【拦截器、过滤器、springAop】那些不为人知的隐秘

首先说到这几个词的时候，大家肯定都很熟悉了，甚至觉得这几个的区别刚刚毕业都能回答了，但是我想大家在实际应用过程中是真得会真正的使用吗？换言之，什么时候用过滤器什么时候使用拦截器，什么时候使用springAop呢？很多时候不觉得这些都可以实现吗？比如日志的打印，我觉得都可以实现，那在设计架构的时候应该如何去考量呢？废话不多说，接下来我会用实际的案例来展示，大家看看是否真的如你们心里所想的呢？或者有么有更好的方案欢迎评论区留言！！！
首先说一些基础的它们之间的执行顺序

作用域大小不一样。

过滤器Filter是在请求进入容器后，但在进入servlet之前进行预处理，请求结束是在servlet处理完以后。

拦截器 Interceptor 是在请求进入servlet后，在进入Controller之前进行预处理的，Controller
中渲染了对应的视图之后请求结束。

过滤器/拦截器与aop获取的信息不一样。过滤器/拦截器获取的是请求级别的信息，如url、传参、header、返回值等信息。

aop不能获取请求的参数等信息，和返回结果。aop能获取到调用的类，方法及方法参数。以及方法的返回值。

如果想通过方法进行拦截/过滤等处理，需要使用aop。如果想通过请求判断，需要使用过滤器。但是aop获取的是方法级别的信息，类、方法、方法的传参等等。

背景

现在有个业务场景就是通过前后端密文加解密实现参数传递，前端都是通过密文传递的并且是通过post请求方式的，后端之间使用对象来映射的，我们想通过上面的方式实现和业务解耦

方案讨论

过滤器可以获取到所有的request和response，是根据url匹配的
拦截器获取不到request和response参数，但是可以获取到所有的方法、类、参数等信息，也是根据url匹配的
springAop拦截器获取不到request和response参数，但是可以获取到所有的方法、类、参数等信息，是根据切点的也就是方法来匹配的
还有一点区别那就是如果是get请求可以很轻松获取但是如果是post那就要注意了，因为body的数据读取是通过流形式读取的，如果你在过滤器中读取到了，那么在controller中mvc参数映射的时候就会报错，因为拿不到body的值，因为流读取只会读取到一次，你在过滤器中读取到了，那么mvc参数映射的时候就无法读取不到，还有就是springAop或者是拦截器最早发生的时机也需要发生在mvc参数映射之后的，否则怎么能拿到参数信息呢，这点就是提下
那么既然这么说了，肯定有办法解决嘛，那就是你获取到了body的数据，就需要重新包装下然后set回去

springAop

import lombok.Data;/*** 责任链接口** @author fangh* @date 2023-02-09 11:22*/
@Data
public abstract class ProcessingObject<T> {private ProcessingObject<T> successor;public T handle(T input, String apiName) {T t = handleWork(input, apiName);if (successor != null) {return successor.handle(t, apiName);}return t;}/*** 子类的具体处理方法** @param input   待处理的参数* @param apiName 接口名* @return 处理后的参数*/abstract protected T handleWork(T input, String apiName);
}

