hibernate对象管理

1、多对一关联

xml配置

1）、一个组可以有多个用户，一个用户所以一个主。User表与Group表的关系是多对已

User表

package com.mr.cheng.associations;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
@Table(name="t_user")
public class User {private int id;private String name;private Group group;public Group getGroup() {return group;}public void setGroup(Group group) {this.group = group;}@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

　　Group表

package com.mr.cheng.associations;import java.util.HashSet;
import java.util.Set;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.OrderBy;
import javax.persistence.Table;@Entity
@Table(name="t_group")
public class Group {private int id;private String name;@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

　　User.hbm.<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.bjsxt.hibernate.User" table="t_user"><id name="id"><generator class="native"></generator></id><property name="name"></property><many-to-one name="group" column="groupId"></many-to-one></class></hibernate-mapping>

　　Group.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.mr.cheng.associations.Group" table="tt_group"><id name="id"><generator class="native"></generator></id><property name="name"></property></class></hibernate-mapping>

　　2）、一对多配置

　　在Group对象中加一个Set类型的字段，代码如下

package com.mr.cheng.associations;import java.util.HashSet;
import java.util.Set;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.OrderBy;
import javax.persistence.Table;@Entity
@Table(name="t_group")
public class Group {private int id;private String name;private Set<User> userSet = new HashSet<User>();public Set<User> getUserSet() {return userSet;}public void setUserSet(Set<User> userSet) {this.userSet = userSet;}@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

Group.hbm.xml配置如下：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.mr.cheng.associations.Group" table="tt_group"><id name="id"><generator class="native"></generator></id><property name="name"></property><set name="userSet"><key column="groupId"></key><one-to-many class="com.mr.cheng.associations.User"/></set></class></hibernate-mapping>

　　配置一对多时，在Group.hbm.xml文件中set属性名字对应Group的字段，key中的Column属性对应外键名字，即是通过groupId进行关联。 one-to-many 中的class对应关联的类。

　　User表

package com.mr.cheng.associations;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
@Table(name="t_user")
public class User {private int id;private String name;@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

　　User.hbm.xml配置如下：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.mr.cheng.associations.User" table="tt_user"><id name="id"><generator class="native"></generator></id><property name="name"></property></class></hibernate-mapping>

3）、多对一与已对多双向关联

User 对象代码如下：

package com.mr.cheng.associations;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
@Table(name="t_user")
public class User {private int id;private String name;private Group group;public Group getGroup() {return group;}public void setGroup(Group group) {this.group = group;}@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

　Group对象代码如下：　

package com.mr.cheng.associations;import java.util.HashSet;
import java.util.Set;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.OrderBy;
import javax.persistence.Table;@Entity
@Table(name="t_group")
public class Group {private int id;private String name;private Set<User> userSet = new HashSet<User>();public Set<User> getUserSet() {return userSet;}public void setUserSet(Set<User> userSet) {this.userSet = userSet;}@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

　　User.hbm.xml配日志如下：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.mr.cheng.associations.User" table="tt_user"><id name="id"><generator class="native"></generator></id><property name="name"></property><many-to-one name="group" column="groupId"></many-to-one></class></hibernate-mapping>

　　Group.hbm.xml配置如下：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.mr.cheng.associations.Group" table="tt_group"><id name="id"><generator class="native"></generator></id><property name="name"></property><set name="userSet"><key column="groupId"></key><one-to-many class="com.mr.cheng.associations.User"/></set></class></hibernate-mapping>

　　注意：group.hbm.xml中的一对多配置时 key 中column属性的值必须与User.hbm.xml中的 many-to-one属性中的name值一直。否则出现意想不到的结果。

