What are design patterns

In the Java framework, the difference between design patterns and architectural patterns is that design patterns define abstract solutions to common problems in software design, focusing on the interaction between classes and objects, such as factory patterns. Architectural patterns define the relationship between system structures and modules, focusing on the organization and interaction of system components, such as layered architecture.

TDD is used to write high-quality PHP code. The steps include: writing test cases, describing the expected functionality and making them fail. Write code so that only the test cases pass without excessive optimization or detailed design. After the test cases pass, optimize and refactor the code to improve readability, maintainability, and scalability.

The Guice framework applies a number of design patterns, including: Singleton pattern: ensuring that a class has only one instance through the @Singleton annotation. Factory method pattern: Create a factory method through the @Provides annotation and obtain the object instance during dependency injection. Strategy mode: Encapsulate the algorithm into different strategy classes and specify the specific strategy through the @Named annotation.

The SpringMVC framework uses the following design patterns: 1. Singleton mode: manages the Spring container; 2. Facade mode: coordinates controller, view and model interaction; 3. Strategy mode: selects a request handler based on the request; 4. Observer mode: publishes and listen for application events. These design patterns enhance the functionality and flexibility of SpringMVC, allowing developers to create efficient and maintainable applications.

The advantages of using design patterns in Java frameworks include: enhanced code readability, maintainability, and scalability. Disadvantages include complexity, performance overhead, and steep learning curve due to overuse. Practical case: Proxy mode is used to lazy load objects. Use design patterns wisely to take advantage of their advantages and minimize their disadvantages.

PHP design patterns provide known solutions to common problems in software development. Common pattern types include creational (such as factory method pattern), structural (such as decorator pattern) and behavioral (such as observer pattern). Design patterns are particularly useful when solving repetitive problems, improving maintainability, and promoting teamwork. In e-commerce systems, the observer pattern can realize automatic updates between shopping cart and order status. Overall, PHP design patterns are an important tool for creating robust, scalable, and maintainable applications.

Singleton, Factory and Observer are three commonly used design patterns in Python, which are used to solve the problems of object instantiation, creation of abstraction and dependency notification. 1. Singleton coordinates system operations by ensuring that a class has only one instance and provides global access points, such as configuration management; 2. Factory makes the code more flexible by encapsulating object creation logic, which facilitates the expansion of different types of object creation; 3. Observer allows objects to automatically notify dependent objects when state changes, and is suitable for event-driven systems such as GUI updates or logging systems. These patterns help improve the maintainability and scalability of your code.

The MyBatis framework widely applies design patterns, including: factory mode: creates SqlSessionFactory objects, manages database connections and queries; proxy mode: implements delayed loading and lazy loading to improve performance. Appearance mode: encapsulates database access and simplifies code maintenance. Among them, one-to-many relationship mapping can be implemented through the User and Order classes, Mapper interface and MapperXML configuration, using lazy loading and nested resultMap to optimize performance.