示例：一個類別（Category）下面有多個商品（Product），多個商品對應對應同一類別

?

Java代碼 ?

public?class?Category?{??

??

???????private?Integer?id;??

????private?String?name;??

????private?Set<Product>?products?=?new?HashSet<Product>();??

??

????//?getter?and?setter??

}?????

?

Java代碼 ?

public?class?Product?{??

??

????private?Integer?id;??

????private?String?name;??

????private?Double?price;??

????private?Category?category;??

??????

????//?getter?and?setter??

}??

用XML映射

Xml代碼 ?

<hibernate-mapping?package="org.monday.hibernate4.domain">??

????<class?name="Category"?table="tbl_category">??

????????<id?name="id">??

????????????<generator?class="identity"?/>??

????????</id>??

????????<property?name="name"?/>??

????????<set?name="products"?inverse="true">??

????????????<key?column="category_id"?/>??

????????????<one-to-many?class="Product"?/>??

????????</set>??

????</class>??

</hibernate-mapping>??

?

Xml代碼 ?

<hibernate-mapping?package="org.monday.hibernate4.domain">??

????<class?name="Product"?table="tbl_product">??

????????<id?name="id">??

????????????<generator?class="identity"?/>??

????????</id>??

????????<property?name="name"?/>??

????????<property?name="price"?/>??

????????<many-to-one?name="category"?class="Category"???

????????????column="category_id"?not-null="true"/>??

????</class>??

</hibernate-mapping>??

?用@Annotation映射

Java代碼 ?

@Entity??

@Table(name?=?"tbl_category")??

public?class?Category?{??

??

????@Id??

????@GeneratedValue(strategy?=?GenerationType.IDENTITY)??

????private?Integer?id;??

????private?String?name;??

????????//?使用泛型的話，targetEntity可以不制定??

????@OneToMany(mappedBy?=?"category")??

????private?Set<Product>?products?=?new?HashSet<Product>();??

??

????//?getter?and?setter??????

}?????

?

Java代碼 ?

@Entity??

@Table(name?=?"tbl_product")??

public?class?Product?{??

??

????@Id??

????@GeneratedValue(strategy?=?GenerationType.IDENTITY)??

????private?Integer?id;??

????private?String?name;??

????private?Double?price;??

??

????@ManyToOne??

????@JoinColumn(name?=?"category_id",?nullable?=?false)??

????private?Category?category;??

??

????//?getter?and?setter??????

}?????

?測試代碼

Java代碼 ?

Product?p?=?new?Product();??

p.setName("hibernate");??

p.setPrice(99.9);??

??

Category?c?=?new?Category();??

c.setName("book");??

c.getProducts().add(p);??

??

p.setCategory(c);??

??

session.save(c);?//?先插入一的一方??

session.save(p);??

? SQL schema

Sql代碼 ?

Hibernate:???

????create?table?tbl_category?(??

????????id?integer?not?null?auto_increment,??

????????name?varchar(255),??

????????primary?key?(id)??

????)??

Hibernate:???

????create?table?tbl_product?(??

????????id?integer?not?null?auto_increment,??

????????name?varchar(255),??

????????price?double?precision,??

????????category_id?integer,??

????????primary?key?(id)??

????)??

Hibernate:???

????alter?table?tbl_product???

????????add?index?FK2BA956E5535EE4C?(category_id),???

????????add?constraint?FK2BA956E5535EE4C???

????????foreign?key?(category_id)???

????????references?tbl_category?(id)??

Hibernate:???

????insert???

????into??

????????tbl_category??

????????(name)???

????values??

????????(?)??

Hibernate:???

????insert???

????into??

????????tbl_product??

????????(name,?price,?category_id)???

????values??

????????(?,??,??)??

??

總結

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