使用ORMLite将枚举集合存储在数据库中

Question

我正在尝试使用ORMLite将枚举集合保存在数据库中。因此，在创建Dao时，我得到no-args构造函数错误

我试过创建默认的包构造函数，但它没有帮助 - 我认为ORMLite需要公共构造函数，但枚举不能拥有它。

我的枚举看起来像这样（分开的.java文件）

enum RankPermission {
  @DatabaseField(dataType=DataType.ENUM_TO_STRING)
  ALL,
  //...
  ;

  RankPermission() {}
}

另一个班级的收藏是

@DatabaseTable
class Rank {
  @ForeignCollectionField
  Collection<RankPermission> permissions;

  public Rank() {}
}

Dao创造和我得到的错误

DaoManager.createDao(conn, Rank.class);

        [23:31:12 ERROR]: Can't find a no-arg constructor for class package.core.rank.RankPermission
        java.lang.IllegalArgumentException: Can't find a no-arg constructor for class package.core.rank.RankPermission
        at com.j256.ormlite.table.DatabaseTableConfig.findNoArgConstructor(DatabaseTableConfig.java:229) ~[?:?]
        at com.j256.ormlite.table.DatabaseTableConfig.getConstructor(DatabaseTableConfig.java:154) ~[?:?]
        at com.j256.ormlite.table.TableInfo.<init>(TableInfo.java:96) ~[?:?]
        at com.j256.ormlite.table.TableInfo.<init>(TableInfo.java:54) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl.initialize(BaseDaoImpl.java:156) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl.<init>(BaseDaoImpl.java:133) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl.<init>(BaseDaoImpl.java:112) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl$5.<init>(BaseDaoImpl.java:1044) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl.createDao(BaseDaoImpl.java:1044) ~[?:?]
        at com.j256.ormlite.dao.DaoManager.createDao(DaoManager.java:70) ~[?:?]
        at com.j256.ormlite.field.FieldType.configDaoInformation(FieldType.java:392) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl.initialize(BaseDaoImpl.java:206) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl.<init>(BaseDaoImpl.java:133) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl.<init>(BaseDaoImpl.java:112) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl$5.<init>(BaseDaoImpl.java:1044) ~[?:?]
        at com.j256.ormlite.dao.BaseDaoImpl.createDao(BaseDaoImpl.java:1044) ~[?:?]
        at com.j256.ormlite.dao.DaoManager.createDao(DaoManager.java:70) ~[?:?]
        at package.storage.yaml.db.DatabaseConnector.initDaos(DatabaseConnector.java:152) ~[?:?]

我想以枚举形式保存这个集合，因为它更舒服

Answer 1

为了解决这个问题，我刚刚使用了java.util包中的任何Collection并设置了@DatabaseField(dataType=DataType.SERIALIZABLE)注释而不是@ForeignCollectionField来保存序列化数据，所以现在代码是

class Rank {
    @DatabaseField(dataType=DataType.SERIALIZABLE)
    private HashSet<RankPermission> permissions = new HashSet<>();
}

将HashSet类型设置为字段非常重要，因为ORMLite不会检测Set上的可序列化接口。