OncePerRequestFilter不包含响应正文中的最后一个字符

Question

我正在尝试在REST api中实现内容摘要标头。当我为我的回复创建摘要时，它总是省略最后一个字符。

public class ContentDigestFilter扩展OncePerRequestFilter {

@Override
protected boolean shouldNotFilterAsyncDispatch() {
    return false;
}

@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
        throws ServletException, IOException {

    HttpServletResponse responseToUse = response;
    if (!isAsyncDispatch(request) && !(response instanceof ContentCachingResponseWrapper)) {
        responseToUse = new HttpStreamingAwareContentCachingResponseWrapper(response, request);
    }

    filterChain.doFilter(request, responseToUse);

    updateResponse(request, responseToUse);
}

private void updateResponse(HttpServletRequest request, HttpServletResponse response) throws IOException {
    ContentCachingResponseWrapper responseWrapper =
            WebUtils.getNativeResponse(response, ContentCachingResponseWrapper.class);
    Assert.notNull(responseWrapper, "ContentCachingResponseWrapper not found");
    HttpServletResponse rawResponse = (HttpServletResponse) responseWrapper.getResponse();
    int statusCode = responseWrapper.getStatusCode();

    if (rawResponse.isCommitted()) {
        responseWrapper.copyBodyToResponse();
    }
    else{
        String digest = getContentDigest(responseWrapper.getContentInputStream());

        rawResponse.setHeader("X-Digest",digest);
        responseWrapper.copyBodyToResponse();
    }
}


protected String getContentDigest(InputStream inputStream) throws IOException {

    try {
        byte[] dataArray = StreamUtils.copyToByteArray(inputStream);

        //dataArray doesn't include last character of response body.
        System.out.println("Response Body: " + new String(dataArray,"UTF-8"));

        String digest = ""; //Generate digest with HMAC-SHA512

        return digest;

    } catch (NoSuchAlgorithmException e) {
        throw new RuntimeException(e);
    } catch (InvalidKeyException e) {
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    return "NoDigest";
}

private static class HttpStreamingAwareContentCachingResponseWrapper extends ContentCachingResponseWrapper {

    private final HttpServletRequest request;

    public HttpStreamingAwareContentCachingResponseWrapper(HttpServletResponse response, HttpServletRequest request) {
        super(response);
        this.request = request;
    }

    @Override
    public ServletOutputStream getOutputStream() throws IOException {
        return super.getOutputStream();
    }

    @Override
    public PrintWriter getWriter() throws IOException {
        return super.getWriter();
    }
}

}

在方法getContentDigest中，如果我打印dataArray，它不包含响应的最后一个字符