读书人
栏目▼

hibernate3 Annotation的施用(转)

发布时间： 2012-10-26 10:30:59 作者： rapoo

hibernate3 Annotation的使用(转)

注解映射必须满足两大条件：Hibernate3.2以上版本和JSEE 5。

@Entity 类注释，所有要持久化的类都要有

Java代码

?

  1. @Entity??
  2. public?class?Org??implements?java.io.Serializable?{ ??
  3. }??

?

@Entitypublic class Org implements java.io.Serializable {}

@Id 主键

Java代码

?

  1. @Id??
  2. ?????@GeneratedValue??
  3. ?????private?String?orgId; ??
  4. ?????private?String?orgName;??

?

@Id @GeneratedValue private String orgId; private String orgName;

@Column(name="...") 该属性对应表中的字段是什么，没有name表示一样

@Table 对象与表映射

@UniqueConstraint 唯一约束

@Version 方法和字段级，乐观锁用法，返回数字和timestamp，数字为首选

@Transient 暂态属性，表示不需要处理

@Basic 最基本的注释。有两个属性：fetch是否延迟加载，optional是否允许null

@Enumerated 枚举类型

@Temporal 日期转换。默认转换Timestamp

@Lob 通常与@Basic同时使用，提高访问速度。

@Embeddable 类级，表可嵌入的

@Embedded 方法字段级，表被嵌入的对象和@Embeddable一起使用

@AttributeOverrides 属性重写

@AttributeOverride 属性重写的内容和@AttributeOverrides一起嵌套使用

@SecondaryTables 多个表格映射

@SecondaryTable 定义辅助表格映射和@SecondaryTables一起嵌套使用

@GeneratedValue 标识符生成策略，默认Auto

表与表关系映射

@OneToOne：一对一映射。它包含五个属性：

targetEntity:关联的目标类

Cascade:持久化时的级联操作，默认没有

fetch:获取对象的方式，默认EAGER

Optional:目标对象是否允许为null，默认允许

mappedBy:定义双向关联中的从属类。

单向：

@JoinColumn:定义外键(主表会多一字段，做外键)

@OneToMany：一对多映射；@ManyToOne：多对一映射

单向一对多：

@OneToMany(cascade=CascadeType.ALL)

@JoinColumn(name="book_oid")/**book：表；oid：book表的主键；无name会按此规则自动生成*/

单向多对一：

@ManyToOne(cascade=CascadeType.ALL)

@JoinColumn(name="author_oid")

关联表格一对多：

@OneToMany(cascade=CascadeType.ALL)

@JoinTable(joinColumn={@JoinColumn(name="BOOK_OBJECT_OID")},inverseJoinColumns={@JoinColumn(name="AUTHER_OBJECT_OID")})

双向一对多或多对一：

不需要多一张表，只是使用mappedBy:使用在One一方，值为One方类名表示Many的从属类。

Java代码

?

  1. @Entity??
  2. public?class?Org??implements?java.io.Serializable?{ ??
  3. ??
  4. ??
  5. ????//?Fields???? ??
  6. ????@Id??
  7. ????@GeneratedValue??
  8. ?????private?String?orgId; ??
  9. ?????private?String?orgName; ??
  10. ?????@OneToMany(mappedBy?=?"org") ??
  11. ?????private?List<Department>?departments; ??
  12. ??
  13. ????//?Constructors ??
  14. ... ??
  15. ????//?Property?accessors ??
  16. ... ??
  17. }??

?

@Entitypublic class Org implements java.io.Serializable { // Fields @Id @GeneratedValue private String orgId; private String orgName; @OneToMany(mappedBy = "org") private List<Department> departments; // Constructors... // Property accessors...}

Java代码

?

