Mô hình cấu trúc quy định việc tổ chức các lớp học và các đối tượng. Những mô hình có liên quan với các lớp kế thừa từ nhau hoặc làm thế nào họ được cấu tạo từ các lớp khác. Phổ biến các mô hình cấu trúc bao gồm Adapter, Proxy, và các mẫu trang trí. Những mô hình tương tự như trong họ giới thiệu một mức độ gián tiếp giữa | Presented by developerWorks your source for great tutorials developerWorks Section 5. Structural patterns Overview Structural patterns prescribe the organization of classes and objects. These patterns are concerned with how classes inherit from each other or how they are composed from other classes. Common structural patterns include Adapter Proxy and Decorator patterns. These patterns are similar in that they introduce a level of indirection between a client class and a class it wants to use. Their intents are different however. Adapter uses indirection to modify the interface of a class to make it easier for a client class to use it. Decorator uses indirection to add behavior to a class without unduly affecting the client class. Proxy uses indirection to transparently provide a stand-in for another class. The Adapter pattern The Adapter pattern is typically used to allow the reuse of a class that is similar but not the same as the class the client class would like to see. Typically the original class is capable of supporting the behavior the client class needs but does not have the interface the client class expects and it is not possible or practical to alter the original class. Perhaps the source code is not available or it is used elsewhere and changing the interface is inappropriate. Here is an example that wraps Oldciass so a client class can call it using a method NewMethod defined in Newlnterface public class OldClassAdapter implements NewInterface private OldClass ref public OldClassAdapter OldClass oc ref oc public void NewMethod Java design patterns 101 Page 12 of 22 Presented by developerWorks your source for great tutorials developerWorks The Proxy and Decorator patterns A Proxy is a direct stand-in for another class and it typically has the same interface as that class because it implements a common interface or an abstract class. The client object is not aware that it is using a proxy. A Proxy is used when access to the
