SpringBoot记录HTTP请求日志
1、需求解读
需求：
框架需要记录每一个HTTP请求的信息，包括请求路径、请求参数、响应状态、返回参数、请求耗时等信息。
需求解读：
Springboot框架提供了多种方式来拦截HTTP请求和响应，只要能够获取到对应的request和response，就可以通过相应的API来获取所需要的信息。
需要注意的是，请求参数可以分为两部分，一部分是GET请求时，请求参数通过URL拼接的方式传到后端，还有一部分是通过POST请求提交Json格式的参数，这种参数会放在request body中传到后端，通过request.getParameterMap是无法获取到的。
2、Spring Boot Actuator
2.1、介绍和使用
Spring Boot Actuator 的关键特性是在应用程序里提供众多 Web 接口，通过它们了解应用程序运行时的内部状况，且能监控和度量Spring Boot 应用程序。
要使用Spring Boot Actuator，首先需要引入依赖包
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> 其次需要开启端口访问权限
management.endpoints.web.exposure.include=httptrace
Spring Boot 应用启动时可以看到控制台的信息如下，代表开启了该端口的访问
image-20180829094800774
浏览器访问/acutator/httptrace就能看到HTTP的请求情况
image-20180829100827244
2.2、默认的HttpTraceRepository
Spring Boot Actuator 默认会把最近100次的HTTP请求记录到内存中，对应的实现类是InMemoryHttpTraceRepository
public class InMemoryHttpTraceRepository implements HttpTraceRepository { private int capacity = 100; private boolean reverse = true; private final List<HttpTrace> traces = new LinkedList<>(); /** * Flag to say that the repository lists traces in reverse order. * @param reverse flag value (default true) */ public void setReverse(boolean reverse) { synchronized (this.traces) { this.reverse = reverse; } } /** * Set the capacity of the in-memory repository. * @param capacity the capacity */ public void setCapacity(int capacity) { synchronized (this.traces) { this.capacity = capacity; } } @Override public List<HttpTrace> findAll() { synchronized (this.traces) { return Collections.unmodifiableList(new ArrayList<>(this.traces)); } } @Override public void add(HttpTrace trace) { synchronized (this.traces) { while (this.traces.size() >= this.capacity) { this.traces.remove(this.reverse ? this.capacity - 1 : 0); } if (this.reverse) { this.traces.add(0, trace); } else { this.traces.add(trace); } } } } 这里add方法使用了synchronized，默认只存储最近到100条，如果并发量大的话，性能会有所影响
2.3、自定义HttpTraceRepository
我们可以自己实现HttpTraceRepository这个接口，重写add方法并记录trace日志
@Slf4j public class RemoteHttpTraceRepository implements HttpTraceRepository { @Override public List<HttpTrace> findAll() { return Collections.emptyList(); } @Override public void add(HttpTrace trace) { String path = trace.getRequest().getUri().getPath(); String queryPara = trace.getRequest().getUri().getQuery(); String queryParaRaw = trace.getRequest().getUri().getRawQuery(); String method = trace.getRequest().getMethod(); long timeTaken = trace.getTimeTaken(); String time = trace.getTimestamp().toString(); log.info("path: {}, queryPara: {}, queryParaRaw: {}, timeTaken: {}, time: {}, method: {}", path, queryPara, queryParaRaw, timeTaken, time, method); } } 将该实现类注册到Spring的容器中
@Configuration @ConditionalOnWebApplication @ConditionalOnProperty(prefix = "management.trace.http", name = "enabled", matchIfMissing = true) @EnableConfigurationProperties(HttpTraceProperties.class) @AutoConfigureBefore(HttpTraceAutoConfiguration.class) public class TraceConfig { @Bean @ConditionalOnMissingBean(HttpTraceRepository.class) public RemoteHttpTraceRepository traceRepository() { return new RemoteHttpTraceRepository(); } } 2.4、缺点
目前这种实现可以记录到请求路径、请求耗时、响应状态、请求Header、响应Header等信息，没有办法记录请求参数和响应参数。有人在github上提了个issue，作者回复说这样的设计是为了兼容Spring MVC和WebFlux两种模式，具体可以参考：https://github.com/spring-projects/spring-boot/issues/12953#issuecomment-383830749
3、Spring Boot Filter
3.1、HttpTraceFilter
既然httptrace无法满足现有的需求，我们可以顺着InMemoryHttpTraceRepository这个默认实现往上找，看看谁调用了这个实现类。结果可以发现是被HttpTraceFilter这个拦截器（servlet模式下）进行了调用。
