怕忘記，把栗子貼上來

以Person類和Student類為例

public class Person {private Integer id;private String name;private int age;//省略setter、getter代碼 }

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public class Student extends Person {private String school;//省略setter、getter代碼 }

第一種方式：只有一張表的

直接貼映射文件內容

<hibernate-mapping package="com.zcd.exercise.subclass"><class name="Person" table="PERSONS" discriminator-value="PERSON"><id name="id" type="java.lang.Integer"><column name="ID" /><generator class="native" /></id><discriminator type="string"><column name="TYPE"></column></discriminator><property name="name" type="java.lang.String"><column name="NAME" /></property><property name="age" type="int"><column name="AGE" /></property><subclass name="Student" discriminator-value="STUDENT"><property name="school" type="string" column="SCHOOL"></property></subclass></class> </hibernate-mapping>

第二種方式：分兩張表存儲

<hibernate-mapping package="com.zcd.exercise.unionSubclass"><class name="Person" table="PERSONS"><id name="id" type="java.lang.Integer"><column name="ID" /><generator class="hilo" /></id><property name="name" type="java.lang.String"><column name="NAME" /></property><property name="age" type="int"><column name="AGE" /></property><union-subclass name="Student" table="STUDENTS"><property name="school" type="string"><column name="SCHOOL"></column></property></union-subclass></class> </hibernate-mapping>

?第三種方式：也是分兩張表但是會把子類特有的屬性單獨存放在一張表，也就是相當于把一條記錄拆開放在兩張表中。

<hibernate-mapping package="com.zcd.exercise.joinedSubclass"><class name="Person" table="PERSONS"><id name="id" type="java.lang.Integer"><column name="ID" /><generator class="native" /></id><property name="name" type="java.lang.String"><column name="NAME" /></property><property name="age" type="int"><column name="AGE" /></property><joined-subclass name="Student" table="STUDENTS"><key column="STUDENT_ID"></key><property name="school" type="string" column="SCHOOL"></property></joined-subclass></class> </hibernate-mapping>

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轉載于:https://www.cnblogs.com/GooPolaris/p/7920024.html

超強干貨來襲 云風專訪：近40年碼齡，通宵達旦的技術人生

總結

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