MVC 3压缩过滤器导致输出乱码

Question

因此，我有一个名为CompressAttribute的自定义属性，它在global.asax中设置为全局筛选器。它使用反射来检查当前操作方法的返回类型，如果是"ViewResult“，则使用GZip或Deflate压缩输出。它工作得很好，除非一个页面抛出了一个500Server错误。如果遇到错误，我得到的不是.NET错误页面，而是一堆这样的内容：

��������`I�%&/m�{J�J��t��

显然，它试图编码500服务器错误页面，这是导致问题的原因。处理这个问题的最好方法是什么？

下面是过滤器代码：

public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            MethodInfo actionMethodInfo = Common.GetActionMethodInfo(filterContext);
            if (GetReturnType(actionMethodInfo).ToLower() != "viewresult") return;

            HttpRequestBase request = filterContext.HttpContext.Request;

            string acceptEncoding = request.Headers["Accept-Encoding"];

            if (string.IsNullOrEmpty(acceptEncoding)) return;

            acceptEncoding = acceptEncoding.ToUpperInvariant();

            HttpResponseBase response = filterContext.HttpContext.Response;

            if (acceptEncoding.Contains("GZIP"))
            {
                response.AppendHeader("Content-encoding", "gzip");
                response.Filter = new WebCompressionStream(response.Filter, CompressionType.GZip);
            }
            else if (acceptEncoding.Contains("DEFLATE"))
            {
                response.AppendHeader("Content-encoding", "deflate");
                response.Filter = new WebCompressionStream(response.Filter, CompressionType.Deflate);
            }
        }

Answer 1

好的，我可以通过清除Application_Error事件中的Response.Filter属性来解决这个问题：

public void Application_Error(object sender, EventArgs e)
{
    Response.Filter.Dispose();
}

想知道有没有更正确的方法...

Answer 2

您也可以通过附加到OnResultExecuting而不是OnActionExecuting来解决此问题。这提供了一些优势

在不求助于reflection.

• OnResultExecuting的情况下，您可以发现操作结果在异常情况下不会执行(MVC将调用OnException，但不调用

如下所示：

public sealed class MyAttribute  : ActionFilterAttribute
{
    /// <summary>
    /// Called by MVC just before the result (typically a view) is executing.
    /// </summary>
    /// <param name="filterContext"></param>
    public override void OnResultExecuting(ResultExecutingContext filterContext)
    {
        var result = filterContext.Result;
        if (result is ViewResultBase)
        {
            var response = filterContext.HttpContext.Response;

            // Check your request parameters and attach filter.
        }
    }

Answer 3

如果已经向输出中写入了任何内容，则接受的答案将不起作用。

您可以确保在适当的位置持久化消息头，而不是处理过滤器：

 protected void Application_PreSendRequestHeaders()
{
    // ensure that if GZip/Deflate Encoding is applied that headers are set
    // also works when error occurs if filters are still active
    HttpResponse response = HttpContext.Current.Response;
    if (response.Filter is GZipStream && response.Headers["Content-encoding"] != "gzip")
        response.AppendHeader("Content-encoding", "gzip");
    else if (response.Filter is DeflateStream && response.Headers["Content-encoding"] != "deflate")
        response.AppendHeader("Content-encoding", "deflate");
}