According to the Flink doc,
Flink recognizes a data type as a POJO type (and allows “by-name” field
referencing) if the following conditions are fulfilled:
- The class is public and standalone (no non-static inner class)
- The class has a public no-argument constructor
- All non-static, non-transient fields in the class (and all
superclasses) are either public (and non-final) or have a public getter-
and a setter- method that follows the Java beans naming conventions for
getters and setters.
PojoSerializer uses Java reflection to access an object's fields. One of
PojoSerializer's constructor calls setAccessible(true) for all fields.
for (int i = 0; i < numFields; i++) {
this.fields[i].setAccessible(true);
}
Then, to my knowledge, it can set a field regardless of the field's access
control(private, public,..).
However, its another constructor, called by PojoSerializerSnapshot, doesn't
call setAccessible(true). Does anyone know the reason why
setAccessible(true) is not called here? And why fields should be public or
have a public gettter- and setter- method?
Regards,
Naehee
