主表具有父类和子类的所有列。
The master table has all of the columns of the parent and all subclasses.
所有的子类将文本数据转换为数据值。
All the subclass does is convert the text data into a date value.
确保目标对象及其子类可以访问工厂方法。
Assure that the factory method is accessible to the target object and its subclasses.
优点和上面的“每个子类一张表”策略相似。
The pros are similar to the above "Table per Subclass" strategy.
它是专门目的只适用于这些子类。
It is specifically only intended to apply to those sub classes.
子类必须提供每个方法的实现。
A child class must provide an implementation for each method.
注意子类的索引在这里非常重要。
通过这种策略，每个子类都会拥有其自身的表。
这个类有许多可以从不同来源构造图像的子类。
This class has a number of subclasses that can construct images from different sources.
创建一个模拟对象类作为具体类中的一个子类。
Create a mock object class as a subclass of the concrete class.
变量类型应该匹配的原子类型。
策略1：每个子类一个表(Persons)。
但是无需注册即可发布实验性子类型。
However, you can designate experimental subtypes without registration.
哪些类别是顶级类别，哪些是子类别？
Which categories are the top-level categories, and which are sub-categories?
使用extends关键字创建子类。
我们已经见过几个父类和子类的例子了。
We've seen several examples of parent and child classes already.
它是Baseslider的直接子类。
这个方法还会将正在显示的子类清单置空。
This method also blanks out the list of subcategories being displayed.
可能每个产品子类型还有它自己的子类型。
It is possible that each product subtype may have its own subtypes.
正被删除的类型化表不能拥有任何子类型。
The typed table that is being dropped cannot have any subtables.
多类型示例指受类别和子类别约束的视图。
An example of multiple types is a view constrained by category and subcategory.
现在，我们可以以这个类为父类创建子类bean。
语言软接口与鸭子类型。
首先，创建CaseFolder类的一个子类。
The first thing to do is create a subclass of the CaseFolder class definition.
更具体地说，它是子类对相同消息做出不同反应的能力。
More specifically, it is the ability of subclasses to respond differently to the same messages.
有太多的替代方法可以轻易地为每种增强情形创建子类。
There are too many permutations to easily create subclasses for every enhancement scenario.
接下来的一种基本结构是子类型或row类型。
您永远不会创建它的实例——相反，您总是使用它的子类。
You never create an instance of it — instead, you always work with a subclass.
现在，您可以为这两个新的子类添加额外属性了。
Now you can add the extra attributes for the two new sub-classes.
永远不要直接实例化这个类，而是创建它的子类的一个实例。
You will never instantiate this class directly, but always create an instance of its subclass.
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