import com.fh.inter.mgmt.service.GetVehicleInfoService;
import com.fh.inter.mgmt.service.impl.GenerateReturnSign;
import com.fh.standard.config.SystemCommonConfig;
import com.fh.standard.constant.MdcConstant;
import com.fh.standard.dto.BaseDTO;
import com.fh.standard.enums.ApiEnum;
import com.fh.standard.enums.ApiResultEnum;
import com.fh.standard.exception.BusinessException;
import com.fh.standard.vo.BaseVO;
import com.alibaba.fastjson.JSON;
import com.google.common.collect.Maps;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.slf4j.MDC;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;import java.lang.reflect.Method;
import java.util.Map;/*** <p>AOP 类，包含请求/响应日志打印、签名验证、车辆信息校验等</p>* <p>需要留意下 AOP 的执行顺序：</p>** @author fangh* @date 2023-02-09 11:22*/
@Aspect
@Component
@Order(0)
@Slf4j
@RequiredArgsConstructor
public class RequestAop {/*** 请求参数日志打印*/private final RequestLogPrint p1;/*** 签名处理*/private final ValidateSign p2;/*** 校验请求参数*/private final CheckRequestParam p3;private final ThreadLocal<Map<String, String>> threadLocal = new ThreadLocal<>();/*** 返回报文签名生成*/private final GenerateReturnSign generateReturnSign;private final GetVehicleInfoService getVehicleInfoService;private final SystemCommonConfig config;/*** Key：apiName 接口方法名 Value：apiDesc 接口方法名中文描述*/private final static Map<String, String> METHOD_MAP = Maps.newHashMapWithExpectedSize(ApiEnum.values().length);static {METHOD_MAP.put(ApiEnum.RDS_REGISTER.getMethodName(), ApiEnum.RDS_REGISTER.getApiName());METHOD_MAP.put(ApiEnum.RDS_CHECK.getMethodName(), ApiEnum.RDS_CHECK.getApiName());METHOD_MAP.put(ApiEnum.RDS_TASK_INFO.getMethodName(), ApiEnum.RDS_TASK_INFO.getApiName());METHOD_MAP.put(ApiEnum.RDS_DOWNlOAD_STATE_REPORT.getMethodName(), ApiEnum.RDS_DOWNlOAD_STATE_REPORT.getApiName());METHOD_MAP.put(ApiEnum.RDS_REPORT_LOG.getMethodName(), ApiEnum.RDS_REPORT_LOG.getApiName());}/*** 对 Controller 做切点*/@Pointcut("execution(* com.adups.inter.mgmt.controller..*.*(..))")public void pointcut() {}@Before("pointcut()")public void doBefore(JoinPoint joinPoint) {// 接口形参列表Object[] args = joinPoint.getArgs();for (Object arg : args) {if (arg instanceof BaseDTO) {BaseDTO baseDTO = (BaseDTO) arg;String methodName = currentMethod(joinPoint);// 请求接口名称String apiName = METHOD_MAP.get(methodName);// 请求参数日志打印 -> 非注册接口的车辆信息获取 -> 验签 -> ecuDids 解析 -> ecuPartNum 解析 -> exts 解析// 设置调用顺序p1.setSuccessor(p2);p2.setSuccessor(p3);// 开始按顺序链式处理p1.handle(baseDTO, apiName);break;}}}@AfterReturning(pointcut = "pointcut()", returning = "returnValue")public void doAfterReturn(JoinPoint joinPoint, Object returnValue) {Map<String, String> signMap = threadLocal.get();String methodName = currentMethod(joinPoint);String apiName = METHOD_MAP.get(methodName);if (apiName == null) {log.error("请求 Url 不存在");throw new BusinessException(ApiResultEnum.PARAM_VERIFICATION_FAIL, "请求 Url 不存在");}if (returnValue == null) {log.error("{} 接口返回值为 null，请检查代码", apiName);throw new BusinessException(ApiResultEnum.UNKNOWN_ERROR);}BaseVO baseVO = (BaseVO) returnValue;String sign = generateReturnSign.initReturnSign(baseVO, signMap.get(MdcConstant.SIGN_KEY), null);baseVO.setSign(sign);// 正常响应参数日志打印log.info(apiName + "响应：" + JSON.toJSONString(baseVO));}private String currentMethod(JoinPoint joinPoint) {String methodName = joinPoint.getSignature().getName();Method[] methods = joinPoint.getTarget().getClass().getMethods();Method resultMethod = null;for (Method method : methods) {if (method.getName().equals(methodName)) {resultMethod = method;break;}}return resultMethod == null ? "" : resultMethod.getName();}}

/*** 请求参数打印** @author Xinling Jing* @date 2021-05-17 11:02*/
@Component
@Slf4j
@Setter
public class RequestLogPrint extends ProcessingObject<BaseDTO> {@Overrideprotected BaseDTO handleWork(BaseDTO input, String apiName) {log(JSON.toJSONString(input), apiName);return input;}private void log(String json, String apiName) {log.info(apiName + "请求：" + json);}
}

