Filter过滤器,Intercepter拦截器,RequestBodyAdvice,ResponseBodyAdvice,AOP使用总结

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最近看项目代码,发现里面用到了过滤器,拦截器等来对请求参数和返回参数做校验,加密,解密,种类太多,容易混淆,这里做一下记录.

1.Filter过滤器

Filter是Servlet规范中规定的，只能用于WEB中, 在Servlet前后起作用
它可以对几乎所有请求进行过滤，但是缺点是一个过滤器实例只能在容器初始化时调用一次
使用场景: 修改字符编码; 对入参进行校验, 校验不通过返回错误信息.
原理: 基于函数回调
使用方式:

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;@WebFilter(urlPatterns = "/home/*")
public class Filter1 implements Filter {@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {HttpServletRequest request = (HttpServletRequest)servletRequest;//GetHttpServletRequestWrapper 是自定义的,可以不用管,继承自类 HttpServletRequestWrapper, 重写了 public Map<String, String[]> getParameterMap() 方法//request = new GetHttpServletRequestWrapper(request);if (request.getParameterMap().size() == 0) {servletResponse.setContentType("text/json");servletResponse.setCharacterEncoding("UTF-8");ServletOutputStream servletOutputStream = null;servletOutputStream = servletResponse.getOutputStream();servletOutputStream.write("没有入参".getBytes("UTF-8"));servletOutputStream.flush();servletOutputStream.close();return;}//继续执行后面的过滤器,如果没有这一行,那么这个请求就被拦截了filterChain.doFilter(servletRequest, servletResponse);}
}

另外需要在启动类上添加 @ServletComponentScan 注解(会自动注册@WebServlet、@WebFilter、@WebListener)

2.Interceptor拦截器

拦截器是Spring容器内的，是Spring框架支持的,可以使用Spring内的任何资源、对象
可以深入到方法的调用前后、异常抛出前后等深层次的程度做处理
缺点是只能对 Controller 请求进行拦截，对其他的一些比如直接访问静态资源的请求则没办法进行拦截处理
原理: 基于Java的反射机制，属于面向切面编程（AOP）的一种运用
使用场景: 对入参进行校验
使用方式:

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {@Overridepublic void addInterceptors(InterceptorRegistry registry) {// 注册拦截器registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**");}
}public class MyInterceptor extends HandlerInterceptorAdapter {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {String childCode = request.getParameter("child_code");if(StringUtils.isBlank(username)) {// 拦截请求return false;}return true;}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) {}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) {}
}

3.RequestBodyAdvice

配合 @ControllerAdvice 和 @RequestBody 注解使用, 可以拦截所有的请求. 如果不使用 @RequestBody 修饰入参对象, 不会拦截
原理: AOP
使用场景: 参数的过滤,字符的编码,第三方的解密
使用方式:

@ControllerAdvice(basePackages = "com.example.controller")
public class DecodeRequestBodyAdvice implements RequestBodyAdvice {@Overridepublic boolean supports(MethodParameter methodParameter, Type type, Class<? extends HttpMessageConverter<?>> aClass) {// 返回false会拦截return true;}@Overridepublic HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter methodParameter, Type type, Class<? extends HttpMessageConverter<?>> aClass) throws IOException {try {return new MyHttpInputMessage(inputMessage);} catch (Exception e) {e.printStackTrace}}@Overridepublic Object afterBodyRead(Object o, HttpInputMessage httpInputMessage, MethodParameter methodParameter, Type type, Class<? extends HttpMessageConverter<?>> aClass) {return o;}@Overridepublic Object handleEmptyBody(Object o, HttpInputMessage httpInputMessage, MethodParameter methodParameter, Type type, Class<? extends HttpMessageConverter<?>> aClass) {return o;}class MyHttpInputMessage implements HttpInputMessage {private HttpHeaders headers;private InputStream body;public MyHttpInputMessage(HttpInputMessage inputMessage) throws Exception {this.headers = inputMessage.getHeaders();try {String bodyStr = StringUtils.defaultString(IOUtils.toString(inputMessage.getBody(), Util.CHARSET_UTF8));String bodyStrDe = AesUtil.decrypt(bodyStr);this.body = IOUtils.toInputStream(bodyStrDe, Util.CHARSET_UTF8);} catch (Exception e) {e.printStackTrace;}}@Overridepublic InputStream getBody() throws IOException {return body;}@Overridepublic HttpHeaders getHeaders() {return headers;}}	
}

4.ResponseBodyAdvice

拦截Controller方法默认返回参数，统一处理返回值/响应体
使用场景: 对控制层的返回结果进行加密
原理: AOP
使用方式:

@ControllerAdvice(basePackages = "com.example.controller")
public class EncodeResponseBodyAdvice implements ResponseBodyAdvice {@Overridepublic boolean supports(MethodParameter methodParameter, Class aClass) {return true;}@Overridepublic Object beforeBodyWrite(Object o, MethodParameter methodParameter, MediaType mediaType, Class aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {try {String result = JSON.toJSONString(o, SerializerFeature.DisableCircularReferenceDetect);Map<String, String> map = new HashMap<>();map.put("result", AesUtil.encrypt(result));// 这边不直接返回加密字符串,是因为控制层使用了@ResponseBody注解,直接返回字符串会在前后各多出一个双引号return map;} catch (Exception e) {e.printStackTrace;}return o;}
}

5.AOP使用

面向切面编程，在程序开发中主要用来解决一些系统层面上的问题，比如日志，事务，权限等
使用场景: 统一记录控制层请求日志以及返回结果
使用方式:

import com.alibaba.fastjson.JSON;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.InputStreamSource;
import org.springframework.stereotype.Component;
import org.springframework.web.multipart.MultipartFile;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;@Component
@Aspect
public class ServiceAspect {private final HttpServletRequest request;private Logger sevicelog = LoggerFactory.getLogger("serviceLog");@Autowiredpublic ServiceAspect(HttpServletRequest request) {this.request = request;}@Around("execution(* com.example.controller.*.*(..))")public Object serviceBefore(ProceedingJoinPoint pjp) throws Throwable {Map<String, Object> logMap1 = new HashMap<>();Signature signature = pjp.getSignature();MethodSignature methodSignature = (MethodSignature) signature;//2.最关键的一步:通过这获取到方法的所有参数名称的字符串数组String[] parameterNames = methodSignature.getParameterNames();int i = 0;for (Object arg : pjp.getArgs()) {String argValue="";if(!(arg instanceof HttpServletRequest ||arg instanceof HttpServletResponse||arg instanceof InputStreamSource ||arg instanceof MultipartFile)){try {if(arg instanceof List){List b=(List) arg;if(!b.isEmpty()){if(b.get(0) instanceof MultipartFile){continue;}}}argValue= JSON.toJSONString(arg);}catch (Exception e){e.printStackTrace();}}logMap1.put(parameterNames[i++], argValue);}Map<String, Object> logMap = new HashMap<>();logMap.put("msg", logMap1);Object result = pjp.proceed();logMap.put("result", result);logMap.put("method", signature.getName());logMap.put("sub_project", "interface");logMap.put("ip", IpUtil.getIpAddr(request));SimpleDateFormat dateformat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String date = dateformat.format(new Date());logMap.put("visit_date", date);logMap.put("project_name", "SpringBoot");sevicelog.info(JSON.toJSONString(logMap));return result;}
}