Hibernate's about many-to-one one-way association mappings

A multi-pair one-way Association mapping for "Hibernate"

In the development of the project many-to-one one-way association mapping is the most common, association mapping! This is an emphasis on detailed explanation!

For example, we now have a group and people (person)

(Persontable )

Id	Name
1	Tom
2	John doe

(Group table )

Id	Name	p_id
1	Finance Group	1
2	Finance Group	2

From the above table we find that there is no duplication of data? The Finance group is repeating!

So, in many-to-one one-way mappings, we usually associate fewer parties with a foreign key on many sides.

So in this relationship (group) is a small party, (person) is a multi-party, a group can have more than one!

(Group table )

Id	Name
1	Finance Group
2	Development Group

(Persontable )

Id	Name	g_id
1	Tom	1
2	John doe	1

The above relationship is the normal business logic!

ok, let's look at our annotations Configuration!

@Entity @table (name= "T_user") publicclass person {    private integer id ;      private string name;    private  integer age;    private group group;          @ManyToOne     public group getgroup ()  {        returngroup;    }    publicvoid setgroup ( Groupgroup)  {       this.group = group;     }     @Id      @GeneratedValue     public  Integer getid ()  {       returnid;    }     publicvoid setid (Integerid)  {       this.id  = id;    }     @Column (name= "name")     public string getname ()  {       returnname;    }     Publicvoid setname (Stringname)  {       this.name = name ;    }     @Column (name= "age")     public  Integer getage ()  {        returnage;     }    publicvoid setage (integerage)  {        this.age = age;    }}

@Entity @table (name= "T_group") publicclass Group {private Integer ID;        private String name;    @Id @GeneratedValue public Integer getId () {Returnid;    } publicvoid setId (integerid) {this.id = ID;    } @Column (name= "name") public String GetName () {returnname;    } publicvoid SetName (stringname) {this.name = name; }}

XML Configuration Methods

package csg.hibernate.entity; publicclass person {    private  integer id;    private string name;    private  integer age;    private group group;         public group getgroup ()  {       returngroup;     }    publicvoid setgroup (Groupgroup)  {        this.group = group;    }    public  integer getid ()  {       returnid;    }     publicvoid setid (Integerid)  {        This.id = id;    }    public string getname ()  {        returnname;    }    publicvoid setname (Stringname)  {       this.name = name;    }     public integer getage ()  {       returnage;     }    publicvoid setage (integerage)  {        this.age = age;    }}

package csg.hibernate.entity; publicclass group {     private Integer id;    private String name;         public integer getid ()  {        returnid;    }    publicvoid setid ( Integerid)  {       this.id = id;    }     public string getname ()  {        Returnname;    }    publicvoid setname (Stringname)  {        this.name = name;    }} 

<?xml version= "1.0"? ><! doctype hibernate-mapping public      "-//hibernate/hibernate mapping  dtd 3.0//en "    " HTTP://HIBERNATE.SOURCEFORGE.NET/HIBERNATE-MAPPING-3.0.DTD " >
<?xml version= "1.0"? ><! DOCTYPE hibernate-mapping Public "-//hibernate/hibernate mapping DTD 3.0//en" "Http://hibernate.sourceforge.net/hib Ernate-mapping-3.0.dtd ">

Here we use JUnit to test

publicclass junitest {privatestatic sessionfactory sessionfactory;          @BeforeClass     publicstaticvoid beforeclass ()  {        configuration cfg=new configuration ();        cfg.configure ();        sessionfactory= Cfg.buildsessionfactory ();    }        @Test      public  void add () {       try {            group group=new group ();            Session session =  Sessionfactory.getcurrentsession ();            Session.begintransaction ();           group.setname ("department");            Session.save (group);            person person=new  person ();            person.setage (; )           person.setname ("Zhang San");            person.setgroup (group);            session.save (person);            session.gettransaction (). Commit ();       } catch  ( Hibernateexception e) {           e.printstacktrace ();       }            }         @AfterClass     publicstaticvoid afterclass ()  {        sessionfactory.close ();     }}

Ok!


This article from "Promise always attached to the small wood 、、、" blog, please be sure to keep this source http://1936625305.blog.51cto.com/6410597/1568855
Hibernate's about many-to-one one-way association mappings