JPA主键映射

 1、自动增长主键配置：

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;

适用范围：用于Mysql主键自动增长的情况。

2、SequenceGenerator 配置

@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="personPKGen")
@SequenceGenerator(name="personPKGen",sequenceName="PERSON_PK_GEN",allocationSize=1)
private int id;

备注：

 SequenceGenerator.name：主键生成器的名称，提供给GeneratedValue.generator属性引用；

SequenceGenerator.sequenceName：对应Oracle数据库的序列名称；

SequenceGenerator.allocationSize：增长值，如果不设定，默认是50；

适用范围：用于Oralcle数据库的序列。

3、TableGenerator配置

@Id
@GeneratedValue(strategy=GenerationType.TABLE, generator="personPKGen")
@TableGenerator(name="personPKGen", table="id_generator", pkColumnName="gen_name",pkColumnValue="person_PK", valueColumnName="gen_value",allocationSize=1)

备注：

 TableGenerator.table：对应主键生成表；

 TableGenerator.pkColumnName：主键列名；

 TableGenerator.pkColumnValue：主键列值；

 

4、复合主键配置    

      （1）定义主键类

public class Name implements Serializable {    
 private String firstName;     
 private String lastName;     
 public Name() {   
  }
 public Name(String firstName, String lastName) {
         this.firstName = firstName;
         this.lastName = lastName;
     }          
 public String getFirstName() {
         return firstName;
     }    
 public void setFirstName(String firstName) {
         this.firstName = firstName;
     }    
 public String getLastName() {
         return lastName;
     }    
 public void setLastName(String lastName) {
         this.lastName = lastName;
     }      //重写hashCode方法    
 public int hashCode() {
         return this.firstName.hashCode() + this.lastName.hashCode();
     }     //重写equals方法    
 public boolean equals(Object obj) {
         if (this == obj) {
         return true;
     }
     if (this.getClass() == obj.getClass()) {
         Name name = (Name) obj;
         if(name.getFirstName().equals(this.getFirstName())&& name.getLastName().equals(this.getLastName())) {
             return true;
         }
     }
     return false;
 }
}

 

      （2）可以通过@IdClass和@Id注释的方式配置主键，或者通过 @EmbededId方式配置主键。

• @IdClass 与 @Id配置主键：

  @Entity
  @Table(name = "person_embedded_id")
  @IdClass(Name.class)
  public class Person {
   
   //多个@Id配置复合ID
   @Id
   @Column(name="first_name", nullable=false, length=64)
   private String firstName;
   
   @Id
   @Column(name="last_name", nullable=false, length=64)
   private String lastName; 
    @Temporal(value = TemporalType.DATE)
   private Date birthday;
   
   @Column(length=64)
   private String email;
   
   @Column(length=11)
   private String phone;
   
   @Column(name="home_address", length=256)
   private String homeAddress; @Column(name="company_address", length=256)
   private String companyAddress; public Person() {
   } 
   public String getFirstName() {
    return firstName;
   }
   public void setFirstName(String firstName) {
    this.firstName = firstName;
   }
   public String getLastName() {
    return lastName;
   }
   public void setLastName(String lastName) {
    this.lastName = lastName;
   }
   public Date getBirthday() {
    return birthday;
   }
   
   public void setBirthday(Date birthday){
    this.birthday = birthday;
   }
   public String getEmail() {
    return email;
   }
   public void setEmail(String email) {
    this.email = email;
   }
   public String getPhone() {
    return phone;
   }
   public void setPhone(String phone) {
    this.phone = phone;
   }
   public String getHomeAddress() {
    return homeAddress;
   }
   public void setHomeAddress(String homeAddress) {
    this.homeAddress = homeAddress;
   }
   public String getCompanyAddress() {
    return companyAddress;
   }
   public void setCompanyAddress(String companyAddress) {
    this.companyAddress = companyAddress;
   }
  }
  

  
  
• @EmbeddedId配置

  @Entity
  @Table(name = "person_embedded_id")
  public class Person { 
   
   @EmbeddedId
   @AttributeOverrides({
    @AttributeOverride(name="firstName", column=@Column(name="first_name", nullable=false, length=64)),
    @AttributeOverride(name="lastName", column=@Column(name="last_name", nullable=false, length=64))
   })
   private Name name;
    @Temporal(value = TemporalType.DATE)
   private Date birthday;
   
   @Column(length=64)
   private String email;
   
   @Column(length=11)
   private String phone;
   
   @Column(name="home_address", length=256)
   private String homeAddress; @Column(name="company_address", length=256)
   private String companyAddress; public Person() {
   } 
   public Name getName() {
    return name;
   }
   public void setName(Name name) {
    this.name = name;
   }
   
   public Date getBirthday() {
    return birthday;
   }
   
   public void setBirthday(Date birthday){
    this.birthday = birthday;
   }
   public String getEmail() {
    return email;
   }
   public void setEmail(String email) {
    this.email = email;
   }
   public String getPhone() {
    return phone;
   }
   public void setPhone(String phone) {
    this.phone = phone;
   }
   public String getHomeAddress() {
    return homeAddress;
   }
   public void setHomeAddress(String homeAddress) {
    this.homeAddress = homeAddress;
   }
   public String getCompanyAddress() {
    return companyAddress;
   }
   public void setCompanyAddress(String companyAddress) {
    this.companyAddress = companyAddress;
   }
  }