4）、多对多双向关联

一个用户可以选择多个房间，一个房间可以住多个人，因此User表与Room表的关系就为多对多的关系。

User对象代码如下：

package com.mr.cheng.associations;import java.util.HashSet;
import java.util.Set;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
@Table(name="t_user")
public class User {private int id;private String name;private Set<Room> roomSet = new HashSet<Room>();public Set<Room> getRoomSet() {return roomSet;}public void setRoomSet(Set<Room> roomSet) {this.roomSet = roomSet;}@Id@GeneratedValuepublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

　　Room对象的代码如下：

package com.mr.cheng.associations;import java.util.HashSet;
import java.util.Set;public class Room {private int id;private String name;private Set<User> userSet = new HashSet<User>();public Set<User> getUserSet() {return userSet;}public void setUserSet(Set<User> userSet) {this.userSet = userSet;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

　　User.hbm.xml的配置如下：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.mr.cheng.associations.User" table="tt_user"><id name="id" column="userId"><generator class="native"></generator></id><property name="name"></property><set name="roomSet" inverse="true" table="tt_user_room"><key column="userId"></key><many-to-many class="com.mr.cheng.associations.Room" column="roomId"></many-to-many></set></class></hibernate-mapping>

　　Room.hbm.xml的配置如下：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.mr.cheng.associations.Room" table="tt_room"><id name="id" column="roomId"><generator class="native"></generator></id><property name="name"></property><set name="userSet" table="tt_user_room"><key column="roomId"></key><many-to-many class="com.mr.cheng.associations.User" column="userId"></many-to-many></set></class></hibernate-mapping>

转载于:https://www.cnblogs.com/chengAddress/p/4326089.html

hibernate对象管理相关推荐

SSH学习-Hibernate对象生命周期管理
Hibernate对象就是java中的实体对象,管理就是在实体对象的生命周期内被Hibernate的操作,Hibernate对象的生命周期其实就是实体对象的生命周期(从创建到最后被GC回收),期间对实 ...
Hibernate学习（4）- Hibernate对象的生命周期
1.Hibernate对象的生命周期(瞬时状态.持久化状态.游离状态) 1.瞬时状态(Transient): 使用new操作符初始化的对象就是瞬时状态,没有跟任何数据库数据相关联: 2.持久化状态(P ...
菜鸟学SSH（八）——Hibernate对象的三种状态
前面写了几篇关于SSH的博客,但不是Struts就是Spring,Hibernate还从来没写过呢.说好是SSH的,怎么可以光写那两个,而不写Hibernate呢对吧.今天就先说说Hibernate对 ...
Hibernate 对象的三种状态
Hibernate 对象的三种状态瞬时(transient): 由new操作符创建,且尚未与Hibernate Session关联的对象被认定为瞬时(Transient)的.瞬时(Transient ...
Hibernate对象状态
Hibernate对象状态在hibernate中有三种状态:瞬时态(Transient). 持久态(Persistent).脱管态(Detached).处于持久态的对象也称为PO(Persisten ...
Hibernate - 对象关系映射文件(*.hbm.xml)详解
对象关系映射文件,即POJO 类和数据库的映射文件*.hbm.xml(映射文件的扩展名为 .hbm.xml). POJO 类和关系数据库之间的映射可以用一个XML文档来定义. 通过 POJO 类的数据 ...
Hibernate对象的状态和映射
一. Hibernate对象的状态实体对象的三种状态: 1) 暂态(瞬时态)(Transient)---实体在内存中的自由存在,它与数据库的记录无关. po在DB中无记录(无副本),po和sessi ...
Windows内核对象管理
Windows内核情景分析:所有的分析都有ReactOS的源代码(以及部分由微软公开的源代码)作为依据:不清楚版本: 对象管理 Windows把一些核心功能作为内核对象来管理,这些 ...
【Hibernate框架开发之五】Hibernate对象的三种状态Session常用方法
1. Hibernate对象的三种状态:(图解如下:) 如图所示,Hibernate对象有三种状态,1.Transient 2.Persistent 3.Detached; 三种状态的区别如下: 1 ...

hibernate对象管理

hibernate对象管理相关推荐

最新文章

热门文章