  1. @Entity??
  2. public?class?Department??implements?java.io.Serializable?{ ??
  3. ??
  4. ??
  5. ????//?Fields???? ??
  6. ????@Id??
  7. ????@GeneratedValue??
  8. ?????private?String?id; ??
  9. ?????private?String?name; ??
  10. ?????@ManyToOne(fetch=FetchType.EAGER) ??
  11. ?????@JoinColumn(name="org_orgId") ??
  12. ?????private?Org?org; ??
  13. ?????@OneToMany(mappedBy?=?"department") ??
  14. ?????private?List<Employee>?employees; ??
  15. ??
  16. ????//?Constructors ??
  17. ??
  18. ????public?List<Employee>?getEmployees()?{ ??
  19. ????????return?employees; ??
  20. ????} ??
  21. ??
  22. ????public?void?setEmployees(List<Employee>?employees)?{ ??
  23. ????????this.employees?=?employees; ??
  24. ????} ??
  25. ??
  26. ????public?Org?getOrg()?{ ??
  27. ????????return?org; ??
  28. ????} ??
  29. ??
  30. ????public?void?setOrg(Org?org)?{ ??
  31. ????????this.org?=?org; ??
  32. ????} ??
  33. ??
  34. ????/**?default?constructor?*/??
  35. ?????????????. ??
  36. ?????????????. ??
  37. ?????????????. ??
  38. ???? ??
  39. }??

?

@Entitypublic class Department implements java.io.Serializable { // Fields @Id @GeneratedValue private String id; private String name; @ManyToOne(fetch=FetchType.EAGER) @JoinColumn(name="org_orgId") private Org org; @OneToMany(mappedBy = "department") private List<Employee> employees; // Constructors public List<Employee> getEmployees() { return employees; } public void setEmployees(List<Employee> employees) { this.employees = employees; } public Org getOrg() { return org; } public void setOrg(Org org) { this.org = org; } /** default constructor */ . . . }

Java代码

?

  1. @Entity??
  2. public?class?Employee??implements?java.io.Serializable?{ ??
  3. ??
  4. ??
  5. ????//?Fields???? ??
  6. ????@Id??
  7. ????@GeneratedValue??
  8. ?????private?String?employeeId; ??
  9. ?????private?String?employeeName; ??
  10. ?????private?String?passWord; ??
  11. ?????private?Integer?age; ??
  12. ?????private?Integer?sex; ??
  13. ?????@ManyToOne(fetch=FetchType.EAGER) ??
  14. ?????@JoinColumn(name="department_id") ??
  15. ?????private?Department?department; ??
  16. ??
  17. ????? ??
  18. ????public?Department?getDepartment()?{ ??
  19. ????????return?department; ??
  20. ????} ??
  21. ??
  22. ????public?void?setDepartment(Department?department)?{ ??
  23. ????????this.department?=?department; ??
  24. ????} ??
  25. ??
  26. ????/**?default?constructor?*/??
  27. ????... ??
  28. ????//?Property?accessors ??
  29. ????... ??
  30. }??

?

@Entitypublic class Employee implements java.io.Serializable { // Fields @Id @GeneratedValue private String employeeId; private String employeeName; private String passWord; private Integer age; private Integer sex; @ManyToOne(fetch=FetchType.EAGER) @JoinColumn(name="department_id") private Department department; public Department getDepartment() { return department; } public void setDepartment(Department department) { this.department = department; } /** default constructor */ ... // Property accessors ...}

双向多对多：@ManyToMany.单向多对多这里不在赘述（没有太多实际意义）

这个比较简单，看下代码就明白了：

Java代码

?

  1. @Entity??
  2. public?class?Book??implements?java.io.Serializable?{ ??
  3. ????@Id??
  4. ????private?int?id; ??
  5. ????private?String?name; ??
  6. ????private?float?money; ??
  7. ????@ManyToMany(cascade?=?CascadeType.ALL) ??
  8. ????private?List<Author>?authors; ??
  9. ???? ??
  10. ??
  11. ????public?List<Author>?getAuthors()?{ ??
  12. ????????return?authors; ??
  13. ????} ??
  14. ????public?void?setAuthors(List<Author>?authors)?{ ??
  15. ????????this.authors?=?authors; ??
  16. ????} ??
  17. ???? ??
  18. ?????????... ??
  19. }??

