@GeneratedValue used in conjunction with @GenericGenerator

@GeneratedValue action: Specify a primary key generation strategy.

@GenericGenerator effects: Customize primary key generation strategy.

    @Id
    @GeneratedValue(generator="_native")
    @GenericGenerator(name="_native",strategy="native")
    public int getId() {
        return id;
    }

The reference generator can @GeneratedValue name attribute value of the primary key generation strategy is defined @GenericGenerator, strategy generation strategy specified.