public class HttpTraceFilter extends OncePerRequestFilter implements Ordered { // Not LOWEST_PRECEDENCE, but near the end, so it has a good chance of catching all // enriched headers, but users can add stuff after this if they want to private int order = Ordered.LOWEST_PRECEDENCE - 10; private final HttpTraceRepository repository; private final HttpExchangeTracer tracer; /** * Create a new {@link HttpTraceFilter} instance. * @param repository the trace repository * @param tracer used to trace exchanges */ public HttpTraceFilter(HttpTraceRepository repository, HttpExchangeTracer tracer) { this.repository = repository; this.tracer = tracer; } @Override public int getOrder() { return this.order; } public void setOrder(int order) { this.order = order; } @Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { if (!isRequestValid(request)) { filterChain.doFilter(request, response); return; } TraceableHttpServletRequest traceableRequest = new TraceableHttpServletRequest( request); HttpTrace trace = this.tracer.receivedRequest(traceableRequest); int status = HttpStatus.INTERNAL_SERVER_ERROR.value(); try { filterChain.doFilter(request, response); status = response.getStatus(); } finally { TraceableHttpServletResponse traceableResponse = new TraceableHttpServletResponse( (status != response.getStatus()) ? new CustomStatusResponseWrapper(response, status) : response); this.tracer.sendingResponse(trace, traceableResponse, request::getUserPrincipal, () -> getSessionId(request)); this.repository.add(trace); } } ...省略部分代码 } tracer中会记录HTTP的请求耗时
3.2、自定义HttpTraceFilter获取请求参数
在HttpTraceFilter继承了OncePerRequestFilter，我们可以仿照这个过滤器，定义自己的过滤器去继承OncePerRequestFilter，在doFilterInternal这个方法中获取到HttpServletRequest，HttpServletResponse，这样就可以获取到对应的请求参数和返回参数了。
GET请求时的参数可以通过以下方式进行获取：
String parameterMap = request.getParameterMap() POST请求会将参数放入request body中，用以下方式进行获取：
String requestBody = IOUtils.toString(request.getInputStream(), Charsets.UTF_8); 很不幸，代码运行会抛出异常
image-20180829111619987
原因是：body里字符的传输是通过HttpServletRequest中的字节流getInputStream()获得的；而这个字节流在读取了一次之后就不复存在了。
解决方法：利用ContentCachingRequestWrapper对HttpServletRequest的请求包一层，该类会将inputstream中的copy一份到自己的字节数组中，这样就不会报错了。读取完body后，需要调用
wrappedResponse.copyBodyToResponse(); 将请求还原。
3.3、完整的自定义HttpTraceFilter
@Slf4j public class HttpTraceLogFilter extends OncePerRequestFilter implements Ordered { private static final String NEED_TRACE_PATH_PREFIX = "/api"; private static final String IGNORE_CONTENT_TYPE = "multipart/form-data"; private final MeterRegistry registry; public HttpTraceLogFilter(MeterRegistry registry) { this.registry = registry; } @Override public int getOrder() { return Ordered.LOWEST_PRECEDENCE - 10; } @Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { if (!isRequestValid(request)) { filterChain.doFilter(request, response); return; } if (!(request instanceof ContentCachingRequestWrapper)) { request = new ContentCachingRequestWrapper(request); } if (!(response instanceof ContentCachingResponseWrapper)) { response = new ContentCachingResponseWrapper(response); } int status = HttpStatus.INTERNAL_SERVER_ERROR.value(); long startTime = System.currentTimeMillis(); try { filterChain.doFilter(request, response); status = response.getStatus(); } finally { String path = request.getRequestURI(); if (path.startsWith(NEED_TRACE_PATH_PREFIX) && !Objects.equals(IGNORE_CONTENT_TYPE, request.getContentType())) { String requestBody = IOUtils.toString(request.getInputStream(), Charsets.UTF_8); log.info(requestBody); //1. 记录日志 HttpTraceLog traceLog = new HttpTraceLog(); traceLog.setPath(path); traceLog.setMethod(request.getMethod()); long latency = System.currentTimeMillis() - startTime; traceLog.setTimeTaken(latency); traceLog.setTime(LocalDateTime.now().