hibernate屬性級別注解實例代碼

2024-07-13 10:13:16

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屬性級別注解

添加方式：

寫在屬性字段上面
寫在屬性的get訪問器的上面

@Id

必須，定義了映射到數據庫表的主鍵的屬性，一個實體類可以有一個或者多個屬性被映射為主鍵，可置于主鍵屬性或者getXxx()前，注意：如果有多個屬性定義為主鍵屬性，該實體類必須實現serializable接口

@SequenceGenerator
@GeneratedValue
@GeneratedValue(strategy=GenerationType,generator=""):可選，用于定義主鍵生成策略

strategy表示主鍵生成策略，取值有：

GenerationType.AUTO:根據底層數據庫自動選擇（默認）
GenerationType.INDENTITY:根據數據庫的Identity字段生成
GenerationType.SEQUENCE:使用Sequence來決定主鍵的取值
GenerationType.TABLE:使用指定表來決定主鍵取值，結合@TableGenerator使用

@Column

@Column-可將屬性映射到列，使用該注解來覆蓋默認值，@Column描述了數據庫表中該字段的詳細定義，這對于根據JPA
注解生成數據庫表結構的工具非常有作用。

常用屬性：

name:可選，表示數據庫表中該字段的名稱，默認情形屬性名稱一致
nullable:可選，表示該字段是否允許為null,默認為true
unique:可選，表示該字段是否為唯一標識，默認為false
length:可選，表示該字段的大小，僅對String類型的字段有效，默認值225，主鍵不能使用默認值
insertable:可選，表示在ORM框架執行插入操作時，該字段是否應出現INSERTRT語句中，默認為true
updateable:可選，表示在ORM框架執行更新操作時，該字段是否應該出現在UPDATE語句中，默認為true。對于已經創建
就不可以更改的字段，該屬性非常有用

@Embedded

@Embedded是注釋屬性的，表示該屬性的類是嵌入類。

注意：同時嵌入類也必須標注@Embeddable注解

@EmbeddedId

@EmbeddedId使用嵌入式主鍵類實現復合主鍵

注意：嵌入式主鍵類必須實現Serializable接口、必須有默認的public無參數的構造方法、必須覆蓋equals和hashCode方法

@Lob
@Version
@Basic
@Transient

可選，表示該屬性并非一個到數據庫表的字段的映射，ORM框架將忽略該屬性，如果一個屬性并非數據庫表的字段映射，就
務必將其標示為@Transient，否則ORM框架默認其注解為@Basic

實例：

hibernate.properties配置：

<!DOCTYPE hibernate-configuration PUBLIC   "-//Hibernate/Hibernate Configuration DTD 3.0//EN"   "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">  <hibernate-configuration>   <session-factory>   <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>     <!--      <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>     <property name="hibernate.connection.url">jdbc:mysql:///hibernate_struts_stumanager</property>      -->     <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>     <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mypage</property>               <property name="hibernate.connection.username">root</property>     <property name="hibernate.connection.password">root</property>     <property name="hibernate.show_sql">false</property>     <property name="hibernate.hbm2ddl.auto">create</property>   <!--   <property name="hibernate_current_session_context_class">thread</property> -->     <property name="current_session_context_class">thread</property>     <mapping class="com.entity.Students"/>   </session-factory> </hibernate-configuration>

