Hibernate注解（一）

Hibernate注解的分类：

（1）类级别的注解：@Entity、@Table、@Embeddable（嵌入类）

（2）属性级别的注解：@Id、@SequenceGenerator、@GeneratedValue、@Column、@Embedded、@EmbeddedId、@Lob、@Version、@Basic、@Transient

（3）映射级别的注解

 

（一）类级别的注解：

1.1 @Entity：映射实体类————》@Entity(name = "tableName")

 name：可选，对应数据中的一个表。若表明与尸体类名相同，则可以省略。使用@Entity时必须指定实体类的主键属性。

1.2 @Table：@Table(name = "",catelog="",schema="")

@Entity配合使用，只能标注在实体的class定义处，表示实体对应的数据库表的信息。

name:可选，映射表的名称，默认表明和实体名称一致，只有在不一致的情况下才需要指定表明。

catalog：可选，便是Catalog名称，默认为Catalog(“”)；

schema：可选，表示Schema名称，默认为Schema("")。

1.3 @Embeddable：@Embeddable(name = "",catelog="",schema="")

@Embeddable表示一个非Entity类可以嵌入到另一个Entity类中作为属性而存在的。

例子：整个demo结构如下

代码：

首先配置文件hibernate.cfg.xml：

 1 <?xml version='1.0' encoding='utf-8'?>
 2 <!DOCTYPE hibernate-configuration PUBLIC
 3 "-//Hibernate/Hibernate Configuration DTD//EN"
 4 "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
 5  
 6 <hibernate-configuration>
 7     <session-factory>
 8        <property name="connection.username">root</property>
 9        <property name="connection.password">mysql</property>
10        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
11        <property name="connection.url">jdbc:mysql:///hibernate?useUnicode=true&amp;characterEncoding=UTF-8</property>
12        
13        <!-- 配置数据的库的前缀 -->
14        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
15            
16            <!-- 
17                是否把Hibernate运行时的SQL语句输出到控制台，编码阶段便于测试
18             -->
19            <property name="show_sql">true</property>
20            <!-- 
21                输出到控制台的SQL语句是否进行排版，便于阅读。建议设置true
22             -->
23            <property name="format_sql">true</property>
24            <!-- 
25                可以到帮助由java代码生成数据库脚本，进而生辰具体的表结构。
26                create|update|create-drop|validate
27             -->
28            <property name="hbm2ddl.auto">create</property>
29            
30            <mapping class="com.entity.Student"/>
31        <!--     <mapping class="com.entity.StudentA"/> -->
32     </session-factory>
33  
34 </hibernate-configuration>
View Code

测试@Entity和@Table注解的相关类：

实体Students：

 1 package com.entity;
 2 
 3 import java.util.Date;
 4 
 5 import javax.persistence.Entity;
 6 import javax.persistence.Id;
 7 import javax.persistence.Table;
 8 
 9 /** 
10  * 学生实体类
11  * 
12  * @Table(name="",catalog="",schema=""),mysql不支持catalog属性，
13  * 这里的name属性和@Enity的name属性作用是一样的都是给表起一个名字
14  *
15  */
16 @Entity//(name = "t_students")
17 @Table(name="t_students",schema="hibernate")
18 public class Students {
19     
20     
21     private int sid;//学号
22     private String sname;//姓名
23     private String gender;//出生日期
24     private Date birthday;//出生日期
25     private String major;//专业
26     private String address;//地址
27     
28     public Students() {
29     }
30 
31     public Students(int sid, String sname, String gender, Date birthday, String major, String address) {
32         this.sid = sid;
33         this.sname = sname;
34         this.gender = gender;
35         this.birthday = birthday;
36         this.major = major;
37         this.address = address;
38     }
39 
40     @Id
41     public int getSid() {
42         return sid;
43     }
44 
45     public void setSid(int sid) {
46         this.sid = sid;
47     }
48 
49     public String getSname() {
50         return sname;
51     }
52 
53     public void setSname(String sname) {
54         this.sname = sname;
55     }
56 
57     public String getGender() {
58         return gender;
59     }
60 
61     public void setGender(String gender) {
62         this.gender = gender;
63     }
64 
65     public Date getBirthday() {
66         return birthday;
67     }
68 
69     public void setBirthday(Date birthday) {
70         this.birthday = birthday;
71     }
72 
73     public String getMajor() {
74         return major;
75     }
76 
77     public void setMajor(String major) {
78         this.major = major;
79     }
80 
81     public String getAddress() {
82         return address;
83     }
84 
85     public void setAddress(String address) {
86         this.address = address;
87     }
88     
89     
90     
91     
92     
93 }
View Code

