Hibernate 中的枚举 [英] Enumerations in Hibernate

问题描述

在 DAO 中有一个字段的值来自 Java 枚举通常很有用.一个典型的例子是登录 DAO，其中通常有一个字段将用户描述为NORMAL"或ADMIN".在 Hibernate 中，我将使用以下 2 个对象以(半)类型安全的方式表示这种关系:

It is often useful to have a field in a DAO whose value comes from a Java enumeration. A typical example is a login DAO where you usually have a field that characterises the user as "NORMAL" or "ADMIN". In Hibernate, I would use the following 2 objects to represent this relationship in a (semi-)typesafe way:

class User {
    String username;
    String passwd;
    UserType type;
}

class UserType {
    private enum Type {ADMIN, NORMAL};
    private String type;

    //Setters/Getters for Hibernate
    public void setType(String type);
    public String getType();

    //Setters/Getters for user
    public void setUserType(UserType.Type t);
    public UserType.Type getUserType();

    public static UserType fromType(UserType.Type t);
}

这行得通，但我发现 UserType 类很丑，为了存储几个值需要太多的官僚作风.理想情况下，Hibernate 应该直接支持枚举字段，并会创建一个额外的表来存储枚举值.

This works, but I find the UserType class ungly and requiring too much bureaucracy just to store a couple of values. Ideally, Hibernate should support enum fields directly and would create an extra table to store the enumeration values.

我的问题是:有没有办法在Hibernate中直接映射一个枚举类?如果不是，我代表枚举的模式是否足够好或者我错过了什么?人们还使用哪些其他模式?

My question is: Is there any way to directly map an enumeration class in Hibernate? If not, is my pattern for representing enumerations good enough or am I missing something? What other patterns do people use?

推荐答案

使用 hibernate 或 JPA 注释:

using hibernate or JPA annotations:

class User {
   @Enumerated(EnumType.STRING)
   UserType type
}

UserType 只是一个标准的 java 5 枚举.

UserType is just a standard java 5 enum.

我无法想象这仅限于注释，但我实际上不知道如何使用 hbm 文件来做到这一点.它可能非常依赖于版本，我猜但我很确定需要 hibernate 3.2+.

I can't imagine this is just limited to just annotations but I don't actually know how to do this with hbm files. It may be very version dependant, I'm guessing but I'm pretty sure that hibernate 3.2+ is required.

在 hbm 中是可能的，但有点乱，看看这个 论坛主题

edit: it is possible in a hbm, but is a little messy, have a look at this forum thread

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