过滤器

package com.adups.inter.mgmt.filter;import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.fh.inter.mgmt.dto.RegisterDTO;
import com.fh.inter.mgmt.service.GetVehicleInfoService;
import com.fh.standard.config.SystemCommonConfig;
import com.fh.standard.constant.MdcConstant;
import com.fh.standard.entity.VehicleInfoDO;
import com.fh.standard.enums.ApiEnum;
import com.fh.standard.util.AesUtils;
import lombok.RequiredArgsConstructor;
import org.apache.commons.io.IOUtils;
import org.slf4j.MDC;
import org.springframework.core.annotation.Order;import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.nio.charset.StandardCharsets;/*** 报文解密过滤器** @author fangh* @date 2023-02-15 18:27*/
@Order(0)
@WebFilter(urlPatterns = "/idiagnosis/*")
@RequiredArgsConstructor
public class DecreptFilter implements Filter {private final SystemCommonConfig config;private final GetVehicleInfoService getVehicleInfoService;@Overridepublic void init(FilterConfig filterConfig) throws ServletException {Filter.super.init(filterConfig);}@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse response, FilterChain chain) throws IOException, ServletException {if (!config.isEncrypt()) {chain.doFilter(servletRequest, response);return;}// 获取请求uriString uri = ((HttpServletRequest) servletRequest).getRequestURI();// 截取注册映射值String apiName = StrUtil.subAfter(uri, StrUtil.SLASH, true);RequestWrapper requestWrapper = new RequestWrapper((HttpServletRequest) servletRequest);ResponseWrapper responseWrapper = new ResponseWrapper((HttpServletResponse) response);//获取post的值String bodyMessage = IOUtils.toString(requestWrapper.getBody(), "UTF-8");String decodeBodyMessage;if (ApiEnum.RDS_REGISTER.getMethodName().equals(apiName)) {// 解密后的报文decodeBodyMessage = config.isEncrypt() ? AesUtils.aesDecodeStr(bodyMessage, config.getKey()) : bodyMessage;// 解析jsonRegisterDTO registerDTO = JSONUtil.toBean(decodeBodyMessage, RegisterDTO.class);// 获取车辆信息VehicleInfoDO vehicleInfoDO = getVehicleInfoService.getVehicleInfoByVin(registerDTO.getVin());registerDTO.setVehicle(vehicleInfoDO);// 覆写request数据requestWrapper.setBody(JSONUtil.toJsonStr(registerDTO).getBytes(StandardCharsets.UTF_8));MDC.put(MdcConstant.REGISTER_BODY_MESSAGE, decodeBodyMessage);} else {// 截取到deviceId值String deviceId = StrUtil.subAfter(uri, StrUtil.SLASH, true);// 根据deviceId获取车辆信息VehicleInfoDO vehicleInfoDO = getVehicleInfoService.getVehicleInfoByDeviceId(deviceId);// 报文解密decodeBodyMessage = config.isEncrypt() ? AesUtils.aesDecodeStr(bodyMessage, vehicleInfoDO.getSecret()) : bodyMessage;// 车辆的secretMDC.put(MdcConstant.ENCRYPT_KEY, vehicleInfoDO.getSecret());// 解密后的报文MDC.put(MdcConstant.BODY_MESSAGE, decodeBodyMessage);// 车辆信息MDC.put(MdcConstant.VEHICLE_INFO, JSONUtil.toJsonStr(vehicleInfoDO));}chain.doFilter(requestWrapper, responseWrapper);// 获取原响应报文byte[] content = responseWrapper.getContent();// 解析responseString responseData = IOUtils.toString(content, "UTF-8");// 加密响应报文String result;if (ApiEnum.RDS_REGISTER.getMethodName().equals(apiName)) {result = AesUtils.aesEncryptStr(responseData, config.getKey());} else {// 非注册请求 加密key为车的密钥result = AesUtils.aesEncryptStr(responseData, MDC.get(MdcConstant.ENCRYPT_KEY));}// 覆写responsecontent = result.getBytes();// 注意 此处是servletResponse 不是responseWrapper,写responseWrapper的话 依旧响应不了ServletOutputStream outputStream = response.getOutputStream();outputStream.write(content);outputStream.flush();outputStream.close();MDC.clear();log.debug("当前线程局部变量已全部清除");}@Overridepublic void destroy() {Filter.super.destroy();}
}

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;/*** RequestWrapper** @author fangh* @date 2023-02-16 17:46*/
public class RequestWrapper extends HttpServletRequestWrapper {private byte[] body;public RequestWrapper(HttpServletRequest request) throws IOException {super(request);body = this.toByteArray(request.getInputStream());}private byte[] toByteArray(ServletInputStream inputStream) throws IOException {ByteArrayOutputStream out = new ByteArrayOutputStream();byte[] buffer = new byte[1024 * 4];int n;while ((n = inputStream.read(buffer)) != -1) {out.write(buffer, 0, n);}return out.toByteArray();}@Overridepublic BufferedReader getReader() {return new BufferedReader(new InputStreamReader(getInputStream()));}@Overridepublic ServletInputStream getInputStream() {final ByteArrayInputStream bais = new ByteArrayInputStream(body);return new ServletInputStream() {@Overridepublic boolean isFinished() {return false;}@Overridepublic boolean isReady() {return false;}@Overridepublic void setReadListener(ReadListener readListener) {}@Overridepublic int read() {return bais.read();}};}public byte[] getBody() {return body;}public void setBody(byte[] data) {body = data;}
}

import javax.servlet.ServletOutputStream;
import javax.servlet.WriteListener;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.nio.charset.StandardCharsets;/*** ResponseWrapper** @authorfangh* @date 2023-02-16 17:46*/
public class ResponseWrapper extends HttpServletResponseWrapper {private final ByteArrayOutputStream byteArrayOutputStream;private final ServletOutputStream servletOutputStream;private final PrintWriter writer;public ResponseWrapper(HttpServletResponse response) {super(response);byteArrayOutputStream = new ByteArrayOutputStream();servletOutputStream = new WapperedOutputStream(byteArrayOutputStream);writer = new PrintWriter(new OutputStreamWriter(byteArrayOutputStream, StandardCharsets.UTF_8));}@Overridepublic ServletOutputStream getOutputStream() {return servletOutputStream;}@Overridepublic PrintWriter getWriter() {return writer;}@Overridepublic void flushBuffer() {if (servletOutputStream != null) {try {servletOutputStream.flush();} catch (IOException e) {e.printStackTrace();}}if (writer != null) {writer.flush();}}@Overridepublic void reset() {byteArrayOutputStream.reset();}public String getResponseData(String charset) throws IOException {flushBuffer();return byteArrayOutputStream.toString(charset);}private static class WapperedOutputStream extends ServletOutputStream {private final ByteArrayOutputStream bos;public WapperedOutputStream(ByteArrayOutputStream stream) {bos = stream;}@Overridepublic boolean isReady() {return false;}@Overridepublic void setWriteListener(WriteListener writeListener) {}@Overridepublic void write(int b) {bos.write(b);}}public byte[] getContent() {flushBuffer();return byteArrayOutputStream.toByteArray();}
}