The factory pattern is a design pattern that provides an interface for creating objects, but the instantiation process of specific objects is completed by the factory class. In Python, you can use the simple factory pattern or the Factory method pattern pattern to implement the factory pattern. The following is an example code that uses the simple factory mode: ```python class Dog: def __init__(self, name): self.name = name def speak(self): return "Woof!" class Cat: def __init__(self, name): self.name = name def speak(self): return "Meow!" class AnimalFactory: def create_animal(self, animal_type, name): if animal_type == "dog": return Dog(name) elif animal_type == "cat": return Cat(name) else: raise ValueError("Invalid animal type.") factory = AnimalFactory() animal1 = factory.create_animal("dog", "Buddy") animal2 = factory.create_animal("cat", "Milo") print(animal1.name) # Output: Buddy print(animal1.speak()) # Output: Woof! print(animal2.name) # Output: Milo print(animal2.speak()) # Output: Meow! ``` In the above code, we defined two specific animal classes, 'Dog' and 'Cat', and both implemented the 'speak' method` The AnimalFactory class is a simple factory class that has a 'create'_ The 'animal' method, based on the parameter 'animal'_ Type 'to determine which specific animal object to create. By calling 'factory. create'_ The 'animal' method allows us to create different types of animal objects as needed. In this way, we can encapsulate the process of creating objects in the factory class, and users only need to call the methods of the factory class without worrying about the instantiation process of specific objects. This is a simple example of using Python to implement the factory pattern. In practical applications, the factory pattern can provide a more flexible way to create objects, and can well follow the Open–closed principle.

There are two implementation methods for the factory pattern in the Spring framework: BeanFactory and Application Context. 1. BeanFactory: BeanFactory is the infrastructure of the Spring framework, which is an implementation of the factory pattern used to manage and retrieve bean objects in applications. BeanFactory provides the following features: -Instantiating objects: Instantiating bean objects through configuration files or annotations; -Manage objects: Manage the lifecycle of bean objects, such as setting property values, calling initialization methods, and destroying methods for bean objects; -Get Object: Retrieve the corresponding Bean object based on its name or type. The core methods of the BeanFactory interface include: getBean (String name), getBean (Class<T>requiredType), and containsBean (String name). 2. Application Context: Application Context is a sub interface of BeanFactory, which has been extended and enhanced based on BeanFactory. Compared to BeanFactory, Application Context provides more functions and features, including: -Internationalization support: providing support for multilingual environments; -Event propagation: supports event publishing and monitoring; -Resource management: Provide unified resource management, such as access to resources such as file systems, class paths, and URLs; -AOP support: Supports facet oriented programming. The core implementation classes of Application Context are AnnotationConfigApplication Context and ClassPathXmlApplication Context, which are used for application environments based on annotation and XML configuration, respectively. The following is a complete source code example of the factory mode in the Spring framework: 1. Usage example of BeanFactory: ```java import org.springframework.beans.factory.BeanFactory; import org.springframework.beans.factory.xml.XmlBeanFactory; import org.springframework.core.io.ClassPathResource; public class BeanFactoryExample { public static void main(String[] args) { //Load Configuration File BeanFactory factory = new XmlBeanFactory(new ClassPathResource("applicationContext.xml")); //Get bean object HelloWorld helloWorld = (HelloWorld) factory.getBean("helloWorld"); System.out.println(helloWorld.getMessage()); } } ``` 2. Usage examples of Application Context: ```java import org.springframework.context.ApplicationContext; import org.springframework.context.annotation.AnnotationConfigApplicationContext; public class ApplicationContextExample { public static void main(String[] args) { //Load Configuration Class ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class); //Get bean object HelloWorld helloWorld = context.getBean(HelloWorld.class); System.out.println(helloWorld.getMessage()); } } ``` Summary: The factory pattern in the Spring framework provides powerful Dependency injection and bean management functions through BeanFactory and ApplicationContext. BeanFactory is the infrastructure of Spring, providing basic bean management functions; Application Context has been extended on the basis of BeanFactory, providing more features and functions, such as internationalization support, event propagation, and AOP support. Developers can choose suitable implementation methods based on specific needs.

The factory pattern in the MyBatis framework mainly involves two key classes: SqlSessionFactory and SqlSession. 1. SqlSessionFactory: This class is the entry point for the MyBatis framework, used to create SqlSession objects. SqlSessionFactory uses factory mode, hiding the complexity of creating SqlSessions. The SqlSessionFactory interface provides multiple methods to create SqlSession objects, including openSession() and openSession (boolean autoCommit). 2. SqlSession: SqlSession is the main interface for interacting with databases in the MyBatis framework. It provides a series of methods for developers to operate databases, such as adding, deleting, modifying, and querying. SqlSession is used to execute SQL statements and return results. SqlSession also provides support for transactions, which can be committed or rolled back through the commit () and rollback () methods. The following is the complete source code for SqlSessionFactory and SqlSession in the MyBatis framework: 1. SqlSessionFactory interface code: ```java public interface SqlSessionFactory { SqlSession openSession(); SqlSession openSession(boolean autoCommit); //Other methods } ``` 2. SqlSession interface code: ```java public interface SqlSession extends Closeable { //CRUD Method void commit(); void rollback(); //Other methods } ``` Summary: The application of factory mode in the MyBatis framework is mainly reflected in the creation process of SqlSessionFactory. SqlSessionFactory encapsulates the complex logic of creating SqlSession objects, allowing developers to obtain SqlSession instances by simply calling the openSession() method. SqlSession is the entry point for developers to interact with databases, encapsulating a series of database operation methods and providing transaction support. Through the factory mode, the MyBatis framework shields the complexity of accessing the underlying database, allowing developers to operate the database more conveniently. At the same time, the factory mode also provides scalability, allowing for flexible creation of SqlSession instances based on specific business needs.