Hibernate注解Annotation-白红宇

Hibernate注解Annotation

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发布时间：2019-06-14

本文共 3742 字，大约阅读时间需要 12 分钟。

大部分仍然使用javax.persistence中的注解，有些Hibernate扩展的注解，在org.hibernate.annotations包中，如GenericGenerator.

使用hibernate.cfg.xml中配置的事务，使用<mapping class="完整类名"/>加载注解的持久化类。Hibernate中可以混合使用注解和xml映射文件。

注解后不能使用Configuration类，而是AnnotationConfiguration类初始化Hibernate

1         SessionFactory sFactory=new AnnotationConfiguration() 2                               .configure().buildSessionFactory(); 3         Session session=sFactory.getCurrentSession(); 4         Transaction tx=session.beginTransaction(); 5         User user=new User(); 6         user.setUsername("tazi2"); 7         user.setPassword("12345"); 8         session.save(user); 9         tx.commit();

注解种类：

@Entity @Table @Id @Column @Transient(非持久化属性) @Temporal(时间精度) @ManyToOne @...

在类前

@NamedQueries({@NamedQuery(name="getById",query="from User where id=:id")})

使用方法与在xml配置的命名查询相同

1         Query query=session.getNamedQuery("getById"); 2         query.setInteger("id", 4); 3         User user=(User)query.uniqueResult(); 4         System.out.println(user.getUsername());

@Version乐观锁 @Cache二级缓存 @Filters @FilterDef

@GeneratedValue默认为AUTO,根据底层数据库决定。还可以用Hibernate扩展的@GenericGenerator

例子：

package com.tazi.domin; import java.sql.Timestamp; import java.util.Date; import java.util.HashSet; import java.util.Set; import javax.persistence.CascadeType; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.Lob; import javax.persistence.ManyToOne; /**  * Product entity. @author MyEclipse Persistence Tools */ @Entity public class Product implements java.io.Serializable {
   // Fields     @Id     @GeneratedValue(strategy=GenerationType.IDENTITY) private Integer id;     @Column(length=20,nullable=false) private String name;     @Column(scale=2) private Float price;     @Lob private String description;     @ManyToOne     @JoinColumn(name="CATEGORY_ID")//,referencedColumnName="ID"     private Category category;  // Constructors     public Category getCategory() {
   return category;     } public void setCategory(Category category) {
   this.category = category;     } //... Property accessors    }

Category.java

1 package com.tazi.domin;  2  3 import java.util.HashSet;  4 import java.util.Set;  5  6 import javax.persistence.CascadeType;  7 import javax.persistence.Column;  8 import javax.persistence.Entity;  9 import javax.persistence.FetchType; 10 import javax.persistence.GeneratedValue; 11 import javax.persistence.GenerationType; 12 import javax.persistence.Id; 13 import javax.persistence.OneToMany; 14 15 /** 16  * Category entity. @author MyEclipse Persistence Tools 17  */ 18 @Entity 19 public class Category implements java.io.Serializable {
   20 21     // Fields 22     @Id 23     @GeneratedValue(strategy=GenerationType.IDENTITY) 24     private Integer id; 25     @Column 26     private String name; 27     private String description; 28     @OneToMany( 29         cascade={CascadeType.ALL}, 30         fetch=FetchType.EAGER, //使用List不能使用eager,使用Set可以 31         mappedBy="category" 32     ) 33     private Set
     
       products = new HashSet(0); 34 35     // Constructors 36 37     /** default constructor */ 38     public Category() {
   39     } 40     /** minimal constructor */ 41     public Category(String name) {
   42         this.name = name; 43     } 44     /** full constructor */ 45     public Category(String name, String description, Set products) {
   46         this.name = name; 47         this.description = description; 48         this.products = products; 49     } 50     //... Property accessors 51 }