深入浅出：Java设计模式之适配器模式(4)

添加时间:2007-11-07 原文发表:2007-11-07 人气:37

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    return validator.isValidAddress(address, zip, state);
}
private AddressValidator getValidator(String custType) {
    AddressValidator validator = null;
逆风者
    if (custType.equals(Customer.US)) {
      validator = new USAddress();
    }
    if (type.equals(Customer.CANADA)) {
      validator = new CAAddressAdapter();
    }
    return validator;
}
}//end of class
　　CAAddressAdapter设计和对AddressValidator（声明期望的接口）对象的多态调用使Customer可以利用接口不兼容CAAddress类提供的服务。

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　　Figure 20.4: Address Validation Application?Using Class Adapter

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　　Figure 20.5: Address Validation Message Flow?Using Class Adapter

　　作为对象适配器的地址适配器

　　当讨论以类适配器来实现地址适配器时，我们说客户类期望的AddressValidator接口是Java接口形式。现在，让我们假设客户类期望AddressValidator接口是抽象类而不是java接口。因为适配器CAAdapter必须提供抽象类AddressValidatro中声明的接口，适配器必须是AddressValidator抽象类的子类、实现抽象方法。

Listing 20.8: AddressValidator as an Abstract Class
public abstract class AddressValidator {
public abstract boolean isValidAddress(String inp_address,
     String inp_zip, String inp_state);
}//end of class
Listing 20.9: CAAddressAdapter Class
class CAAddressAdapter extends AddressValidator {
          …
          …
public CAAddressAdapter(CAAddress address) {
    objCAAddress = address;
}
public boolean isValidAddress(String inp_address,
     String inp_zip, String inp_state) {
          …
          …
}
}//end of class