作者：fredalxin
地址：https://fredal.xin/http-body-…
常常会遇到须要解决 http 申请以及响应 body 的场景。
而这里比拟大的一个问题是 servle t 的 requestBody 或 responseBody 流一旦被读取了就无奈二次读取了。
针对这个问题，spring 自身提供了解决方案，即：
- ContentCachingRequestWrapper
- ContentCachingResponseWrapper。
咱们编写一个过滤器:
public abstract class HttpBodyRecorderFilter extends OncePerRequestFilter {
private static final int DEFAULT_MAX_PAYLOAD_LENGTH = 1024 * 512;
private int maxPayloadLength = DEFAULT_MAX_PAYLOAD_LENGTH;
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {boolean isFirstRequest = !isAsyncDispatch(request);
HttpServletRequest requestToUse = request;
if (isFirstRequest && !(request instanceof ContentCachingRequestWrapper)
&& (request.getMethod().equals(HttpMethod.PUT.name())
|| request.getMethod().equals(HttpMethod.POST.name()))) {requestToUse = new ContentCachingRequestWrapper(request);
}
HttpServletResponse responseToUse = response;
if (!(response instanceof ContentCachingResponseWrapper) && (request.getMethod().equals(HttpMethod.PUT.name())
|| request.getMethod().equals(HttpMethod.POST.name()))) {responseToUse = new ContentCachingResponseWrapper(response);
}
boolean hasException = false;
try {filterChain.doFilter(requestToUse, responseToUse);
} catch (final Exception e) {
hasException = true;
throw e;
} finally {int code = hasException ? 500 : response.getStatus();
if (!isAsyncStarted(requestToUse) && (this.codeMatched(code, AdvancedHunterConfigManager.recordCode()))) {recordBody(createRequest(requestToUse), createResponse(responseToUse));
} else {writeResponseBack(responseToUse);
}
}
}
protected String createRequest(HttpServletRequest request) {
String payload = "";
ContentCachingRequestWrapper wrapper = WebUtils.getNativeRequest(request, ContentCachingRequestWrapper.class);
if (wrapper != null) {byte[] buf = wrapper.getContentAsByteArray();
payload = genPayload(payload, buf, wrapper.getCharacterEncoding());
}
return payload;
}
protected String createResponse(HttpServletResponse resp) {
String response = "";
ContentCachingResponseWrapper wrapper = WebUtils.getNativeResponse(resp, ContentCachingResponseWrapper.class);
if (wrapper != null) {byte[] buf = wrapper.getContentAsByteArray();
try {wrapper.copyBodyToResponse();
} catch (IOException e) {e.printStackTrace();
}
response = genPayload(response, buf, wrapper.getCharacterEncoding());
}
return response;
}
protected void writeResponseBack(HttpServletResponse resp) {ContentCachingResponseWrapper wrapper = WebUtils.getNativeResponse(resp, ContentCachingResponseWrapper.class);
if (wrapper != null) {
try {wrapper.copyBodyToResponse();
} catch (IOException e) {LOG.error("Fail to write response body back", e);
}
}
}
private String genPayload(String payload, byte[] buf, String characterEncoding) {if (buf.length > 0 && buf.length < getMaxPayloadLength()) {
try {payload = new String(buf, 0, buf.length, characterEncoding);
} catch (UnsupportedEncodingException ex) {payload = "[unknown]";
}
}
return payload;
}
public int getMaxPayloadLength() {return maxPayloadLength;}
private boolean codeMatched(int responseStatus, String statusCode) {if (statusCode.matches("^[0-9,]*$")) {String[] filteredCode = statusCode.split(",");
return Stream.of(filteredCode).map(Integer::parseInt).collect(Collectors.toList()).contains(responseStatus);
} else {return false;}
}
protected abstract void recordBody(String payload, String response);
protected abstract String recordCode();}这样自定义一个 filter 继承 HttpBodyRecorderFilter，重写 recordBody 办法就能自定义本人的解决逻辑了。
另外，recordCode 办法可用于定义在申请响应码为多少的时候才会去记录 body，例如能够定义为只有遇到 400 或 500 时才记录 body，用于谬误侦测。
过滤器的匹配规定比较简单，如果想要像 springmvc 那样进行匹配，咱们能够应用：AntPathMatcher。
class PatternMappingFilterProxy implements Filter {
private final Filter delegate;
private final List<String> pathUrlPatterns = new ArrayList();
private PathMatcher pathMatcher;
public PatternMappingFilterProxy(Filter delegate, String... urlPatterns) {Assert.notNull(delegate, "A delegate Filter is required");
this.delegate = delegate;
int length = urlPatterns.length;
pathMatcher = new AntPathMatcher();
for (int index = 0; index < length; ++index) {String urlPattern = urlPatterns[index];
this.pathUrlPatterns.add(urlPattern);
}
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
throws IOException, ServletException {HttpServletRequest httpRequest = (HttpServletRequest) request;
String path = httpRequest.getRequestURI();
if (this.matches(path)) {this.delegate.doFilter(request, response, filterChain);
} else {filterChain.doFilter(request, response);
}
}
private boolean matches(String requestPath) {for (String pattern : pathUrlPatterns) {if (pathMatcher.match(pattern, requestPath)) {return true;}
}
return false;
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {this.delegate.init(filterConfig);
}
@Override
public void destroy() {this.delegate.destroy();
}
public List<String> getPathUrlPatterns() {return pathUrlPatterns;}
public void setPathUrlPatterns(List<String> urlPatterns) {pathUrlPatterns.clear();
pathUrlPatterns.addAll(urlPatterns);
}
}这样子，PatternMappingFilterProxy 装璜了真正的 HttpBodyRecorderFilter，反对传入 urlPatterns，从而实现像 springmvc 那样的 ant style 的匹配。例如对于以下接口：
@PostMapping("/test/{id}")
public Object test(@PathVariable(value = "id",required = true) final Integer index) {//do something}能够设置 urlPattern 为 /test/{id:[0-9]+}。
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