知识大全 Hibernate Annotations 实战介绍

Posted 2022-07-18 数据库

篇首语：无私是稀有的道德，因为从它身上是无利可图的。本文由小常识网(cha138.com)小编为大家整理，主要介绍了知识大全 Hibernate Annotations 实战介绍相关的知识，希望对你有一定的参考价值。

Hibernate Annotations 实战介绍 以下文字资料是由(全榜网网www.cha138.com)小编为大家搜集整理后发布的内容，让我们赶快一起来看一下吧！

从 hbm xml 到 Annotations　　下面让我们先看一个通常用 hbm xml 映射文件的例子有个类 HibernateUtil java 也就是 Hibernate文档中推荐的工具类 Person java Test java 测试用的类都在test hibernate 包中每个类的代码如下:

　　HibernateUtil:

　　 package test hibernate; import hibernate HibernateException; import hibernate Session; import hibernate SessionFactory; import hibernate cfg Configuration; public class HibernateUtil public static final SessionFactory sessionFactory; static try sessionFactory = new Configuration() nfigure() buildSessionFactory(); catch (HibernateException e) // TODO Auto generated catch block e printStackTrace(); throw new ExceptionInInitializerError(e); public static final ThreadLocal<Session> session = new ThreadLocal<Session>(); public static Session currentSession() throws HibernateException Session s = session get(); if(s == null) s = sessionFactory openSession(); session set(s); return s; public static void closeSession() throws HibernateException Session s = session get(); if(s != null) s close(); session set(null);

　　Person:

　　 package test hibernate; import java util LinkedList; import java util List; /** * */ @SuppressWarnings( serial ) public class Person implements java io Serializable // Fields private Integer id; private String name; private String sex; private Integer age; private List list = new LinkedList(); // Collection accessors public List getList() return list; public void setList(List list) this list = list; /** default constructor */ public Person() /** constructor with id */ public Person(Integer id) this id = id; // Property accessors public Integer getId() return this id; public void setId(Integer id) this id = id; public String getName() return this name; public void setName(String name) this name = name; public String getSex() return this sex; public void setSex(String sex) this sex = sex; public Integer getAge() return this age; public void setAge(Integer age) this age = age;

　　Test:

　　 /* * Created on * @author */ package test hibernate; import java sql SQLException; import hibernate FlushMode; import hibernate HibernateException; import hibernate Session; import hibernate Transaction; public class Test public static void main(String [] args) Session s = HibernateUtil currentSession(); Transaction tx = s beginTransaction(); // Person p = (Person) s load(Person class ); // System out println(p getName()); Person p = new Person(); p setAge( ); p setName( icerain ); p setSex( male ); s save(p); s flush(); /* Person p = (Person) s get(Person class new Integer( )); System out println(p getName()); p setName( ice ); s saveOrUpdate(p ); s flush(); Person p = (Person) s get(Person class new Integer( )); System out println(p getName()); s delete(p ); */ mit(); try System out println(p getName()); catch (Exception e) // TODO Auto generated catch block e printStackTrace(); HibernateUtil closeSession();

　　hibernate cfg xml 配置文件如下利用mysql 数据库

　　<?xml version= encoding= UTF ?>

　　<property name= nnection driver_class > gjt mm mysql Driver</property>

　　<property name= nnection password >你的数据库密码</property>

　　<property name= nnection url >jdbc:mysql://localhost/数据库名</property>

　　<property name= hibernate dialect > hibernate dialect MySQLDialect</property>

　　<property name= hibernate transaction factory_class > hibernate transaction JDBCTransactionFactory</property>

　　<property name= hibernate transaction auto_close_session >false</property>

　　<property name= hibernate hbm ddl auto >update</property>

　　</session factory>

　　</hibernate configuration>

　　其中配置了<property name= hibernate hbm ddl auto >update</property>属性自动导入数据库ddl 生产的ddl sql语句如下

　　create table person (id integer not null auto_increment name varchar( ) sex varchar( ) age integer person integer primary key (id))

　　alter table person add index FKC E B C A C (person) add constraint FKC E B C A C foreign key (person) references person (id)

　　而Person hbm xml 文件如下:

　　<?xml version= ?>

　　</id>

　　</property>

　　</property>

　　</property>

　　</bag>

　　</class>

　　</hibernate mapping>

　　下面让我们看看利用 Hibernate Annotations 如何做只要三个类不再需要 hbm xml配置文件:

　　还要把用到的两个jar文件放入的类路径中具体如何做请参考 Hibernate Annotations 中文文档

　　HibernateUtil java 也就是 Hibernate文档中推荐的工具类 Person java 一个持久化的类 Test java 测试用的类都在test hibernate annotation 包中每个类的代码如下:

　　HibernateUtil

　　 package test hibernate annotation; import hibernate HibernateException; import hibernate Session; import hibernate SessionFactory; import hibernate cfg AnnotationConfiguration; import hibernate cfg Configuration; public class HibernateUtil public static final SessionFactory sessionFactory; static try sessionFactory = new AnnotationConfiguration() //注意: 建立 SessionFactory于前面的不同 addPackage( test hibernate annotation ) addAnnotatedClass(Person class) nfigure() buildSessionFactory(); //new Configuration(nfigure() buildSessionFactory(); catch (HibernateException e) // TODO Auto generated catch block e printStackTrace(); throw new ExceptionInInitializerError(e); public static final ThreadLocal<Session> session = new ThreadLocal<Session>(); public static Session currentSession() throws HibernateException Session s = session get(); if(s == null) s = sessionFactory openSession(); session set(s); return s; public static void closeSession() throws HibernateException Session s = session get(); if(s != null) s close(); session set(null);

　　Person:

　　 package test hibernate annotation; import java util LinkedList; import java util List; import javax persistence AccessType; import javax persistence Basic; import javax persistence Entity; import javax persistence GeneratorType; import javax persistence Id; import javax persistence OneToMany; import javax persistence Table; import javax persistence Transient; /** * */ @SuppressWarnings( serial ) @Entity(access = AccessType PROPERTY) //定义该类为实体类 @Table //映射表 public class Person implements java io Serializable // Fields private Integer id; private String name; private String sex; private Integer age; private List list = new LinkedList(); // Constructors /** default constructor */ public Person() /** constructor with id */ public Person(Integer id) this id = id; // Property accessors @Id public Integer getId() return this id; public void setId(Integer id) this id = id; @Basic public String getName() return this name; public void setName(String name) this name = name; @Basic public String getSex() return this sex; public void setSex(String sex) this sex = sex; @Basic public Integer getAge() return this age; public void setAge(Integer age) this age = age; @Transient //由于本例不打算演示集合映射所有声明该属性为 Transient public List getList() return list; public void setList(List list) this list = list;

　　注意该实体类中的属性都使用了默认值

　　Test java 代码同上

　　不需要了 hbm xml 映射文件是不是简单了一些给人认为简化了一些不是主要目的主要是可以了解一下 EJB 的持久化机制提高一下开发效率才是重要的

　　好了本例就完了感觉怎么样了欢迎你来批批

　　PS:

　　生成的数据库表和程序执行后的数据库情况如下

　　mysql> describe person;+ + + + + + +| Field | Type | Null | Key | Default | Extra |+ + + + + + +| id | int( ) | NO | PRI | NULL | auto_increment || name | varchar( ) | YES | | NULL | || sex | varchar( ) | YES | | NULL | || age | int( ) | YES | | NULL | || person | int( ) | YES | MUL | NULL | |+ + + + + + + rows in set ( sec)

cha138/Article/program/Java/ky/201311/28051