Hibernate实体对象继承的三种方法

@Entity 
@Inheritance(strategy=InheritanceType.SINGLE_TABLE) 
@DiscriminatorColumn(name="discriminator", discriminatorType=DiscriminatorType.STRING)//表示区分不同的对象的字段名 
@DiscriminatorValue("person")//用来表示该对象是何种对象的,即区分器 
public class Parent { 
  private int id; 
  private String name; 
   
  @Id 
  @GeneratedValue 
  public int getId() { 
    return id; 
  } 
  public void setId(int id) { 
    this.id = id; 
  } 
  public String getName() { 
    return name; 
  } 
  public void setName(String name) { 
    this.name = name; 
  } 
 
} 
 
@Entity 
@DiscriminatorValue("child1") 
public class Child1 extends Parent { 
  private String email; 
 
  public String getEmail() { 
    return title; 
  } 
 
  public void setEmail(String email) { 
    this.email = email; 
  } 
 
   
} 
 
 
 
@Entity 
@DiscriminatorValue("child2") 
public class Child2 extends Parent { 
   
  private String address; 
 
  public String getAddress() { 
    return score; 
  } 
 
  public void setAddress(String address) { 
    this.address = address; 
  } 
   
}  
    

@Entity 
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS) 
@TableGenerator(    //一个类一张表，最重要的是要保证它们的id由一个生成器产生，@TableGenerator就是为了控制这个的 
    name="t_gen", 
    table="t_gen_table", 
    pkColumnName="t_pk", 
    valueColumnName="t_value", 
    pkColumnValue="person_pk", 
    initialValue=1, 
    allocationSize=1 
    ) 
public class Parent { 
  private int id; 
  private String name; 
   
  @Id 
  @GeneratedValue(generator="t_gen", strategy=GenerationType.TABLE)//这个就是用表生成器生成的，用同一个生成器就可以控制它们的id不重复 
  public int getId() { 
    return id; 
  } 
  public void setId(int id) { 
    this.id = id; 
  } 
  public String getName() { 
    return name; 
  } 
  public void setName(String name) { 
    this.name = name; 
  } 
 
} 
 
 
@Entity 
public class Child2 extends Parent { 
   
  private String address; 
 
  public String getAddress() { 
    return score; 
  } 
 
  public void setAddress(String address) { 
    this.address = address; 
  } 
   
} 
 
 
@Entity 
public class Child1 extends Parent { 
  private String email; 
 
  public String getEmail() { 
    return title; 
  } 
 
  public void setEmail(String email) { 
    this.email = email; 
  } 
 
   
} 

@Entity 
@Inheritance(strategy=InheritanceType.JOINED) 
 
public class Parent { 
  private int id; 
  private String name; 
   
  @Id 
  @GeneratedValue 
  public int getId() { 
    return id; 
  } 
  public void setId(int id) { 
    this.id = id; 
  } 
  public String getName() { 
    return name; 
  } 
  public void setName(String name) { 
    this.name = name; 
  } 
 
} 
 
@Entity 
public class Child2 extends Parent { 
   
  private String address; 
 
  public String getAddress() { 
    return score; 
  } 
 
  public void setAddress(String address) { 
    this.address = address; 
  } 
   
} 
 
 
@Entity 
public class Child1 extends Parent { 
  private String email; 
 
  public String getEmail() { 
    return title; 
  } 
 
  public void setEmail(String email) { 
    this.email = email; 
  } 
 
   
}