OOP设计模式

What design patterns are and the three main categories: creational, structural, and behavioral.

A class has one and only one instance, with Java and Go implementations including eager, lazy, DCL, static-inner-class, enum, mutex, and sync.Once approaches.

The proxy pattern adds functionality around an existing class or function without changing the original code, with static, dynamic, AOP, Go, and cache-proxy examples.

The template-method pattern applies when the overall algorithm steps are fixed while some parts vary, with Java and Go implementations and a combined template/factory/strategy example.

The factory-method pattern uses multiple factory classes and delays concrete product creation to subclasses.

The state pattern selects different processing logic according to the current state, with Java and Go examples.

The builder pattern constructs a complex object from many smaller parts; the builder creates the parts and the director assembles them.

The strategy pattern selects one of several algorithms for accomplishing the same task according to a type or context, with Java and Go examples.

The observer pattern broadcasts state changes from a subject to observers, with Java, Go, and application examples.

The decorator pattern adds new functionality to a class or function without changing the original code, with Java and Go examples.

The chain-of-responsibility pattern links handlers that can process the same type of request, with Java, Go, and filter-chain examples.

The adapter pattern is used to make an old-system interface compatible with a new interface, with Java and Go examples.

Prototype-pattern notes with UML, Java and Go clone examples, plus a generic DAO example that returns cloned data.

Abstract-factory notes showing related product families and a Go implementation with engines, wheels, factories, and a client.

Simple-factory notes in Java and Go, followed by a generic template-method + simple-factory + strategy example.

A short interview-style note on where singleton, prototype, factory, builder, facade, decorator, template method, state, strategy, and proxy patterns were used.

Flyweight-pattern notes with UML and a Java example using a chess-object pool.

Facade-pattern notes with UML plus Java and Go examples that wrap a complex process behind one interface.

Bridge-pattern notes for class hierarchies with multiple varying dimensions, with UML and a Java brand/device example.

Composite-pattern notes for tree-shaped whole/part structures, with Java and Go file-tree examples.

Mediator-pattern notes with UML, a Java department example, and a Go computer-component example.

Command-pattern notes with a Java Course example, command objects, and a command invoker.

Memento-pattern notes showing how to save an object's state and restore it later.

A minimal original note for the interpreter design pattern.

Visitor-pattern notes separating data structures from operations, with a Java course example.

Iterator-pattern notes showing Java and Go implementations for traversing aggregate objects.