Hibernate之主键生成策略

Hibernate之主键生成策略

1.1 程序员自己控制：assigned

1.2 数据库控制: identity(标识列/自动增长) sequence

1.3 hibernate控制:increment uuid/uuid.hex

1.4 其它:native

hibernate.cfg.xml核心配置文件

Student.hbm.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 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 <hibernate-mapping>
 6     <class name="com.MavenHibernate.two.entity.Student" table="t_hibernate_student">
 7         <id name="sid" type="java.lang.Integer" column="sid">
 8               <generator class="assigned" /> 
 9             <!-- <generator class="sequence" /> -->
10               <!-- <generator class="increment" />  -->
11              <!-- <generator class="identity" />  -->
12             <!-- <generator class="sequence" /> -->
13             <!-- <generator class="sequence" > <param name="sequence_name">aaa</param> 
14                 </generator> -->
15             <!-- <generator class="com.javaxl.two.id.Myts" /> -->
16         </id>
17         <property name="sname" type="java.lang.String" column="sname">
18         </property>
19     </class>
20 </hibernate-mapping>

Student实体类与Student.hbm.xml中的name值一一对应

 1 package com.MavenHibernate.two.entity;
 2 
 3 public class Student {
 4 
 5     private Integer sid;
 6     private String sname;
 7     public Integer getSid() {
 8         return sid;
 9     }
10     public void setSid(Integer sid) {
11         this.sid = sid;
12     }
13     public String getSname() {
14         return sname;
15     }
16     public void setSname(String sname) {
17         this.sname = sname;
18     }
19     @Override
20     public String toString() {
21         return "Student [sid=" + sid + ", sname=" + sname + "]";
22     }
23     public Student(Integer sid, String sname) {
24         super();
25         this.sid = sid;
26         this.sname = sname;
27     }
28     public Student() {
29         super();
30     }
31     
32     
33 }

Worker.hbm.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 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 <hibernate-mapping>
 6     <class name="com.MavenHibernate.two.entity.Worker" table="t_hibernate_worker">
 7         <id name="wid" type="java.lang.String" column="wid">
 8             <!-- <generator class="assigned" /> -->
 9              <!-- <generator class="uuid" />  -->
10              <generator class="com.MavenHibernate.id.MyTsGenerator" /> 
11             <!-- <generator class="sequence" > <param name="sequence_name">aaa</param> 
12                 </generator> -->
13             <!-- <generator class="com.javaxl.two.id.Myts" /> -->
14         </id>
15 
16         <property name="wname" type="java.lang.String" column="wname">
17         </property>
18     </class>
19 </hibernate-mapping>

Worker.hbm.xml对应的Worker实体类

 1 package com.MavenHibernate.two.entity;
 2 
 3 public class Worker {
 4 
 5     private String wid;
 6     private String wname;
 7     public String getWid() {
 8         return wid;
 9     }
10     public void setWid(String wid) {
11         this.wid = wid;
12     }
13     public String getWname() {
14         return wname;
15     }
16     public void setWname(String wname) {
17         this.wname = wname;
18     }
19     @Override
20     public String toString() {
21         return "Worker [wid=" + wid + ", wname=" + wname + "]";
22     }
23     public Worker(String wid, String wname) {
24         super();
25         this.wid = wid;
26         this.wname = wname;
27     }
28     public Worker() {
29         super();
30     }
31     
32 }

 程序员自己控制：assigned

assigned
数据类型不限、保存前必须赋值

 1 package com.MavenHibernate.dao;
 2 
 3 import org.hibernate.Session;
 4 import org.hibernate.Transaction;
 5 
 6 import com.MavenHibernate.two.entity.Student;
 7 import com.MavenHibernate.two.entity.Worker;
 8 import com.MavenHibernate.two.util.SessionFactoryUtils;
 9 /**
10  * hibernate中的主键生成策略
11  * 1.人工控制
12  * 2.数据库控制
13  * 3.hibernate控制
14  * 4.自定义主键生成策略
15  * @author Administrator
16  *
17  */
18 public class DemoDao {       
19 
20     /**
21      * 新增学生
22      * @param stu
23      */
24     public void addStudent(Student stu) {
25         Session session = SessionFactoryUtils.openSession();
26         Transaction transaction = session.beginTransaction();
27         session.save(stu);
28         transaction.commit();
29         SessionFactoryUtils.closeSession();
30     }
31     /**
32      * 新增功能
33      * @param worker
34      */
35     public void addWorker(Worker worker) {
36         Session session = SessionFactoryUtils.openSession();
37         Transaction transaction = session.beginTransaction();
38         session.save(worker);
39         transaction.commit();
40         SessionFactoryUtils.closeSession();
41     }
42     
43     public static void testStudent() {
44         DemoDao dao = new DemoDao();
45         Student stu = new Student();
46         stu.setSname("XFQ");
47         stu.setSid(65);
48         dao.addStudent(stu);
49     }
50     
51     
52 }

