我在捕获
HTML输出的动作上有以下过滤器,将其转换为字符串,执行一些操作以修改字符串,并返回带有新字符串的ContentResult.不幸的是,我一直以一个空字符串结束.
private class UpdateFilter : ActionFilterAttribute
{
private Stream stream;
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
stream = filterContext.HttpContext.Response.Filter;
stream = new MemoryStream();
filterContext.HttpContext.Response.Filter = stream;
}
public override void OnResultExecuted(ResultExecutedContext filterContext)
{
StreamReader responsereader = new StreamReader(filterContext.HttpContext.Response.Filter); //empty stream? why?
responsereader.BaseStream.Position = 0;
string response = responsereader.ReadToEnd();
ContentResult contres = new ContentResult();
contres.Content = response;
filterContext.Result = contres;
}
}
我已经确定了StreamReader(stream).ReadToEnd()返回一个空字符串,但我无法弄清楚原因.
任何想法如何解决这一问题？
编辑：我已经将OnActionExecuted更改为OnResultExecuted,现在在生成View之后调用它,但是流仍然是空的！
解决方法
我通过劫持HttpWriter解决了这个问题,并将其写入StringBuilder而不是响应,然后在将其写入输出之前执行需要对响应执行的任何操作.
private class UpdateFilter : ActionFilterAttribute
{
private HtmlTextWriter tw;
private StringWriter sw;
private StringBuilder sb;
private HttpWriter output;
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
sb = new StringBuilder();
sw = new StringWriter(sb);
tw = new HtmlTextWriter(sw);
output = (HttpWriter)filterContext.RequestContext.HttpContext.Response.Output;
filterContext.RequestContext.HttpContext.Response.Output = tw;
}
public override void OnResultExecuted(ResultExecutedContext filterContext)
{
string response = sb.ToString();
//response processing
output.Write(response);
}
}
