Interceptor拦截器如何记录日志

Interceptor拦截器记录日志通常是在网络请求或响应的过程中，对相关信息进行捕获和记录。以下是一个使用Java和Spring框架的示例，展示了如何创建一个拦截器来记录HTTP请求和响应的日志：

1. 首先，创建一个名为LoggingInterceptor的类，实现HandlerInterceptor接口：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoggingInterceptor implements HandlerInterceptor {
    private static final Logger logger = LoggerFactory.getLogger(LoggingInterceptor.class);

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        logger.info("Request URL: {}", request.getRequestURL());
        logger.info("HTTP Method: {}", request.getMethod());
        logger.info("IP Address: {}", request.getRemoteAddr());
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
        logger.info("Response Status: {}", response.getStatus());
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception) {
        if (exception != null) {
            logger.error("Exception occurred: ", exception);
        }
    }
}

2. 接下来，需要将LoggingInterceptor注册到Spring MVC的拦截器链中。创建一个名为WebConfig的类，实现WebMvcConfigurer接口，并重写addInterceptors方法：

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoggingInterceptor()).addPathPatterns("/**");
    }
}

现在，每当有HTTP请求发生时，LoggingInterceptor都会记录请求的URL、HTTP方法、IP地址等信息。在请求处理完成后，还会记录响应的状态码。如果在处理过程中发生异常，还会记录异常信息。

这只是一个简单的示例，你可以根据实际需求对其进行扩展，例如记录请求参数、响应数据等。