SpringMVC打印请求参数和响应数据最优方案
作者:brucelwl
项目中经常需要打印http请求的参数和响应数据, 但会出现如下问题:
- 打印Request Body参数: 请求
content-type是application/josn格式,如果直接从HttpServletRequest中获取输入流, 解析请求数据, 会导致SpringMVC后续的请求异常, 读取输入流异常. - 打印响应数据: 如果直接从
HttpServletResponse中获取输出流, 解析响应数据, 会导致Web服务器(Tomcat)后续响应请求异常.
本文讲解如何在SpringBoot中使用最优方案实现该功能.
常见方案(非最优方案)
常见方案就是通过实现javax.servlet.Filter对HttpServletRequest和HttpServletResponse进行包装, 将输入/输出流复制一份, 转成字符串打印, 并且不影响后续处理.而且SpringMVC已经为我们提供了相应的包装类实现
org.springframework.web.util.ContentCachingRequestWrapperorg.springframework.web.util.ContentCachingResponseWrapper
但在使用ContentCachingResponseWrapper时, 一定要记住必须调用ContentCachingResponseWrapper#copyBodyToResponse()将响应数据写回HttpServletResponse的ServletOutputStream,这样才能成功返回数据到客户端。
注意: 这个并不是最优方案,并且存在诸多缺点
示例代码如下:
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
if (isStream(request)) {
filterChain.doFilter(request, response);
return;
}
boolean isFirstRequest = !isAsyncDispatch(request);
HttpServletRequest requestToUse = request;
ContentCachingResponseWrapper responseToUse = new ContentCachingResponseWrapper(response);
if (isFirstRequest && !(request instanceof ContentCachingRequestWrapper)) {
requestToUse = new ContentCachingRequestWrapper(request);
}
try {
filterChain.doFilter(requestToUse, responseToUse);
} finally {
accessLog(requestToUse, responseToUse);
responseToUse.copyBodyToResponse();
}
}
private boolean isStream(HttpServletRequest request) {
return MediaType.TEXT_EVENT_STREAM_VALUE.equalsIgnoreCase(request.getHeader(HttpHeaders.ACCEPT))
|| MediaType.TEXT_EVENT_STREAM_VALUE.equalsIgnoreCase(request.getHeader(HttpHeaders.CONTENT_TYPE));
}这个方案存在如下几个缺点:
- 使用包装类包装
HttpServletRequest和HttpServletResponse会导致输入流和输出流被多拷贝一次 - 并不是所有的请求类型都适合对
HttpServletResponse包装, 即使用Spring提供的ContentCachingResponseWrapper也无法实现, 例如SpringMVC所支持的SSE(org.springframework.web.servlet.mvc.method.annotation.SseEmitter)请求,会导致无法向客户端相应数据. 需要对text/event-stream请求做特殊处理.
SpringWeb 5.1.14版本中ShallowEtagHeaderFilter#disableContentCaching方法的注释中已经说明
/**
* This method can be used to disable the content caching response wrapper
* of the ShallowEtagHeaderFilter. This can be done before the start of HTTP
* streaming for example where the response will be written to asynchronously
* and not in the context of a Servlet container thread.
* @since 4.2
*/
public static void disableContentCaching(ServletRequest request) {
Assert.notNull(request, "ServletRequest must not be null");
request.setAttribute(STREAMING_ATTRIBUTE, true);
}不方便获取Request Body对应的实体类类型, 不方便知道响应请求的实体类类型
最优方案
实际上SpringMVC提供了如下两个接口,用于在解析Request Body后和响应请求前回调
org.springframework.web.servlet.mvc.method.annotation.RequestBodyAdviceRequestBodyAdvice用于解析Request Body后回调, 可以实现该接口得到解析后的Body实体类,RequestBodyAdviceAdapter适配了RequestBodyAdviceorg.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdviceResponseBodyAdvice用于在向http请求响应数据之前回调, 可以实现该接口得到响应的实体类
为了能够一块打印请求和响应数据, 必须在请求时记录Request Body对象, 这里就考虑使用HttpServletRequest的setAttribute记录,但是RequestBodyAdvice中无法拿到HttpServletRequest,因此需要在请求时通过ThreadLocal绑定. 见示例ThreadBindRequestContainer
@Slf4j
@ControllerAdvice
public class RequestResponseBodyAdvice extends RequestBodyAdviceAdapter implements ResponseBodyAdvice<Object> {
@Override
public boolean supports(MethodParameter methodParameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
return true;
}
@Override
public Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
HttpServletRequest request = ThreadBindRequestContainer.getServletRequest();
Method method = parameter.getMethod();
String declaringClass = method.getDeclaringClass().getSimpleName();
String handlerMethod = method.toString().substring(method.toString().indexOf(declaringClass));
request.setAttribute("handlerMethod", handlerMethod);
request.setAttribute("req_body", body);
return body;
}
@Override
public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
return true;
}
@Override
public Object beforeBodyWrite(Object body, MethodParameter returnType,
MediaType selectedContentType,
Class<? extends HttpMessageConverter<?>> selectedConverterType,
ServerHttpRequest request,
ServerHttpResponse response) {
HttpServletRequest servletRequest = ((ServletServerHttpRequest) request).getServletRequest();
servletRequest.setAttribute("resp_body", body);
return body;
}
}public class ThreadBindRequestContainer {
private static final ThreadLocal<HttpServletRequest> threadLocal = new ThreadLocal<>();
public static void bind(HttpServletRequest request) {
threadLocal.set(request);
}
public static void remove() {
threadLocal.remove();
}
public static HttpServletRequest getServletRequest() {
return threadLocal.get();
}
}@Slf4j
public class RequestResponseBodyInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
ThreadBindRequestContainer.bind(request);
log.info("请求线程" + Thread.currentThread().getName());
return HandlerInterceptor.super.preHandle(request, response, handler);
}
@Override
public void afterCompletion(HttpServletRequest req, HttpServletResponse response, Object handler, Exception ex) throws Exception {
ThreadBindRequestContainer.remove();
String requestURI = req.getRequestURI();
Object req_body = req.getAttribute("req_body");
Object resp_body = req.getAttribute("resp_body");
Object handlerMethod = req.getAttribute("handlerMethod");
log.info("请求url:{},处理方法:{}, 参数:{}, 响应参数:{}", requestURI, handlerMethod, req_body, resp_body);
log.info("退出线程" + Thread.currentThread().getName() + "\n");
}
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