Java 如何休眠验证可选值?

Java 如何休眠验证可选值?,java,regex,hibernate,hibernate-validator,Java,Regex,Hibernate,Hibernate Validator,如何创建一个值应遵循以下规则的hibernate验证注释: //should be: either empty, or if it has a value, it sould only be "A" or "B" @Pattern(regex = "???") String value; 如果是特定的,您应该实现自己的约束

如何创建一个值应遵循以下规则的hibernate验证注释:

//should be: either empty, or if it has a value, it sould only be "A" or "B"
@Pattern(regex = "???")
String value;

如果是特定的,您应该实现自己的约束