 

数据库控制: identity(标识列/自动增长) sequence

Student.hbm.xml

DemoDao 
 1 package com.MavenHibernate.dao;
 2 
 3 import org.hibernate.Session;
 4 import org.hibernate.Transaction;
 5 
 6 import com.MavenHibernate.two.entity.Student;
 7 import com.MavenHibernate.two.entity.Worker;
 8 import com.MavenHibernate.two.util.SessionFactoryUtils;
 9 /**
10  * hibernate中的主键生成策略
11  * 1.人工控制
12  * 2.数据库控制
13  * 3.hibernate控制
14  * 4.自定义主键生成策略
15  * @author Administrator
16  *
17  */
18 public class DemoDao {       
19 
20     /**
21      * 新增学生
22      * @param stu
23      */
24     public void addStudent(Student stu) {
25         Session session = SessionFactoryUtils.openSession();
26         Transaction transaction = session.beginTransaction();
27         session.save(stu);
28         transaction.commit();
29         SessionFactoryUtils.closeSession();
30     }
31     /**
32      * 新增功能
33      * @param worker
34      */
35     public void addWorker(Worker worker) {
36         Session session = SessionFactoryUtils.openSession();
37         Transaction transaction = session.beginTransaction();
38         session.save(worker);
39         transaction.commit();
40         SessionFactoryUtils.closeSession();
41     }
42     
43     public static void testStudent() {
44         DemoDao dao = new DemoDao();
45         Student stu = new Student();
46         stu.setSname("XFQ");
47         stu.setSid(70);
48         dao.addStudent(stu);
49     }
50     
51 
58 }

hibernate控制:increment uuid/uuid.hex

是由容器自动生成的一个32位的字符串，.hex代表的是十六进制
32位的字符串，无需赋值，

Worker.hbm.xml

 1 package com.MavenHibernate.dao;
 2 
 3 import org.hibernate.Session;
 4 import org.hibernate.Transaction;
 5 
 6 import com.MavenHibernate.two.entity.Student;
 7 import com.MavenHibernate.two.entity.Worker;
 8 import com.MavenHibernate.two.util.SessionFactoryUtils;
 9 /**
10  * hibernate中的主键生成策略
11  * 1.人工控制
12  * 2.数据库控制
13  * 3.hibernate控制
14  * 4.自定义主键生成策略
15  * @author Administrator
16  *
17  */
18 public class DemoDao {       
19 
20     /**
21      * 新增学生
22      * @param stu
23      */
24     public void addStudent(Student stu) {
25         Session session = SessionFactoryUtils.openSession();
26         Transaction transaction = session.beginTransaction();
27         session.save(stu);
28         transaction.commit();
29         SessionFactoryUtils.closeSession();
30     }
31     /**
32      * 新增功能
33      * @param worker
34      */
35     public void addWorker(Worker worker) {
36         Session session = SessionFactoryUtils.openSession();
37         Transaction transaction = session.beginTransaction();
38         session.save(worker);
39         transaction.commit();
40         SessionFactoryUtils.closeSession();
41     }
42     
43     public static void testStudent() {
44         DemoDao dao = new DemoDao();
45         Student stu = new Student();
46         stu.setSname("XFQ");
47         stu.setSid(70);
48         dao.addStudent(stu);
49     }
50     
51     public static void main(String[] args) {
52         DemoDao dao = new DemoDao();
53         Worker worker = new Worker();
54         worker.setWname("肖龙飞");
55         dao.addWorker(worker);
56     }
57     
58 }

创建主键生成器类
实现org.hibernate.id.IdentifierGenerator接口即可,并还可以实现org.hibernate.id.Configurable接口来读取一些配置信息

MyTsGenerator 
 1 package com.MavenHibernate.id;
 2 
 3 import java.io.Serializable;
 4 import java.text.SimpleDateFormat;
 5 import java.util.Date;
 6 
 7 import org.hibernate.HibernateException;
 8 import org.hibernate.engine.spi.SharedSessionContractImplementor;
 9 import org.hibernate.id.IdentifierGenerator;
10 
11 public class MyTsGenerator implements IdentifierGenerator {
12 
13     @Override
14     public Serializable generate(SharedSessionContractImplementor session, Object object) throws HibernateException {
15         // TODO Auto-generated method stub
16         SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-DD HH:mm:ss");
17         return "book_order_"+sdf.format(new Date());
18     }
19 
20 }

Worker.hbm.xml

 

posted @ 2019-08-03 21:12  Mr.XiaoQi  阅读(317)  评论(0)  编辑  收藏  举报