测试@Embeddedable注解的相关代码（这里注意hibernate.cfg.xml文件中的<mapping class="com.entity.StudentA">）：

实体StudentA:

 1 package com.entity;
 2 
 3 import java.util.Date;
 4 
 5 import javax.persistence.Entity;
 6 import javax.persistence.Id;
 7 import javax.persistence.Table;
 8 
 9 /** 
10  * 学生实体类
11  * 
12  * @Table(name="",catalog="",schema=""),mysql不支持catalog属性，
13  * 这里的name属性和@Enity的name属性作用是一样的都是给表起一个名字
14  *
15  */
16 @Entity//(name = "t_students")
17 @Table(name="t_students",schema="hibernate")
18 public class StudentA {
19     
20     private int sid;//学号
21     private String sname;//姓名
22     private String gender;//出生日期
23     private Date birthday;//出生日期
24     private String major;//专业
25     private Address add;//地址
26     
27     public StudentA() {
28     }
29 
30     public StudentA(int sid, String sname, String gender, Date birthday, String major, Address add) {
31         this.sid = sid;
32         this.sname = sname;
33         this.gender = gender;
34         this.birthday = birthday;
35         this.major = major;
36         this.add = add;
37     }
38 
39     @Id
40     public int getSid() {
41         return sid;
42     }
43 
44     public void setSid(int sid) {
45         this.sid = sid;
46     }
47 
48     public String getSname() {
49         return sname;
50     }
51 
52     public void setSname(String sname) {
53         this.sname = sname;
54     }
55 
56     public String getGender() {
57         return gender;
58     }
59 
60     public void setGender(String gender) {
61         this.gender = gender;
62     }
63 
64     public Date getBirthday() {
65         return birthday;
66     }
67 
68     public void setBirthday(Date birthday) {
69         this.birthday = birthday;
70     }
71 
72     public String getMajor() {
73         return major;
74     }
75 
76     public void setMajor(String major) {
77         this.major = major;
78     }
79 
80     public Address getAdd() {
81         return add;
82     }
83 
84     public void setAdd(Address address) {
85         this.add = address;
86     }
87     
88     
89     
90     
91     
92     
93     
94 }
View Coded

地址实体Address

 1 package com.entity;
 2 
 3 import javax.persistence.Embeddable;
 4 
 5 /*地址类*/
 6 
 7 @Embeddable /*表示嵌入类，这个类的对象在另一个实体类中充当属性*/
 8 public class Address {
 9     
10     private String postCode;//邮编
11     private String address;//地址
12     private String phone;//联系电话
13     
14     public Address() {
15     }
16     
17     public String getPostCode() {
18         return postCode;
19     }
20     public void setPostCode(String postCode) {
21         this.postCode = postCode;
22     }
23     public String getAddress() {
24         return address;
25     }
26     public void setAddress(String address) {
27         this.address = address;
28     }
29     public String getPhone() {
30         return phone;
31     }
32     public void setPhone(String phone) {
33         this.phone = phone;
34     }
35     
36     
37     
38     
39     
40 }
View Code

测试用例：

 1 package com.entity;
 2 
 3 import org.hibernate.SessionFactory;
 4 import org.hibernate.cfg.Configuration;
 5 import org.hibernate.service.ServiceRegistry;
 6 import org.hibernate.service.ServiceRegistryBuilder;
 7 import org.hibernate.tool.hbm2ddl.SchemaExport;
 8 import org.junit.Test;
 9 
10 public class TestStudents {
11     
12     @Test
13     public void testShemaExport(){
14         //创建hibernate配置对象
15         Configuration config = new Configuration().configure();
16         
17         //创建服务注册对象
18         ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
19         
20         //生成sessionFactory
21         SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
22         
23         SchemaExport export = new SchemaExport(config);
24         
25         export.create(true,true);
26         
27         
28     }
29 }
View Code

以上是类级别的注解测试，注意一定要在Student加上@Id属性注解表示主键，否则报错。

 

posted @ 2018-04-12 22:45  花雪依蒿  阅读(125)  评论(0)  编辑  收藏  举报