Hibernate,JPA注解@DynamicInsert和@DynamicUpdate,Hibernate如何插入sysdate

作者: xiluhua
发布时间:2015-07-08 18:39:10

@DynamicInsert属性:设置为true,设置为true,表示insert对象的时候,生成动态的insert语句,如果这个字段的值是null就不会加入到insert语句当中.默认false。

比如希望数据库插入日期或时间戳字段时,在对象字段为空的情况下,表字段能自动填写当前的sysdate。

@DynamicUpdate属性:设置为true,设置为true,表示update对象的时候,生成动态的update语句,如果这个字段的值是null就不会被加入到update语句中,默认false。

比如只想更新某个属性,但是却把整个对象的属性都更新了,这并不是我们希望的结果,我们希望的结果是:我更改了哪些字段,只要更新我修改的字段就够了。

 

@DynamicInsert

用例代码如下:

  • 数据库DDL语句:
1 create table CAT  2 (  3   id          VARCHAR2(32 CHAR) not null,  4   create_time TIMESTAMP(6) default sysdate,  5   update_time TIMESTAMP(6),  6   cat_name    VARCHAR2(255 CHAR)  7 )
  • hibernate.cfg.xml
 1 <?xml version="1.0" encoding="utf-8" ?>   2 <!DOCTYPE hibernate-configuration   3  PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"   4  "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">   5 <hibernate-configuration>   6     <session-factory>   7         <!-- 数据库驱动配置 -->   8         <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>   9         <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>  10         <property name="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl</property>  11         <property name="connection.username">wxuatuser</property>  12         <property name="connection.password">xlh</property>  13         <property name="show_sql">true</property>  14         <!-- 自动执行DDL属性是update,不是true -->  15         <property name="hbm2ddl.auto">update</property>  16         <!-- hibernate实体类 -->  17           18         <mapping class="a2_DynamicInsert_Update.Cat"/>  19           20     </session-factory>  21 </hibernate-configuration>
  • java类

实体类 - 基类 

 1 package model;   2    3 import java.io.Serializable;   4 import java.util.Date;   5 import javax.persistence.Column;   6 import javax.persistence.GeneratedValue;   7 import javax.persistence.Id;   8 import javax.persistence.MappedSuperclass;   9 import org.hibernate.annotations.GenericGenerator;  10   11 /**  12  * 实体类 - 基类  13  */  14 @MappedSuperclass  15 public class BaseEntity implements Serializable {  16   17     private static final long serialVersionUID = -6718838800112233445L;  18   19     private String id;// ID  20     private Date create_time;// 创建日期  21     private Date update_time;// 修改日期  22     @Id  23     @Column(length = 32, nullable = true)  24     @GeneratedValue(generator = "uuid")  25     @GenericGenerator(name = "uuid", strategy = "uuid")  26     public String getId() {  27         return id;  28     }  29   30     public void setId(String id) {  31         this.id = id;  32     }  33   34     @Column(updatable = false)  35     public Date getCreate_time() {  36         return create_time;  37     }  40     public void setCreate_time(Date create_time) {  41         this.create_time = create_time;  42     }  43   44     public Date getUpdate_time() {  45         return update_time;  46     }  47   48     public void setUpdate_time(Date update_time) {  49         this.update_time = update_time;  50     }  51   52     @Override  53     public int hashCode() {  54         return id == null ? System.identityHashCode(this) : id.hashCode();  55     }  56   58     @Override  59     public boolean equals(Object obj) {  60         if (this == obj) {  61             return true;  62         }  63         if (obj == null) {  64             return false;  65         }  66         if (getClass().getPackage() != obj.getClass().getPackage()) {  67             return false;  68         }  69         final BaseEntity other = (BaseEntity) obj;  70         if (id == null) {  71             if (other.getId() != null) {  72                 return false;  73             }  74         } else if (!id.equals(other.getId())) {  75             return false;  76         }  77         return true;  78     }  79 }

