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Hibernate annotation 使用筆記

@Entity????????????????????????? -- 聲明為一個實體bean???
?2

@Table(name = " promotion_info " )??? -- 為實體bean映射指定表(表名 = " promotion_info)???
?3

@Id????????????????????????????? -- 聲明了該實體bean的標識屬性???
?4

@GeneratedValue????????????????? -- 可以定義標識字段的生成策略.???
?5

@Transient?????????????????????? -- 將忽略這些字段和屬性,不用持久化到數據庫???
?6

@Column(name = " promotion_remark " ) -- 聲明列(字段名 = " promotion_total " )?屬性還包括(length = 200等)???
?7

@Temporal(TemporalType.TIMESTAMP) -- 聲明時間格式???
?8

@Enumerated????????????????????? -- 聲明枚舉???
?9

@Version???????????????????????? -- 聲明添加對樂觀鎖定的支持???
10

@OneToOne??????????????????????? -- 可以建立實體bean之間的一對一的關聯???
11

@OneToMany?????????????????????? -- 可以建立實體bean之間的一對多的關聯???
12

@ManyToOne?????????????????????? -- 可以建立實體bean之間的多對一的關聯???
13

@ManyToMany????????????????????? -- 可以建立實體bean之間的多對多的關聯???
14

@Formula???????????????????????? -- 一個SQL表達式，這種屬性是只讀的,不在數據庫生成屬性(可以使用sum、average、max等)???
15

@OrderBy???????????????????????? -- Many端某個字段排序(List)??
16

以上是基本常用注解，下面是例子說明

??1

@Entity??
??2

@Table(name="promotion_info")???
??3

public?class?Promotion?implements?Serializable?{???
??4

??
??5

????//AUTO--可以是identity類型的字段,或者sequence類型或者table類型,取決于不同的底層數據庫???
??6

????@Id????
??7

????@GeneratedValue(strategy?=?GenerationType.AUTO)???
??8

????//對于oracle想使用各自的Sequence:???
??9

????//@GeneratedValue(strategy?=?GenerationType.AUTO,generator="PROMOTION_SEQ")???
?10

????//@SequenceGenerator(name="PROMOTION_SEQ",sequenceName="PROMOTION_SEQ")???
?11

????private?Long?id;???
?12

??
?13

????@Column(name="group_start_amount")???
?14

????private?Integer?groupStartAmount=0;???
?15

???????
?16

????@Column(name="promotion_remark",length=200)???
?17

????//@Lob?如果是文章內容可以使用?只需要把length=200去掉就可以了???
?18

????private?String?remark;???
?19

????//DATE??????-?java.sql.Date???
?20

????//TIME??????-?java.sql.Time???
?21

????//TIMESTAMP?-?java.sql.Timestamp???
?22

????@Temporal(TemporalType.TIMESTAMP)???
?23

????@Column(name="start_time")???
?24

????private?Date?startTime;???
?25

??
?26

????//顯示0?隱藏1???
?27

????public?static?enum?DisplayType?{???
?28

????????顯示,隱藏???
?29

????}???
?30

????@Enumerated(value?=?EnumType.ORDINAL)//ORDINAL序數???
?31

????private?DisplayType?displayType?=?DisplayType.顯示;???
?32

??
?33

????@Version??
?34

????private?Integer?version;???
?35

??
?36

????//CascadeType.PERSIST???--?觸發級聯創建(create)???
?37

????//CascadeType.MERGE?????--?觸發級聯合并(update)???
?38

????//FetchType.LAZY????????--?延遲加載???
?39

????@ManyToOne(cascade?=?{CascadeType.PERSIST,CascadeType.MERGE},fetch?=?FetchType.LAZY)???
?40

????private?PromotionGroup?promotionGroup;???
?41

??
?42

????//單向ManyToMany???
?43

????//@JoinTable(關聯的表名)???
?44

????//joinColumns?--?promotion關聯的列的外鍵???
?45

????//inverseJoinColumns?--?largess?關聯列的外鍵???
?46

????@ManyToMany(cascade?=?{CascadeType.PERSIST,CascadeType.MERGE})???
?47

????@JoinTable(name="promotion_largess",joinColumns={@JoinColumn(name="promotion_id")},inverseJoinColumns={@JoinColumn(name="largess_id")})???
?48

????private?Set<Largess>?largess;????
?49

???????
?50

????@OneToMany(mappedBy="promotion",cascade?=?CascadeType.ALL)???
?51

????@OrderBy("quantity?asc")//item中的列表會根據quantity排序???
?52

????private?List<PromotionItem>?promotionItem;???
?53

??
?54

????//get?set?省略

.???
?55

????@Transient??
?56

????private?Long?hashcodeValue?=?null;???
?57

????public?synchronized?int?hashCode()?{???
?58

????????if(hashcodeValue?=?null)?{???
?59

????????????if(id?==?null)???
?60

????????????????hashcodeValue?=?new?Long(super.hashCode());???
?61

????????????else??
?62

????????????????hashcodeValue?=?id;???
?63

????????}???
?64

????????return?hashcodeValue.intValue();???
?65

????}???
?66

??
?67

????public?boolean?equals(Object?obj)?{???
?68

????????Promotion?other?=?(Promotion)?obj;???
?69

????????if(this?==?other)???
?70

????????????return?true;???
?71

????????if(this.id?==?null?||?other.id?==?null)???
?72

????????????return?false;???
?73

????????return?this.id.equals(other.id);???
?74

????}???
?75

??
?76

}???
?77

@Entity??
?78

@Table(name="promotion_group")???
?79

public?class?PromotionGroup?implements?Serializable?{???
?80

????@Id????
?81

????@GeneratedValue(strategy?=?GenerationType.AUTO)???
?82

????private?Long?id;???
?83

???????
?84

????//mappedBy的值"promotionGroup"指向owner(Promotion)端的關聯屬性,并且是雙向關系???
?85

????@OneToMany(mappedBy="promotionGroup",cascade=CascadeType.ALL)???
?86

????private?List<Promotion>?promotion;???
?87

??
?88

????//get?set?省略

.???
?89

}???
?90

@Entity??
?91

@Table(name="largess")???
?92

public?class?Largess?implements?Serializable?{???
?93

????@Id????
?94

????@GeneratedValue(strategy?=?GenerationType.AUTO)???
?95

????private?Long?id;???
?96

??
?97

????//1.sql語句中的字段和表名都應該和數據庫相應,而不是類中的字段,???
?98

????//若帶有參數如la.id=?id,這個=id才是類中屬性???
?99

????//2.操作字段一定要用別名???
100

????@Formula(select?max(la.id)?from?largess?as?la)???
101

????private?int?maxId;???
102

??
103

????@Formula(select?COUNT(la.id)?from?largess?la)???
104

????private?int?count;???
105

??
106

????@Transient??
107

????private?String?img???
108

??
109

????//get?set?省略

.???
110

}??
111

posted on 2010-08-18 17:32 duansky 閱讀(276) 評論(0) 編輯收藏所屬分類: Java

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Hibernate annotation 使用筆記