@Slf4j
@Component
public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        log.info("LoginInterceptor 目標方法執(zhí)行前執(zhí)行");
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        log.info("LoginInterceptor 目標方法執(zhí)行后執(zhí)行");
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        log.info("LoginInterceptor 視圖渲染完畢后執(zhí)行，最后執(zhí)行");
    }
}

@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Autowired
    private LoginInterceptor loginInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginInterceptor)
                .addPathPatterns("/**")
        ;
    }
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import springbook.interceptor.LoginInterceptor;
@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Autowired
    private LoginInterceptor loginInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginInterceptor)
                .addPathPatterns("/**")
                .excludePathPatterns("/user/login")
        ;
    }
}

@Slf4j
@Component
public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //true  表示放行   false表示攔截
        log.info("LoginInterceptor preHandle....");
        //獲取session, 并且判斷session中存儲的userinfo信息是否為空
        HttpSession session = request.getSession();
        UserInfo userInfo = (UserInfo) session.getAttribute(Constants.USER_SESSION_KEY);
        if (userInfo==null || userInfo.getId()<=0){
            //用戶未登錄
            response.setStatus(401);
            return false;
        }
        return true;
    }
}

@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Autowired
    private LoginInterceptor loginInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginInterceptor)
                .addPathPatterns("/**")
                .excludePathPatterns("/user/login")
                .excludePathPatterns("/css/**")
                .excludePathPatterns("/js/**")
                .excludePathPatterns("/pic/**")
                .excludePathPatterns("/**/*.html")
        ;
    }
}

protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
		HttpServletRequest processedRequest = request;
		HandlerExecutionChain mappedHandler = null;
		boolean multipartRequestParsed = false;
		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
		try {
			ModelAndView mv = null;
			Exception dispatchException = null;
			try {
				processedRequest = checkMultipart(request);
				multipartRequestParsed = (processedRequest != request);
				// Determine handler for the current request.
				mappedHandler = getHandler(processedRequest);
				if (mappedHandler == null) {
					noHandlerFound(processedRequest, response);
					return;
				}
				// Determine handler adapter for the current request.
				HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
				// Process last-modified header, if supported by the handler.
				String method = request.getMethod();
				boolean isGet = HttpMethod.GET.matches(method);
				if (isGet || HttpMethod.HEAD.matches(method)) {
					long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
					if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
						return;
					}
				}
				if (!mappedHandler.applyPreHandle(processedRequest, response)) {
					return;
				}
				// Actually invoke the handler.
				mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
				if (asyncManager.isConcurrentHandlingStarted()) {
					return;
				}
				applyDefaultViewName(processedRequest, mv);
				mappedHandler.applyPostHandle(processedRequest, response, mv);
			}
			catch (Exception ex) {
				dispatchException = ex;
			}
			catch (Throwable err) {
				// As of 4.3, we're processing Errors thrown from handler methods as well,
				// making them available for @ExceptionHandler methods and other scenarios.
				dispatchException = new ServletException("Handler dispatch failed: " + err, err);
			}
			processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
		}
		catch (Exception ex) {
			triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
		}
		catch (Throwable err) {
			triggerAfterCompletion(processedRequest, response, mappedHandler,
					new ServletException("Handler processing failed: " + err, err));
		}
		finally {
			if (asyncManager.isConcurrentHandlingStarted()) {
				// Instead of postHandle and afterCompletion
				if (mappedHandler != null) {
					mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
				}
			}
			else {
				// Clean up any resources used by a multipart request.
				if (multipartRequestParsed) {
					cleanupMultipart(processedRequest);
				}
			}
		}
	}

public class Log4j {
    public void log4jPrint(String message){
        System.out.println("我是Log4j, 打印日志內容為: "+message);
    }
}

public class Log4jAdapter implements Slf4jLog{
    private Log4j log4j;
    public Log4jAdapter(Log4j log4j) {
        this.log4j = log4j;
    }
    @Override
    public void log(String message) {
        log4j.log4jPrint("我是是適配器, 打印日志為: "+ message);
    }
}

public interface Slf4jLog {
    void log(String message);
}

public class Main {
    public static void main(String[] args) {
        Slf4jLog slf4jLog = new Log4jAdapter(new Log4j());
        slf4jLog.log("我是客戶端");
    }
}