دانلود کتاب الگوهای طراحی خلاقانه در جاوا -طراحی نرم‌افزار انعطاف‌پذیر، مقیاس‌پذیر و قابل اعتماد

Welcome to your journey through Creational Design Patterns in Java. The concepts of design patterns are universal, and applying them in Java opens new opportunities for writing flexible, maintainable, and reusable code. You probably know that the design patterns became popular through the Gang of Four’s (GoF) classic book, Design Patterns: Elements of Reusable Object-Oriented Software (Addison-Wesley, 1994). The GoF book was published long before and focused on C++. On the contrary, since its birth in 1995, Java has been enriched with new features, and it is quite mature now. So, you may think: Do I still need these patterns? First, let me tell you that many of these patterns form the foundation of today’s programming practices. Next, design patterns require neither unusual language features nor amazing programming tricks to surprise others. If a supporting feature is not available, you may need to put some extra effort into achieving long-term flexibility and reusability. So, it’s no surprise that the GoF book remains a bestseller on Amazon. The classical GoF book cataloged 23 patterns into three categories —Creational, Structural, and Behavioral. They grouped five patterns: Abstract Factory, Factory Method, Prototype, Builder, and Singleton under the creational patterns. The creational patterns are about the creation of objects (yes, though the singleton restricts the number of objects, it is still creational). At a high level, these patterns abstract the instantiation process and help you make the systems independent from how their objects are composed, created, and represented. To illustrate, while implementing these patterns, you normally ask: “Where should I place the ‘new’ keyword in my application?” This decision can determine the degree of coupling of your classes. Over the period, the Abstract Factory became peripheral (see “Design Patterns 15 Years Later: An Interview with Erich Gamma, Richard Helm, and Ralph Johnson,” InformIT1). So, I did not discuss this pattern in this pocketbook. Instead, I included the discussion on the Dependency Injection (DI) pattern (instead of considering it as a single pattern, some developers and authors consider DI as a set of patterns and principles). It is interesting to note that later, one of the GoF authors, Ralph Johnson, acknowledged that the name of this pattern came out after their book was published. He also stated that they’d like to include DI in the second edition of their book (see JDD2015 – Twenty-one Years of Design Patterns (Ralph Johnson), YouTube2). This is why this pocketbook covers four GoF patterns and one non-GoF pattern.