head first design patterns pdf

Summary of common design patterns--responsibility chain model In the multithreaded programming model, the responsibility chain pattern is a common pattern, the responsibility chain model can decompose a task into small independent task units, so that the whole task at a glance. Take a crawler to crawl a page for example, assuming that the URL of the scheduling is not a crawler to manage, but there is a spec

facade façade that invokes the logic handler, what should we do if the logical handler has an exception?2. What do we need to do to deal with the results of logical processing to meet the rich foreground display needs?This one-on-one problem is based on the mining of the basic concepts of MVC. So, all of these questions need to be solved one by one when we write the program. Speaking of which, the questions raised at the beginning of this article should be answered: The framework is designed to

General principles in Design Patterns I. "open-closed" principle (OCP)The principle of open-closed principle is that a software entity should be open to extensions and closed to modifications.Advantages:New behaviors can be provided by extending existing software systems. The existing software modules, especially the most important abstraction layer modules, cannot be modified, which makes the sof

("-");}System.out.println (New String (SB) + this.getname ());For (company Company:acompanylist){Company.disp (depth + 2);}}}public class Compositepatterntest{public static void Main (string[] args){Company Parentcompany=new Concretecompany ("Anhui head Office");Company Suzhoubranchcompany=new Concretecompany ("Suzhou branch");Company Bengbubranchcompany=new Concretecompany ("Bengbu branch");Company Hefeioffice=new Office ("Hefei Office");Parentcompa

The observer pattern is simple to say, a pattern of newspaper-ordering. But in fact this Part I think is still very interesting, "Head first design mode" There are still some not read, but also because the understanding is not deep enough.The observer pattern consists of two components: The Observer and the subject.This code is the interface of the topic: Package Obeserver; Public Interface Subject { pu

The importance of design patterns in object-oriented objects. More in-depth understanding of object-oriented thinking, is conducive to the development of highly scalable programs. There is a "closing principle" in the PHP object-oriented: "Software entities should be open to extensions and closed to modifications." Popular saying: Add new class/interface, etc. come in line, modify not. 1. Factory mode In

to deal with the bug ... * in this way, the original technical director to handle the bug, now a layer of responsibility to the programmer to deal with the */handler1.sethandler ( HANDLER2); Handler2.sethandler (HANDLER3);/** * Through the printing results can be known: MyHandler instantiation will generate a series of mutually held objects (handler), forming a chain. */handler1.operator ();/** * "Note 2" The chain of responsibility is not linked list: The list has a