实体类

 1 package a2_DynamicInsert_Update;   2 import javax.persistence.Entity;   3 import model.BaseEntity;   4 import org.hibernate.annotations.DynamicInsert;   5 import org.hibernate.annotations.DynamicUpdate;   6    7 @Entity   8 @DynamicInsert   9 @DynamicUpdate  10 public class Cat extends BaseEntity{  11     /**  12      * 实体类  13      */  14     private static final long serialVersionUID = -2776330321385582872L;  15       16     private String cat_name;  17   18     public String getCat_name() {  19         return cat_name;  20     }  21   22     public void setCat_name(String cat_name) {  23         this.cat_name = cat_name;  24     }  25 }
Dao
 1 package daoUtil;   2    3 import org.hibernate.HibernateException;   4 import org.hibernate.Session;   5 import org.hibernate.SessionFactory;   6 import org.hibernate.Transaction;   7 import org.hibernate.cfg.Configuration;   8 import org.hibernate.service.ServiceRegistry;   9 import org.hibernate.service.ServiceRegistryBuilder;  10   11 public class HibernateUtil {  12   13     private static final SessionFactory sessionFactory;  14   15     static {  16         try {  17             Configuration cfg = new Configuration().configure();  18             ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()  19                     .applySettings(cfg.getProperties()).buildServiceRegistry();  20             sessionFactory = cfg.buildSessionFactory(serviceRegistry);  21         } catch (Throwable ex) {  22             // Log exception!  23             throw new ExceptionInInitializerError(ex);  24         }  25     }  26   27     public static Session getSession() throws HibernateException {  28         return sessionFactory.openSession();  29     }  30   31     public static Object save(Object obj){  32         Session session = HibernateUtil.getSession();  33         Transaction tx = null;  34         try {  35             tx = session.beginTransaction();  36             session.save(obj);  37             tx.commit();  38         } catch (RuntimeException e) {  39             if (tx != null) {  40                 tx.rollback();  41             }  42             throw e;  43         } finally {  44             session.close();  45         }  46         return obj;  47     }  48       49     public static void delete(Class<?> clazz,String id){  50         Session session = HibernateUtil.getSession();  51         Transaction tx = null;  52         try {  53             tx = session.beginTransaction();  54             Object obj = session.get(clazz,id);  55             session.delete(obj);  56             tx.commit();  57         } catch (RuntimeException e) {  58             if (tx != null) {  59                 tx.rollback();  60             }  61             throw e;  62         } finally {  63             session.close();  64         }  65     }  66 }
main
 1 package a2_DynamicInsert_Update;   2 import a2_DynamicInsert_Update.Cat;   3 import daoUtil.HibernateUtil;   4    5 public class Test_DynamicInsert {   6    7     public static void main(String[] args) {   8         Cat cat = new Cat();   9         cat.setCat_name("test2@DynamicInsert");  10         HibernateUtil.save(cat);  11     }  12 }
@DynamicInsert注解下Hibernate日志打印SQL:
Hibernate: insert into Cat (cat_name, id) values (?, ?)  

反之

Hibernate: insert into Cat (create_time, update_time, cat_name, id) values (?, ?, ?, ?)  

 

@DynamicUpdate

写了个main程序测试:代码如下:

  • 数据库DML语句:
insert into CAT (ID, CAT_NAME, CREATE_TIME, UPDATE_TIME)  values ('8a6cc5a34c456829014c45682a860000', 'test@555', SYSDATE, SYSDATE);
  • hibernate.cfg.xml 同上
  • java类
实体类,Dao 同上。

main
 1 package a2_DynamicInsert_Update;   2 import org.hibernate.Session;   3 import org.hibernate.Transaction;   4 import daoUtil.HibernateUtil;   5    6 public class Test_DynamicUpdate {   7    8     public static void main(String[] args) {   9         Session session = HibernateUtil.getSession();  10         Transaction tx = null;  11         try {  12             tx = session.beginTransaction();  13             Cat cat = (Cat)session.get(Cat.class, "8a6cc5a34c6e7f32014c6e7f33500000");  14             cat.setCat_name("test@DynamicUpdate");  15             tx.commit();  16         } catch (RuntimeException e) {  17             if (tx != null) {  18                 tx.rollback();  19             }  20             throw e;  21         } finally {  22             session.close();  23         }  24           25     }  26 }
  

Cat实体类@DynamicUpdate注解下Hibernate日志打印SQL:

说明:如果字段有更新,Hibernate才会对该字段进行更新

Hibernate: update Cat set update_time=? where id=?

反之Cat实体类去掉@DynamicUpdate

说明:不管字段有没有更新,Hibernate都会对该字段进行更新

Hibernate: update Cat set update_time=?, cat_name=? where id=?  

 

Hibernate在执行更新操作前,会比对一下当前Session上下文中的对象需要更新的对象数据是否一致,也就是说会确认数据有没有变化,没变化的话,无论写多少次session.update(cat),都不会执行更新操作。

 

源码地址:http://files.cnblogs.com/files/xiluhua/hibernate%40DynamicInsert_Update.rar

环境:JDK1.6,MAVEN

 

标签: Hibernate
来源:http://www.cnblogs.com/xiluhua/p/4359823.html

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