java - Spring Boot 在无效的 If-Modified-Since 值上抛出异常

Question

抱歉，如果这是错误的地方。

根据定义的 http 规范:https://www.rfc-editor.org/rfc/rfc7232#section-3.3

A recipient MUST ignore the If-Modified-Since header field if the received field-value is not a valid HTTP-date, or if the request method is neither GET nor HEAD.

Spring Boot 不会这样做。它抛出一个 IllegalArgumentException，检查 header 值的代码未处理该异常。

这里是org.springframework.http.HttpHeaders.java中的转换代码

/**
 * Return the value of the {@code If-Modified-Since} header.
 * <p>The date is returned as the number of milliseconds since
 * January 1, 1970 GMT. Returns -1 when the date is unknown.
 */
public long getIfModifiedSince() {
    return getFirstDate(IF_MODIFIED_SINCE);
}

/**
 * Parse the first header value for the given header name as a date,
 * return -1 if there is no value, or raise {@link IllegalArgumentException}
 * if the value cannot be parsed as a date.
 */
public long getFirstDate(String headerName) {
    String headerValue = getFirst(headerName);
    if (headerValue == null) {
        return -1;
    }
    for (String dateFormat : DATE_FORMATS) {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat(dateFormat, Locale.US);
        simpleDateFormat.setTimeZone(GMT);
        try {
            return simpleDateFormat.parse(headerValue).getTime();
        }
        catch (ParseException ex) {
            // ignore
        }
    }
    throw new IllegalArgumentException("Cannot parse date value \"" + headerValue +
            "\" for \"" + headerName + "\" header");
}

因此，如果您发送 header If-Modified-Since:0，您将得到一个异常，而不是返回 http 规范中定义的新 GET 响应。

还有其他人认为这是一个问题吗？

Answer 1

我最近看到了这个 created a ticket和 submitted a PR修复它与此同时，您可以使用过滤器删除 header 来解决此问题，例如

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

    HttpServletRequestWrapper wrapper = new HttpServletRequestWrapper((HttpServletRequest) request) {

        @Override
        public Enumeration<String> getHeaderNames() {
            List<String> hdrs = Collections.list(super.getHeaderNames())
                    .stream()
                    .filter(h -> !h.equals(IF_MODIFIED_SINCE))
                    .collect(Collectors.toList());

            return Collections.enumeration(hdrs);
        }
    };
    chain.doFilter(wrapper, response);
}