@DynamicInsert和@DynamicUpdate，Hibernate如何插入sysdate
浏览数：63 /
时间：2015年06月09日
@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
写了个main程序测试：代码如下：
- 数据库DDL语句：
1 create table CAT
2 (
3 id VARCHAR2(32) not null,
4 CAT_NAME VARCHAR2(32) default sysdate,
5 create_time DATE,
6 update_time DATE
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 6 <hibernate-configuration> 7 <session-factory> 8 <!-- 数据库驱动配置 --> 9 <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property> 10 <property name="connection.driver_class">oracle.jdbc.OracleDriver</property> 11 <property name="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl</property> 12 <property name="connection.username">wxuatuser</property> 13 <property name="connection.password">xlh</property> 14 <property name="show_sql">true</property> 15 16 <!-- hibernate实体类 --> 17 <mapping class="test2.Cat"/> 18 </session-factory> 19 </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 } 38 39 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 57 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 test2; 2 import javax.persistence.Entity; 3 import model.BaseEntity; 4 import org.hibernate.annotations.DynamicInsert; 5 6 @Entity 7 @DynamicInsert 8 public class Cat extends BaseEntity{ 9 /** 10 * 实体类 11 */ 12 private static final long serialVersionUID = -2776330321385582872L; 13 14 private String cat_name; 15 16 public String getCat_name() { 17 return cat_name; 18 } 19 20 public void setCat_name(String cat_name) { 21 this.cat_name = cat_name; 22 } 23 }
main入口
1 package test2; 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 import test2.Cat; 11 12 public class HibernateUtil { 13 14 private static final SessionFactory sessionFactory; 15 16 static { 17 try { 18 Configuration cfg = new Configuration().configure(); 19 ServiceRegistry serviceRegistry = new ServiceRegistryBuilder() 20 .applySettings(cfg.getProperties()).buildServiceRegistry(); 21 sessionFactory = cfg.buildSessionFactory(serviceRegistry); 22 } catch (Throwable ex) { 23 // Log exception! 24 throw new ExceptionInInitializerError(ex); 25 } 26 } 27 28 public static Session getSession() throws HibernateException { 29 return sessionFactory.openSession(); 30 } 31 32 public static void main(String[] args) { 33 Session session = HibernateUtil.getSession(); 34 Transaction tx = null; 35 try { 36 tx = session.beginTransaction(); 37 Cat cat = new Cat(); 38 cat.setCat_name("cat@DynamicInsert"); 39 session.save(cat); 40 tx.commit(); 41 } catch (RuntimeException e) { 42 if (tx != null) { 43 tx.rollback(); 44 } 45 throw e; 46 } finally { 47 session.close(); 48 } 49 } 50 }
@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：Cat 同上。
main入口
1 package test2; 2 3 import java.util.Date; 4 5 import org.hibernate.HibernateException; 6 import org.hibernate.Session; 7 import org.hibernate.SessionFactory; 8 import org.hibernate.Transaction; 9 import org.hibernate.cfg.Configuration; 10 import org.hibernate.service.ServiceRegistry; 11 import org.hibernate.service.ServiceRegistryBuilder; 12 13 public class HibernateUtil_DynamicUpdate { 14 15 private static final SessionFactory sessionFactory; 16 17 static { 18 try { 19 Configuration cfg = new Configuration().configure(); 20 ServiceRegistry serviceRegistry = new ServiceRegistryBuilder() 21 .applySettings(cfg.getProperties()).buildServiceRegistry(); 22 sessionFactory = cfg.buildSessionFactory(serviceRegistry); 23 } catch (Throwable ex) { 24 // Log exception! 25 throw new ExceptionInInitializerError(ex); 26 } 27 } 28 29 public static Session getSession() throws HibernateException { 30 return sessionFactory.openSession(); 31 } 32 33 public static void main(String[] args) { 34 Session session = HibernateUtil_DynamicUpdate.getSession(); 35 Transaction tx = null; 36 try { 37 tx = session.beginTransaction(); 38 Cat cat = (Cat)session.get(Cat.class, "8a6cc5a34c456829014c45682a860000"); 39 cat.setUpdate_time(new Date()); 40 cat.setCat_name("test@555"); 41 session.update(cat); 42 tx.commit(); 43 } catch (RuntimeException e) { 44 if (tx != null) { 45 tx.rollback(); 46 } 47 throw e; 48 } finally { 49 session.close(); 50 } 51 } 52 }
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上下文中的对象与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%40DynamicUpdate.rar
环境：JDK1.6，MAVEN
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