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摘要: 原创出处 fredal.xin/http-body-recorder 「fredalxin」欢迎转载,保留摘要,谢谢!


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经常会遇到需要处理http请求以及响应body的场景。而这里比较大的一个问题是servlet的requestBody或responseBody流一旦被读取了。就无法二次读取了。针对这个问题,spring本身提供了解决方案,即ContentCachingRequestWrapper/ContentCachingResponseWrapper。

我们编写一个过滤器:

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方法就能自定义自己的处理逻辑了。另外,recordCode方法可用于定义在请求响应码为多少的时候才会去记录body,例如可以定义为只有遇到400或500时才记录body,用于错误侦测。

PatternMappingFilterProxy

过滤器的匹配规则比较简单,如果想要像springmvc那样进行匹配,我们可以使用 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);
}

}

测试

这样子,PatternMappingFilterProxy装饰了真正的HttpBodyRecorderFilter,支持传入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
}

可以设置urlPattern为/test/{id:[0-9]+}

以上代码存在于httpBodyRecorder

文章目录
  1. 1. 我们编写一个过滤器:
  2. 2. PatternMappingFilterProxy
  3. 3. 测试