實體類Student：

package com.entity; import java.io.Serializable; import java.util.Date; import javax.persistence.Column; import javax.persistence.Embedded; import javax.persistence.EmbeddedId; import javax.persistence.Entity;//JPA注解 import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; import javax.persistence.Transient; import org.hibernate.annotations.GenericGenerator; /*  * 學生實體類  */ //@Entity// //@Entity(name="t_students")//如果不添加名字，則默認與實體類名字相同，如果想要自行設置表明，就需要自己進行添加 @Entity @Table(name="t_students1",schema="mypage") public class Students implements Serializable{      @Id //    @GeneratedValue //    @GeneratedValue(strategy=GenerationType.AUTO)//與@GeneratedValue結果相同，字符串類型不能指定為AUTO類型 //     private int sid; //學號 //    @GeneratedValue(generator="sid") //    @GenericGenerator(name="sid",strategy="assigned") //    @Column(length=11) //    private String sid;      @EmbeddedId      private StudentPK pk; //    @Id //     //    @Column(length=11)      private String sname;//姓名      private String gender;//性別      private Date birthday;//出生日期      private String major;//專業      private Address add;      @Transient   //表示該字段不會被ORM映射到表里的字段      private double salary;//薪水      public Students(){      }     public Students(StudentPK pk, String sname, String gender,         Date date, String major,Address add,double salary) { //     super();       this.pk = pk;       this.sname = sname;       this.gender = gender;       this.birthday = date;       this.major = major;       this.add = add;       this.salary = salary;     }     public StudentPK getPk() {       return pk;     }     public void setPk(StudentPK pk) {       this.pk = pk;     }     public String getSname() {       return sname;     }     public void setSname(String sname) {       this.sname = sname;     }     public String getGender() {       return gender;     }     public void setGender(String gender) {       this.gender = gender;     }     public Date getBirthday() {       return birthday;     }     public void setBirthday(Date birthday) {       this.birthday = birthday;     }     public String getMajor() {       return major;     }     public void setMajor(String major) {       this.major = major;     }     public Address getAdd() {       return add;     }     public void setAdd(Address add) {       this.add = add;     }     public double getSalary() {       return salary;     }     public void setSalary(double salary) {       this.salary = salary;     }       }

StudentPK實體類：

package com.entity; import java.io.Serializable; import javax.persistence.Column; import javax.persistence.Embeddable; @Embeddable public class StudentPK implements Serializable{     /**    *    */   private static final long serialVersionUID = 1L;   @Column(length=18)   private String id;//身份證號   @Column(length=8)     private String sid;//學號     public StudentPK(){     }   public StudentPK(String id, String sid) {     this.id = id;     this.sid = sid;   }   public String getId() {     return id;   }   public void setId(String id) {     this.id = id;   }   public String getSid() {     return sid;   }   public void setSid(String sid) {     this.sid = sid;   }   @Override   public boolean equals(Object obj) {     // TODO Auto-generated method stub     return super.equals(obj);   }   @Override   public int hashCode() {     // TODO Auto-generated method stub     return super.hashCode();   } }

地址類：

package com.entity; import javax.persistence.Embeddable; import javax.persistence.Embedded; // 地址類 @Embeddable //表示是一個嵌入類，這個類的對象在另一個實體類中充當屬性  public class Address {    private String postCode;//郵編    private String address;//地址    private String phone;//聯系電話    public Address(){    }       public Address(String postCode, String address, String phone) {     this.postCode = postCode;     this.address = address;     this.phone = phone;   }    public String getPostCode() {     return postCode;   }   public void setPostCode(String postCode) {     this.postCode = postCode;   }   @Embedded   public String getAddress() {     return address;   }   public void setAddress(String address) {     this.address = address;   }   public String getPhone() {     return phone;   }   public void setPhone(String phone) {     this.phone = phone;   }     }

測試類：

package com.entity;  import java.util.Date; import java.util.EnumSet; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import org.hibernate.service.ServiceRegistry; import org.hibernate.service.ServiceRegistryBuilder; import org.hibernate.tool.hbm2ddl.SchemaExport; import org.junit.Test; public class TestStudents {   @Test     public void testShemaExport(){       //創建hibernate配置對象       Configuration config = new Configuration().configure();       //創建服務注冊對象       ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();       //生成SessionFactory       SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);       SchemaExport export = new SchemaExport(config);       export.create(true,true);     }   @Test   public void addStudents(){      //創建hibernate配置對象     Configuration config = new Configuration().configure();     //創建服務注冊對象     ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();     //生成SessionFactory     SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);     //創建會話     Session session = sessionFactory.getCurrentSession();     //創建事務     Transaction tx = session.beginTransaction();     Address add = new Address("700005","河南理工大學","15039117115");     StudentPK pk = new StudentPK("012345678912345678","55555555");     Students s = new Students(pk,"張三豐","男",new Date(),"太極拳",add,7899);     session.save(s);     tx.commit(); //   SchemaExport export = new SchemaExport(config); //    export.create(true,true);   } }

總結

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