?

@Entitypublic class Book implements java.io.Serializable { @Id private int id; private String name; private float money; @ManyToMany(cascade = CascadeType.ALL) private List<Author> authors; public List<Author> getAuthors() { return authors; } public void setAuthors(List<Author> authors) { this.authors = authors; } ...}

?

Java代码

?

  1. @Entity??
  2. public?class?Author??implements?java.io.Serializable?{ ??
  3. ????@Id??
  4. ????private?int?id; ??
  5. ????private?String?name; ??
  6. ????private?int?age; ??
  7. ????@ManyToMany(mappedBy="authors") ??
  8. ????private?List<Book>?books; ??
  9. ???? ??
  10. ??
  11. ????public?List<Book>?getBooks()?{ ??
  12. ????????return?books; ??
  13. ????} ??
  14. ??
  15. ????public?void?setBooks(List<Book>?books)?{ ??
  16. ????????this.books?=?books; ??
  17. ????} ??
  18. ??
  19. ?????????... ??
  20. }??

?

@Entitypublic class Author implements java.io.Serializable { @Id private int id; private String name; private int age; @ManyToMany(mappedBy="authors") private List<Book> books; public List<Book> getBooks() { return books; } public void setBooks(List<Book> books) { this.books = books; } ...}

?

需要注意的是：注释最好加在属性上，不要加在get方法上，那样做有时候就会出错。比如:@ManyToMany的时候就会报错！

?

?

注意import javax.xx.Entity ，而不是org.hibernate.xx.Entity。??

Descn属性不存在于数据库中，用@Transient 注明??

------------------------------------------??

1,需要: Hibernate库文件,Hibernate Annotations库,ejb3-persstence.jar(Java 持久化API)??

sessionFactory=new AnnotationConfiguration().buildSessionFactory();??

------------------------------------------??

2,<bean id="sessionFactory" ),??

@NamedQuery(name="planeType.delete",query="delete from PlaneType where id=:id" )??

?}??

)??

------------------------------------------??

内嵌对象（组件）??

@Embedded({??

?? @AttributeOverride(name='iso2', column = @Column(name='bornIso2') ),??

?? @AttributeOverride(name='name', column = @Column(name='bornCountryName') )??

???????? })??

??? Country bornIn;??

??? ...??

}??

?

@Embeddable(access = AccessType.FIELD)??

public class Address implements Serializable {??

??? String city;??

??? Country nationality;??

}??

?

?

@Embeddable??

public class Country implements Serializable {??

??? private String iso2;??

??? private String name;??

?

??? public String getIso2() { return iso2; }??

??? public void setIso2(String iso2) { this.iso2 = iso2; }??

?

??? @Column(name='countryName')??

??? public String getName() { return name; }??

??? public void setName(String name) { this.name = name; }??

??? ...??

}??

------------------------------------------??

自定义的主键生成策略??

@javax.persistence.GeneratedIdTable(??

?? name='GEN_TABLE',??

? table = @Table(name='GENERATOR_TABLE'),??

??? pkColumnName = 'key',??

????? valueColumnName = 'hi'??

)??

?

@javax.persistence.TableGenerator(??

??? name='EMP_GEN',??

??? tableName='GEN_TABLE',??

??? pkColumnValue='EMP',??

??? allocationSize=20??

)??

@javax.persistence.SequenceGenerator(??

??? name='SEQ_GEN',??

??? sequenceName='my_sequence'??

)??

package org.hibernate.test.metadata;??

?

?

?

school和userMember是一对多关系

?

