------------------Annotations-------------------@Entity//DECLARE an entity @Table (name= "table name")//with table mappings @Id//Specify the PRIMARY key @Column//Specify the column corresponding to the list
-----------Many-to-many annotation method programming step-----------First, we need to build three tables, a table of two JavaBean classes, and an intermediate table to build the table notes:
1, the corresponding JavaBean of the two tables must have a primary key, these two primary keys corresponding to the two foreign keys in the middle table, so as to establish the association
2. Examples of SQL statements are as follows: CREATE TABLE Student2 (ID number primary key NOT NULL, name varchar (30));
CREATE TABLE course (ID number primary key not NULL, name VARCHAR2 (30));
CREATE TABLE Student2_course (s_id number references Student2 (ID), c_id number references course (ID));
Second, the use of annotations (in front of the class note) 1, @Entity//placed in front of the JavaBean class to declare that this is an entity 2, @Table (name= "table name")//placed in @Entity, to declare the entity class corresponding to table 3, @Gener Icgenerator (name = "GenID", strategy = "increment")//declares how the primary key is generated
(Note Before method name) 4, @Id //declares a primary key, or it can be placed before the Get method 5, @Column//declares the column in the corresponding table of the variable 6, @GeneratedValu E (generator= "GenID") //and genericgenerator corresponding to use the value of the generator property inside the is the same value as the name in Genericgenerator 7, @ Manytomany //Statement Many-to-many relationship 8, @JoinTable (name= "Student2_course", &NBSP ; , &NB sp; joincolumns={@JoinColumn (name= "c_id")}, inversejoincolumns={@JoinColumn (name= "s_id")}) //n AME: corresponding intermediate table , &NB Sp , &NB Sp //joncolumns: The Inside reference The number is the array, so the table associated with this JavaBean primary key is declared with {} @joincolumn (name= "") foreign key &NBSP ; , &NB Sp , &NB Sp //inversejoincolum NS: In the same vein, declare the foreign key in the table with another JavaBean pair Specific code examples are as follows: &NBS P &nbsP , &NB Sp , &NB Sp //Class Coursu total @Entity @Table (name= "course") @GenericGenerator (name = "GenID", strategy = "increment") public c Lass Course { @Id @GeneratedValue (generator= "GenID") @Column (name= "id") private Long ID; @Column (name= "name") private String name; @ManyToMany @JoinTable (name= "Student2_course", joincolumns={@JoinColumn (name= "c_id")}, inversejoincolumns={@JoinColumn (name= "s_id")}) private set<student2> students = new hashset<student2> ();
Third, the configuration file Hibernate.cfg.xml need to add the mapping class in the configuration file <mapping class= "The path of the corresponding class/> <mapping class=" Com.ldl . domain1. Goodbean "/>
<! DOCTYPE hibernate-configuration Public "-//hibernate/hibernate configuration DTD 3.0//en" "Http://www.hibernate. Org/dtd/hibernate-configuration-3.0.dtd ">
<!-- 1, load Database driver, get database connection- <session-factory > <property name= "Hibernate.dialect" > Org.hibernate.dialect.oracle9idialect</property> <property name= "Hibernate.connection.driver_class" >oracle.jdbc.driver.OracleDriver</property> <property name= "Hibernate.connection.username" >scott</property> <property name= " Hibernate.connection.password ">tiger</property> <property name= "Hibernate.connection.url" >jdbc:oracle:thin: @localhost:1521:orcl</property> <!--169.254.146.196-- <!--show SQL, default to False- <property name= "Hibernate.show_sql" >true</ Property>
<!--adding mapping classes--<mapping class= "Com.ldl.domain1.GoodBean"/> <mapping class= "Com.ldl.domai N2. Course "/> <mapping class=" Com.ldl.domain2.Student2 "/>
</session-factory>
