多的一方对象，不能两边都创建）
39     public void testOneToMany(){
40         Qx qx= (Qx) session.get(Qx.class,1);
41         System.out.println(qx.getQxname()+"下的街道有：");
42         Set<Jd> set=qx.getJds();
43         for(Jd jd:set){
44             System.out.println(jd.getJdname());
45         }
46     }
47     @Test
48     //单向多对一 /双向多对一（使用时注意只能在实体类多的一方建一的一方对象，不能两边都创建）
49     public void testManyToOne(){
50         Jd jd= (Jd) session.get(Jd.class,1);
51         System.out.println(jd.getJdname()+"属于");
52         System.out.println(jd.getQx().getQxname());
53     }
54 
55 
56     @After
57     public void tearDowm(){
58         session.close();
59     }
60 }

Demo

3.双向多对多

1.实体类

 1 package cn.yunhe.entity;
 2 
 3 import javax.persistence.*;
 4 import java.util.HashSet;
 5 import java.util.Set;
 6 
 7 @Entity
 8 @Table(name = "student")
 9 public class Student {//学生表
10     private int id;
11     private String name;
12     public Set<Teacher> teachers =new HashSet<Teacher>();//互相建对方的set集合
13 
14     @Id
15     @GeneratedValue
16     @Column(name = "id")
17     public int getId() {
18         return id;
19     }
20 
21     public void setId(int id) {
22         this.id = id;
23     }
24 
25     @Column(name = "name")
26     public String getName() {
27         return name;
28     }
29 
30     public void setName(String name) {
31         this.name = name;
32     }
33 
34     @ManyToMany(cascade = CascadeType.ALL,fetch = FetchType.LAZY)
35     //配置中间表，并将外键对照起来
36     @JoinTable(name = "student_teacher",
37             joinColumns = @JoinColumn(name = "studentid"),
38             inverseJoinColumns = @JoinColumn(name ="teacherid"))
39     public Set<Teacher> getTeachers() {
40         return teachers;
41     }
42 
43     public void setTeachers(Set<Teacher> teachers) {
44         this.teachers = teachers;
45     }
46 }

student

 1 package cn.yunhe.entity;
 2 
 3 import javax.persistence.*;
 4 import java.util.HashSet;
 5 import java.util.Set;
 6 
 7 
 8 @Entity
 9 @Table(name = "teacher")
10 public class Teacher {//教师
11     private  int id;
12     private String name;
13     public Set<Student> students =new HashSet<Student>();//互相建对方的集合
14 
15     @Id
16     @GeneratedValue
17     @Column(name = "id")
18     public int getId() {
19         return id;
20     }
21 
22     public void setId(int id) {
23         this.id = id;
24     }
25 
26     @Column(name = "name")
27     public String getName() {
28         return name;
29     }
30 
31     public void setName(String name) {
32         this.name = name;
33     }
34 
35     @ManyToMany(cascade = CascadeType.ALL,
36                 fetch = FetchType.LAZY,mappedBy = "teachers")
37     public Set<Student> getStudents() {
38         return students;
39     }
40 
41     public void setStudents(Set<Student> students) {
42         this.students = students;
43     }
44 }

teacher

2.测试类

 1 import cn.yunhe.entity.Jd;
 2 import cn.yunhe.entity.Qx;
 3 import cn.yunhe.entity.Student;
 4 import cn.yunhe.entity.Teacher;
 5 import org.hibernate.Session;
 6 import org.hibernate.SessionFactory;
 7 import org.hibernate.Transaction;
 8 import org.hibernate.cfg.AnnotationConfiguration;
 9 import org.hibernate.cfg.Configuration;
10 import org.junit.After;
11 import org.junit.Before;
12 import org.junit.Test;
13 
14 import java.util.List;
15 import java.util.Set;
16 
17 /**
18  * Created by Administrator on 2017/7/6.
19  */
20 public class Demo {
21     Session session=null;
22     Transaction tr=null;
23 
24     @Before
25     public void setUp(){
26         Configuration config=new AnnotationConfiguration().configure();
27         SessionFactory factory= config.buildSessionFactory();
28         session=factory.openSession();
29         tr=session.beginTransaction();
30     }
31 
32 
33     @Test
34     //双向多对多(要有中间表，实体类互相建对方的对象的Set集合)
35     public  void testManyToMany(){
36         //根据学生查老师
37         Student student= (Student) session.get(Student.class,5);
38         System.out.println("学生："+student.getName()+"的老师有：");
39         Set<Teacher> teachers=student.getTeachers();
40         for (Teacher t:teachers){
41             System.out.println(t.getName());
42         }
43 
44         //根据老师查学生
45         Teacher teacher= (Teacher) session.get(Teacher.class,4);
46         System.out.println("老师："+teacher.getName()+"的学生有：");
47         Set<Student> students=teacher.getStudents();
48         for (Student s:students){
49             System.out.println(s.getName());
50         }
51     }
52 
53     @After
54     public void tearDowm(){
55         session.close();
56     }
57 }

Demo

3.主配置文件

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-configuration
 3         PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 4         "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
 5 <hibernate-configuration>
 6     <session-factory>
 7         <property name="hibernate.hbm2ddl.auto" >update</property><!--自动生成数据库表-->
 8         <property name="dialect">org.hibernate.dialect.MySQLDialect</property><!--数据库方言-->
 9         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
10         <property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>
11         <property name="connection.username">root</property>
12         <property name="connection.password">1234</property>
13         <property name="show_sql">true</property><!--显示sql-->
14       
15         <mapping class="cn.yunhe.entity.Student"/>
16         <mapping class="cn.yunhe.entity.Teacher"/>
17 
18     </session-factory>
19 </hibernate-configuration>

hibernate.cfg.xml

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原文地址：https://www.cnblogs.com/liuyingke/p/7134092.html