在抽象工厂中插入数据库访问依赖关系是否好？

Question

我有一个抽象工厂类StudentValidatorFactory，它支持创建（基于指定参数）验证映射必须注入的各种StudentValidator类实例（请参阅下面的代码）。

public class StudentValidatorFactory{ 
    public static final int JUNIOR_STUDENT_TYPE = 1; 

    public static final int SENIOR_STUDENT_TYPE = 2; 

    public StudentValidator createStudentValidator(int studentType) throws StudentValidatorCreationException{ 
      Map<String,ValidationBean> validationMap = readValiationMapFromPersistentOrCachedStorage(studentType); 
      switch (studentType){ 
        case JUNIOR_STUDENT: 
         return new JuniorStudentValidator(validationMap); 
        case SENIOR_STUDENT: 
         return new SeniorStudentValidator(validationMap); 
      } 
    } 
} 

public interface StudentValidator{ 
     void validate(Student student) throws StudentValidationException; 
} 


public class JuniorStudentValidator{ 
    private Map<String, ValidationBean> validationMap;   

    public JuniorStudentValidator(Map<String,ValidationBean> validationMap){ 
     this.validationMap = validationMap; 
    } 

    public void validate(Student student) throws StudentValidationException{ 
     // make use of validation map for apply junior student related validations on the student 
    } 

} 


public class SeniorStudentValidator{ 
    private Map<String, ValidationBean> validationMap;   

    public SeniorStudentValidator(Map<String,ValidationBean> validationMap){ 
     this.validationMap = validationMap; 
    } 


    public void validate(Student student) throws StudentValidationException{ 
     // make use of validation map for apply senior student related validations on the student 
    } 

} 

我的问题是关于StudentValidatorFactory.createStudentValidator（INT studentType）方法是否读取从持久性存储（基于学生型）验证地图应创建方法内完成？否则说，工厂是否应该了解/依赖这些实施细节？

我很感激，如果有创建学生验证器时避免切换（studentType）语句的解决方案 - 我头顶的想法是有一个内部管理的地图并通过通过执行StudentValidator具体类实例化反思。

使用这种技术的优点是验证器更容易测试（通过依赖注入）。

Answer 1

提取物readValiationMapFromPersistentOrCachedStorage(studentType)处于分离服务接口StudentValidatorService和注射使用属性或构造器参数的在StudentValidatorFactory服务的实例：

public interface StudentValidatorService { 
    Map<String,ValidationBean> getValidationMap(int studentType); 
} 

public class StudentValidatorFactory{ 
    public static final int JUNIOR_STUDENT_TYPE = 1; 

    public static final int SENIOR_STUDENT_TYPE = 2; 

    public StudentValidatorFactory(StudentValidatorService studentValidatorService) { 
     this.studentValidatorService = studentValidatorService; 
    } 

    public StudentValidator createStudentValidator(int studentType) throws StudentValidatorCreationException{ 
      Map<String,ValidationBean> validationMap = studentValidatorService.getValidationMap(studentType); 
      switch (studentType){ 
        case JUNIOR_STUDENT: 
         return new JuniorStudentValidator(validationMap); 
        case SENIOR_STUDENT: 
         return new SeniorStudentValidator(validationMap); 
      } 
    } 
} 

现在，你可以通过编写数据库支持的StudentValidatorService的实现。或者你可以写一个模拟执行测试。该实现现在与使用情况分离。

---

要删除开关的情况下，使用一个枚举反其道而行：

public enum StudentType { 
    JUNIOR_STUDENT { 
     public StudentValidator getValidator(Map<String,ValidationBean> validationMap) { 
      return new JuniorStudentValidator(validationMap); 
     } 
    }, 
    SENIOR_STUDENT { 
     public StudentValidator getValidator(Map<String,ValidationBean> validationMap) { 
      return new SeniorStudentValidator(validationMap); 
     } 
    }; 

    public abstract StudentValidator getValidator(Map<String,ValidationBean> validationMap); 
} 

public class StudentValidatorFactory{ 

    public StudentValidatorFactory(StudentValidatorService studentValidatorService) { 
     this.studentValidatorService = studentValidatorService; 
    } 

    public StudentValidator createStudentValidator(StudentType studentType) throws StudentValidatorCreationException{ 
      Map<String,ValidationBean> validationMap = studentValidatorService.getValidationMap(studentType); 
      return studentType.getValidator(validationMap); 
    } 
}