(This resource is provided and uploaded by the user "daihoujian", and all the downloaded beans will be returned to the user. This book is an effective textbook explaining design principles and the most common design patterns. It is intended to provide a quick and accurate teaching of design principles and design patterns for busy Java system designers. The book is divided into 55 chapters, each of which explains a programming pattern, its purpose, its structure, and what kind of situations it is suitable for. Each chapter is accompanied by a number of examples and exercises. Studying these examples and ending these exercises can help readers better understand the content. Most of the chapters are relatively independent, and the reader can open the book and start reading from any chapter. In order to meet the needs of readers of different degrees, this book provides some chapters marked as "topics". If you do not read these chapters, it will not affect the reading of the normative chapters of this book. After reading this book, readers can confidently use what they have learned in their own system design work, exchange object-oriented design experience with their partners, and have more harvests in office development. This book is suitable for Java programmers, architects and design pattern lovers. It is an effective self-study teaching material and manual for design principles and design patterns. This document includes the following attachments:)