[Hibernate3-Summary] [section 3rd]: Today's summary-joint primary key

[Joint primary key]

>>>> Configuration method: XML:
1. Create a primary key entity class for studentpk separately in student

2. Configuration:

<composite-id name="studentPK">     <key-property name="name" column="username" />     <key-property name="nickname" column="nickname" /> </composite-id>

>>>> Annotation method: Annotation

1. Create a teacherpk primary key entity class separately in teacher
2. Annotation
** Annotation Method 1: [one annotation] ※common

<1>

@EmbeddedIdpublic TeacherPk getTeacherPk()

<2> the primary key class implements the serializable interface + overwrites the hashcode and equals methods.

TeacherPk implements Serializable{    @Override    public int hashCode()    @Override    public boolean equals(Object obj)}

** Annotation Method 2: [two annotations]

<1>

@Embeddablepublic class TeacherPk implements Serializable

@Idpublic TeacherPk getTeacherPk()

<2> same as above