public static boolean checkIfNoneMatchEtag(HttpServletRequest request,
                                               HttpServletResponse response, String etag) {
    """
	根据浏览器 If-None-Match Header, 计算Etag是否已无效. <p/> 如果Etag有效, checkIfNoneMatch返回false, 设置304 not
	modify status.
	
	@param etag 内容的ETag.
    """
        String headerValue = request.getHeader(HttpHeaders.IF_NONE_MATCH);
        if (headerValue != null) {
            boolean conditionSatisfied = false;
            if (!StringPool.ASTERISK.equals(headerValue)) {
                StringTokenizer commaTokenizer = new StringTokenizer(headerValue, StringPool.COMMA);

                while (!conditionSatisfied && commaTokenizer.hasMoreTokens()) {
                    String currentToken = commaTokenizer.nextToken();
                    if (currentToken.trim().equals(etag)) {
                        conditionSatisfied = true;
                    }
                }
            } else {
                conditionSatisfied = true;
            }

            if (conditionSatisfied) {
                response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                response.setHeader(HttpHeaders.ETAG, etag);
                return false;
            }
        }
        return true;
    }
public static boolean checkIfNoneMatchEtag(HttpServletRequest request,
                                               HttpServletResponse response, String etag) {
        String headerValue = request.getHeader(HttpHeaders.IF_NONE_MATCH);
        if (headerValue != null) {
            boolean conditionSatisfied = false;
            if (!StringPool.ASTERISK.equals(headerValue)) {
                StringTokenizer commaTokenizer = new StringTokenizer(headerValue, StringPool.COMMA);

                while (!conditionSatisfied && commaTokenizer.hasMoreTokens()) {
                    String currentToken = commaTokenizer.nextToken();
                    if (currentToken.trim().equals(etag)) {
                        conditionSatisfied = true;
                    }
                }
            } else {
                conditionSatisfied = true;
            }

            if (conditionSatisfied) {
                response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                response.setHeader(HttpHeaders.ETAG, etag);
                return false;
            }
        }
        return true;
    }
public static boolean checkIfNoneMatchEtag ( HttpServletRequest request , HttpServletResponse response , String etag ) { String headerValue = request . getHeader ( HttpHeaders . IF_NONE_MATCH ) ; if ( headerValue != null ) { boolean conditionSatisfied = false ; if ( ! StringPool . ASTERISK . equals ( headerValue ) ) { StringTokenizer commaTokenizer = new StringTokenizer ( headerValue , StringPool . COMMA ) ; while ( ! conditionSatisfied && commaTokenizer . hasMoreTokens ( ) ) { String currentToken = commaTokenizer . nextToken ( ) ; if ( currentToken . trim ( ) . equals ( etag ) ) { conditionSatisfied = true ; } } } else { conditionSatisfied = true ; } if ( conditionSatisfied ) { response . setStatus ( HttpServletResponse . SC_NOT_MODIFIED ) ; response . setHeader ( HttpHeaders . ETAG , etag ) ; return false ; } } return true ; }
根据浏览器 If-None-Match Header, 计算Etag是否已无效. <p/> 如果Etag有效, checkIfNoneMatch返回false, 设置304 not
modify status.

@param etag 内容的ETag.
根据浏览器 If - None - Match Header 计算Etag是否已无效 . <p / > 如果Etag有效 checkIfNoneMatch返回false 设置304 not modify status .