hibernate的相关学习

1.hibernate是个orm框架。也就是对象关系型映射。拥有三种状态（瞬时态，持久态，游离态）

瞬时态就是刚创建的对象，和数据库没有对应的数据映射

持久态就是在session的管理范围之内

游离态就是与数据库有映射，但是不在session的管理之中

搭建hibernate

1.引入jar包如下图

hibernate的相关学习

2.创建hibernate.cfg.xml文件。设置相关配置如下

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
   <session-factory>
       <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> 数据库驱动
       <property name="hibernate.connection.password">root</property> 数据库密码
       <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property> 数据库链接
       <property name="hibernate.connection.username">root</property> ----数据库账号
       <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> ---设置数据库方言
       <property name="hibernate.current_session_context_class">thread</property> ----设置多线程

//注解方式配置
       <mapping class="com.seve.entity.Areainfo" /> ----配置对应的实体数据

//xml文件方式配置
<mapping rescorce="com/seve/entity/Areainfo.xml"> -----配置对应的实体xml文件

   </session-factory>
</hibernate-configuration>

3.设置对应的实体（可以使用hibernate.reveng.xml进行生成，也可手写）

package com.seve.entity;
// Generated by Hibernate Tools 4.3.5.Final

import java.util.HashSet;
import java.util.Set;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import static javax.persistence.GenerationType.IDENTITY;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

/**
* Areainfo generated by hbm2java
*/
@Entity
@Table(name = "areainfo", catalog = "test")
public class Areainfo implements java.io.Serializable
{

private Integer aid;
private String aname;
private String aremark;
private Set<Companyinfo> companyinfos = new HashSet<Companyinfo>(0);

public Areainfo()
{
}

public Areainfo(String aname, String aremark, Set<Companyinfo> companyinfos)
{
this.aname = aname;
this.aremark = aremark;
this.companyinfos = companyinfos;
}

@Id
@GeneratedValue(strategy = IDENTITY)

@Column(name = "aid", unique = true, nullable = false)
public Integer getAid()
{
return this.aid;
}

public void setAid(Integer aid)
{
this.aid = aid;
}

@Column(name = "aname", length = 50)
public String getAname()
{
return this.aname;
}

public void setAname(String aname)
{
this.aname = aname;
}

@Column(name = "aremark", length = 100)
public String getAremark()
{
return this.aremark;
}

public void setAremark(String aremark)
{
this.aremark = aremark;
}

@OneToMany(fetch = FetchType.LAZY, mappedBy = "areainfo")
public Set<Companyinfo> getCompanyinfos()
{
return this.companyinfos;
}

public void setCompanyinfos(Set<Companyinfo> companyinfos)
{
this.companyinfos = companyinfos;
}

}