如何在Java中拦截网络请求数据 Java实现中间件拦截机制

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

public class MyRequestInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        long startTime = System.currentTimeMillis();
        request.setAttribute("startTime", startTime); // 记录请求开始时间
        System.out.println("请求进入拦截器: " + request.getRequestURI());
        // 假设这里做个简单的权限判断
        String userToken = request.getHeader("X-Auth-Token");
        if (userToken == null || !userToken.equals("valid-token")) {
            response.setStatus(HttpServletResponse.SC_UNAUTHORIZED); // 401 未授权
            response.getWriter().write("Unauthorized access!");
            return false; // 阻止请求继续
        }
        return true; // 继续执行后续拦截器和处理器
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("请求处理完成，视图渲染前: " + request.getRequestURI());
        // 可以在这里对返回的ModelAndView做一些修改
        if (modelAndView != null) {
            modelAndView.addObject("appName", "MyWebApp");
        }
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        long startTime = (Long) request.getAttribute("startTime");
        long endTime = System.currentTimeMillis();
        long executeTime = endTime - startTime;
        System.out.println("请求处理结束，总耗时: " + executeTime + "ms for " + request.getRequestURI());
        if (ex != null) {
            System.err.println("请求处理中发生异常: " + ex.getMessage());
        }
    }
}

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 MyRequestInterceptor())
                .addPathPatterns("/**") // 拦截所有路径
                .excludePathPatterns("/public/**"); // 排除某些路径
    }
}

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebFilter(urlPatterns = "/*") // 拦截所有路径
public class MyBasicFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("MyBasicFilter 初始化...");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletResponse httpResponse = (HttpServletResponse) response;

        System.out.println("Filter 拦截到请求: " + httpRequest.getRequestURI());

        // 在这里可以对请求进行预处理，比如修改请求头、参数等
        // 如果不调用chain.doFilter，请求就会在这里被中断
        // 比如，一个简单的IP黑名单
        String clientIp = httpRequest.getRemoteAddr();
        if ("127.0.0.1".equals(clientIp)) { // 假设127.0.0.1是黑名单
            httpResponse.setStatus(HttpServletResponse.SC_FORBIDDEN); // 403 禁止
            httpResponse.getWriter().write("Access Forbidden for your IP!");
            return; // 阻止请求继续
        }

        chain.doFilter(request, response); // 将请求传递给下一个过滤器或目标资源

        // 请求处理完成后，可以在这里对响应进行后处理
        System.out.println("Filter 处理完成响应: " + httpRequest.getRequestURI());
        // 比如，添加一个自定义响应头
        httpResponse.setHeader("X-Processed-By", "MyBasicFilter");
    }

    @Override
    public void destroy() {
        System.out.println("MyBasicFilter 销毁...");
    }
}

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class MyControllerAspect {

    // 定义一个切入点，匹配所有在com.example.controller包下的方法
    @Pointcut("execution(* com.example.controller.*.*(..))")
    public void controllerMethods() {}

    @Around("controllerMethods()")
    public Object logAndMonitor(ProceedingJoinPoint joinPoint) throws Throwable {
        long startTime = System.currentTimeMillis();
        String methodName = joinPoint.getSignature().getName();
        System.out.println("AOP: 方法 " + methodName + " 开始执行...");

        Object result = null;
        try {
            result = joinPoint.proceed(); // 执行目标方法
            System.out.println("AOP: 方法 " + methodName + " 执行成功。");
        } catch (Throwable e) {
            System.err.println("AOP: 方法 " + methodName + " 执行异常: " + e.getMessage());
            throw e; // 重新抛出异常
        } finally {
            long endTime = System.currentTimeMillis();
            System.out.println("AOP: 方法 " + methodName + " 执行耗时: " + (endTime - startTime) + "ms");
        }
        return result;
    }
}