Long Parameter List(过长参数列)---要重构的味道

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       int basePrice = _quantity * _itemPrice;
       int discountLevel;
       if (_quantity > 100) discountLevel = 2;
       else discountLevel = 1;
       double finalPrice = discountedPrice (basePrice, discountLevel);
       return finalPrice;
   }

   private double discountedPrice (int basePrice, int discountLevel) {
       if (discountLevel == 2) return basePrice * 0.1;
       else return basePrice * 0.05;
   }

       return discountedPrice ();
   }

   private double discountedPrice () {
       if (getDiscountLevel() == 2) return getBasePrice() * 0.1;
       else return getBasePrice() * 0.05;
   }

   private double getBasePrice() {
       return _quantity * _itemPrice;
   }

  class Room...
    boolean withinPlan(HeatingPlan plan) {
        int low = daysTempRange().getLow();
        int high = daysTempRange().getHigh();
        return plan.withinRange(low, high);
    }
  class HeatingPlan...
    boolean withinRange (int low, int high) {
        return (low >= _range.getLow() && high <= _range.getHigh());
    }
    private TempRange _range;

    boolean withinRange (TempRange roomRange) {
        return (roomRange.getLow() >= _range.getLow() && roomRange.getHigh() <= _range.getHigh());
    }
  class Room...
    boolean withinPlan(HeatingPlan plan) {
        int low = daysTempRange().getLow();
        int high = daysTempRange().getHigh();
        return plan.withinRange(daysTempRange());
    }

    boolean withinRange (TempRange roomRange) {
        return (_range.includes(roomRange));
    }
  class TempRange...
    boolean includes (TempRange arg) {
        return arg.getLow() >= this.getLow() && arg.getHigh() <= this.getHigh(); 

    double getFlowBetween (Date start, Date end) {
        double result = 0;
        Enumeration e = _entries.elements();
        while (e.hasMoreElements()) {
            Entry each = (Entry) e.nextElement();
            if (each.getDate().equals(start) ||
                each.getDate().equals(end) ||
                 (each.getDate().after(start) && each.getDate().before(end)))
            {
                result += each.getValue();
            }
        }
        return result;
    }
    private Vector _entries = new Vector();

  client code... 

    DateRange (Date start, Date end) {
        _start = start;
        _end = end;
    }
    Date getStart() {
        return _start;
    }
    Date getEnd() {
        return _end;
    }
    private final Date _start;
    private final Date _end;
  }

    double getFlowBetween (DateRange range) {
        double result = 0;
        Enumeration e = _entries.elements();
        while (e.hasMoreElements()) {
            Entry each = (Entry) e.nextElement();
            if (range.includes(each.getDate())) {
                result += each.getValue();
            }
        }
        return result;
    }

  class DateRange...
    boolean includes (Date arg) {
        return (arg.equals(_start) ||
                arg.equals(_end) ||
                 (arg.after(_start) && arg.before(_end)));
    }


参考资料：
 https://sourcemaking.com/refactoring/preserve-whole-object
 https://sourcemaking.com/refactoring/replace-parameter-with-method
 https://sourcemaking.com/refactoring/introduce-parameter-object

Long Parameter List(过长参数列)---要重构的味道

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原文地址：http://www.cnblogs.com/ttylinux/p/4575307.html