  1. import?javax.persistence.CascadeType;??
  2. import?javax.persistence.Column;??
  3. import?javax.persistence.Entity;??
  4. import?javax.persistence.FetchType;??
  5. import?javax.persistence.GeneratedValue;??
  6. import?javax.persistence.Id;??
  7. import?javax.persistence.OneToMany;??
  8. import?javax.persistence.Table;??
  9. import?javax.persistence.Temporal;??
  10. import?javax.persistence.TemporalType;??
  11. ??
  12. import?org.hibernate.annotations.Formula;??
  13. import?org.hibernate.annotations.GenericGenerator;??
  14. ??
  15. @Entity??
  16. @Table(name?=?"school_info")??
  17. public?class?SchoolInfo?implements?java.io.Serializable?{??
  18. ??
  19. ????@Id??
  20. ????@GeneratedValue(generator?=?"system-uuid")??
  21. ????@GenericGenerator(name?=?"system-uuid",?strategy?=?"uuid")??
  22. ????private?String?id;//hibernate的uuid机制,生成32为字符串??
  23. ??
  24. ????@Column(name?=?"actcodeId",?updatable?=?false,?nullable?=?true,?length?=?36)??
  25. ????private?String?actcodeId;??
  26. ??
  27. ????@Formula("select?COUNT(*)?from?school_info")??
  28. ????private?int?count;??
  29. ??
  30. ????@Temporal(TemporalType.TIMESTAMP)//不用set,hibernate会自动把当前时间写入??
  31. ????@Column(updatable?=?false,?length?=?20)??
  32. ????private?Date?createTime;??
  33. ??
  34. ????@Temporal(TemporalType.TIMESTAMP)??
  35. ????private?Date?updateTime;//?刚开始我默认insertable=false,但会读取出错提示如下:??
  36. ????//?Value?'0000-00-00'?can?not?be?represented?as?java.sql.Timestamp??
  37. ??
  38. ????// mappedBy="school"就相当于inverse=true,(mappedBy指定的是不需要维护关系的一端)??
  39. ????//?应该注意的是mappedBy值对应@ManyToOne标注的属性,我刚开始写成"schoolId",让我郁闷了好一会

    ?

    ?

  40. ????@OneToMany(mappedBy?=?"school",?cascade?=?CascadeType.ALL,?fetch?=?FetchType.EAGER,?targetEntity?=?UserMember.class)??
  41. ????//?用范性的话,就不用targetEntity了??
  42. ????private?List?users?=?new?ArrayList();??
  43. ??????
  44. }??

@GeneratedValue(strategy=GenerationType.AUTO)我们常用的自增长机制,我这里采用的是hibernate的uuid生成机制.

?

需要注意的是import javax.xx.Entity ，而不是org.hibernate.xx.Entity。

郁闷的是我上面用到@Formula,生成的sql竟然是'select COUNT(*) from school_info as formula0_ from school_info schoolinfo0_,当然不能执行了,寻求正解中~!!!!!!!!!

UserMember.java(前面引入的包已经贴过了,下面就不贴了)

?

?

  1. @Entity??
  2. @Table(name?=?"teacher_info")//实体类和数据库表名不一致时,才用这个??
  3. public?class?UserMember?implements?java.io.Serializable?{??
  4. ??
  5. ????@Id??
  6. ????@GeneratedValue(generator?=?"system-uuid")??
  7. ????@GenericGenerator(name?=?"system-uuid",?strategy?=?"uuid")??
  8. ????private?String?id;??
  9. ??
  10. ????@Column(updatable?=?false,?nullable?=?false,?length?=?20)??
  11. ????private?String?logonName;??
  12. ??????
  13. ????@Temporal(TemporalType.TIMESTAMP)??
  14. ????@Column(updatable?=?false,?length?=?20)??
  15. ????private?Date?createTime;??
  16. ??
  17. ????@Temporal(TemporalType.TIMESTAMP)??
  18. ????private?Date?updateTime;??
  19. ??
  20. ????@ManyToOne(cascade?=?{?CascadeType.MERGE?})??
  21. ????@JoinColumn(name?=?"schoolId")??
  22. ????private?SchoolInfo?school;??
  23. ????//注意该类就不用声明schoolId属性了,如果不用@JoinColumn指明关联的字段,hibernate默认会是school_id. ?

?

读书人网 >软件架构设计

热点推荐

触屏版 | 电脑版

读书人网 m.reader8.net