Hibernate的@GeneratedValue注解

1.新建一个java project项目，里面新建一个lib文件夹，lib文件夹里面放置要用的一些jar文件，然后全部选中导入到项目中去。整体的框架如下图所示：

2.Students.java里面的代码如下图所示：

package entity;import java.io.Serializable;import java.util.Date;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name = "t_students", schema = "hibernate")public class Students implements Serializable {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int sid;private String sname;private String gender;private Date birthday;private String major;private Address add;public Students() {}public Students(int sid, String sname, String gender, Date birthday,String major, Address add) {this.sid = sid;this.sname = sname;this.gender = gender;this.birthday = birthday;this.major = major;this.add = add;}public int getSid() {return sid;}public void setSid(int sid) {this.sid = sid;}public String getSname() {return sname;}public void setSname(String sname) {this.sname = sname;}public String getGender() {return gender;}public void setGender(String gender) {this.gender = gender;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}public String getMajor() {return major;}public void setMajor(String major) {this.major = major;}public Address getAdd() {return add;}public void setAdd(Address add) {this.add = add;}}

3.Address.java里面的代码：

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1. package entity;  
2.   
3. import javax.persistence.Embeddable;  
4.   
5. @Embeddable  
6. public class Address {  
7.   
8.     private String postCode;  
9.     private String address;  
10.     private String phone;  
11.   
12.     public Address() {  
13.   
14.     }  
15.   
16.     public String getPostCode() {  
17.         return postCode;  
18.     }  
19.   
20.     public void setPostCode(String postCode) {  
21.         this.postCode = postCode;  
22.     }  
23.   
24.     public String getAddress() {  
25.         return address;  
26.     }  
27.   
28.     public void setAddress(String address) {  
29.         this.address = address;  
30.     }  
31.   
32.     public String getPhone() {  
33.         return phone;  
34.     }  
35.   
36.     public void setPhone(String phone) {  
37.         this.phone = phone;  
38.     }  
39.   
40. }  

4.hibernate.cfg.xml里面的代码如下图所示：

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1. <?xml version="1.0" encoding="UTF-8"?>  
2. <!DOCTYPE hibernate-configuration PUBLIC  
3.         "-//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="connection.driver_class">com.mysql.jdbc.Driver</property>  
8.         <property name="connection.url">jdbc:mysql://localhost:3306/hibernate?characterEncoding=utf-8</property>  
9.         <property name="dialect">org.hibernate.dialect.MySQLDialect</property>  
10.         <property name="connection.username">root</property>  
11.         <property name="connection.password">root</property>  
12.         <property name="show_sql">true</property>  
13.         <property name="format_sql">true</property>  
14.         <property name="hbm2ddl.auto">create</property>  
15.         <property name="hibernate.current_session_context_clss">thread</property>  
16.   
17.         <mapping class="entity.Students" />  
18.     </session-factory>  
19. </hibernate-configuration>  

5.TestStudents.java里面的代码如下图所示：

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1. package 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.         Configuration config = new Configuration().configure();  
15.         ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()  
16.                 .applySettings(config.getProperties()).buildServiceRegistry();  
17.         SessionFactory sessionFactory = config  
18.                 .buildSessionFactory(serviceRegistry);  
19.         SchemaExport export = new SchemaExport(config);  
20.         export.create(true, true);  
21.     }  
22.   
23. }  

6.在Navicat数据库里面新建一个数据库，数据库的名称要与上面 的数据库的名称相同。

7.运行testShemaExport类，数据库里面会自动创建一张表。