背景
零碎须要上报每次的申请信息，并上报数据给监控平台。
问题
获取接口返回对象
零碎接口是RestController，返回的后果都是@ResponseBody对象。上报数据时，须要解析返回后果对象，提取对象中的状态码。从response对象中获取返回后果对象，之前是在filter中通过ContentCachingResponseWrapper形式来获取：
public class AccessLogFilter extends OncePerRequestFilter implements Ordered { @Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { long biginTime = System.currentTimeMillis(); HttpServletRequest httpServletRequest = request; HttpServletResponse httpServletResponse = response; if (!(httpServletRequest instanceof ContentCachingRequestWrapper)) { httpServletRequest = new ContentCachingRequestWrapper(request); } if (!(httpServletResponse instanceof ContentCachingResponseWrapper)) { httpServletResponse = new ContentCachingResponseWrapper(response); } try { …… // 其余操作 filterChain.doFilter(httpServletRequest, httpServletResponse); String responseBody = invokeHttpByteResponseData((ContentCachingResponseWrapper) httpServletResponse); …… // 上报等其余操作 } finally { ((ContentCachingResponseWrapper) httpServletResponse).copyBodyToResponse(); AccessLogEntityHolder.remove(); } } public String invokeHttpByteResponseData(ContentCachingResponseWrapper response) { try { String charset = getResponseCharset(response); return IOUtils.toString(response.getContentAsByteArray(), charset); } catch (IOException e) { throw new RuntimeException("拜访日志解析器解析接口返回数据异样！", e); } } protected String getResponseCharset(ContentCachingResponseWrapper response) { if (response.getContentType() == null) { return StandardCharsets.UTF_8.name(); } boolean isStream = response.getContentType() .equalsIgnoreCase(MediaType.APPLICATION_OCTET_STREAM_VALUE); return isStream && StringUtils.isNotBlank(response.getCharacterEncoding()) ? response.getCharacterEncoding() : StandardCharsets.UTF_8.name(); } }当初因为放心跟引入的一个第三次插件包里的filter有抵触，改为应用Interceptor形式。而spring的Interceptor无奈像filter那样构建新的request和response。
这里的解决方案是，通过ControllerAdvice来获取存储对象，即ControllerAdvice里的beforeBodyWrite办法，在执行时，将参数里的body临时存储起来，这里的存储，采纳了ThreadLocal计划。
计划如下：
@ControllerAdvicepublic classXXXMetricInterceptor implements HandlerInterceptor, Ordered, ResponseBodyAdvice<Object> { private static final ThreadLocal<Object> resultBodyThreadLocal = new ThreadLocal(); @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) { resultBodyThreadLocal.set(body); return body; } @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { } } 然而以上有个问题，开发的Interceptor是个公共组件，容许其余我的项目扩大，也就是说，到时候配置形式是在@Configuration里配置：
@Bean@ConditionalOnMissingBean(XXXMetricInterceptor.class)public XXXMetricInterceptor getXXXMetricInterceptor() { return newXXXMetricInterceptor();}而以上计划因为@ControllerAdvice注解里蕴含了@Component，无奈做@ConditionalOnMissingBean判断，所以改为将@ControllerAdvice局部独立取出，而后在Interceptor里注入：
public class XXXMetricInterceptor implements HandlerInterceptor, Ordered { @Autowired private XXXResponseBodyStorage responseBodyStorage; }@ControllerAdvicepublic class XXXResponseBodyStorage implements Ordered, ResponseBodyAdvice<Object> { private static final ThreadLocal<Object> resultBodyThreadLocal = new ThreadLocal(); @Override public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) { return enable; } @Override public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) { resultBodyThreadLocal.set(body); return body; } public Object get() { return resultBodyThreadLocal.get(); } public void remove() { resultBodyThreadLocal.remove(); } @Override public int getOrder() { return Ordered.LOWEST_PRECEDENCE; }}注：spring容许多个ControllerAdvice对象存在，理论我的项目中曾经存在专门对后果做转换的ControllerAdvice对象。
获取环境
因为不同的环境（如test，prod），要上报数据到不同的中央，所以在初始化时，须要对环境做判断，这里能够通过初始化（@PostConstruct）办法里，取applicationContext.getEnvironment().getActiveProfiles()来判断，然而通过测试发现：
- 如果没有对
XXXMetricInterceptor做继承扩大的话（XXXMetricInterceptor放在公共包里，以jar的形式被引入），getActiveProfiles办法能取到值。 - 如果在理论我的项目中对
XXXMetricInterceptor做了继承扩大，那么@PostConstruct办法里getActiveProfiles返回的是空。
解决方案是调整初始化的工夫点，改为在spring的application可用时再初始化：
public class XXXMetricInterceptor implements ApplicationListener<ApplicationReadyEvent>, HandlerInterceptor, Ordered { @Override public void onApplicationEvent(ApplicationReadyEvent event) { String[] activeProfiles = SpringContextUtil.getApplicationContext() == null ? null : SpringContextUtil.getActiveProfile(); …… } }数据上报
刚开始数据尚博啊是放在拦截器的PostHandler办法里：
public class XXXMetricInterceptor implements ApplicationListener<ApplicationReadyEvent>, HandlerInterceptor, Ordered { @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { …… // 数据上报 }}测试发现，当接口发送异样时，并不会进入到postHandle，之后改为在afterCompletion办法里：
public class XXXMetricInterceptor implements ApplicationListener<ApplicationReadyEvent>, HandlerInterceptor, Ordered { @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { try { …… //数据上报 } catch (Exception e) { …… } finally { responseBodyStorage.remove(); } } } 如果接口产生异样，会先通过@ExceptionHandler的解决，之后进入ControllerAdvice环节，再之后进入到afterCompletion中。