Adapter pattern HandlerAdapter in Spring framework

In the Spring framework, the Adapter pattern is used to adapt different types of processors to a unified processor interface. Among them, HandlerAdapter is an interface used to define the specifications of processor adapters. The Spring framework provides multiple different types of HandlerAdapters to adapt to different types of processors. The function of a HandlerAdapter is to adapt processors (such as Controller, HttpRequestHandler, etc.) to a unified processor interface, so that different types of processors can be executed by calling unified processing methods through the interface. public interface HandlerAdapter { boolean supports(Object handler); ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception; } There are two methods defined in the HandlerAdapter interface: -Supports (Object handler): Determine whether the adapter supports the given processor type. -Handle (HttpServletRequest request, HttpServletResponse response, Object handler): Process the request and execute the adapted processor. The HandlerAdapter in Spring implements these two methods, which are used to adapt different types of processors to a unified processor interface. Spring provides multiple implementation classes for HandlerAdapters, such as RequestMappingHandlerAdapters, SimpleControllerHandlerAdapters, etc., to adapt to different types of processors. The specific code implementation is as follows: public class SimpleControllerHandlerAdapter implements HandlerAdapter { public boolean supports(Object handler) { return (handler instanceof SimpleController); } public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { return ((SimpleController) handler).handleRequest(request, response); } } The above code is an implementation of SimpleControllerHandlerAdapter, which is adapted to processors that implement the SimpleController interface. Its supports method determines whether the given processor is of type SimpleController, and the handle method calls the handler's handleRequest method to process the request. Summary: The Adapter pattern is widely used in the Spring framework, especially in the process of processing requests. The HandlerAdapter pattern enables the framework to adapt to different types of processors and handle requests through a unified interface. This can reduce the code complexity of the framework, improve code reusability and flexibility. With the support of HandlerAdapters, the Spring framework can adapt to various types of processors and manage and schedule them uniformly.