如何实例化HttpPostedFile

Question

我正在尝试与一个我无法控制的系统进行通信,但是其中一个方法需要一个HttpPostedFile,我的代码中有一个字节数组.有没有人有一个实例化HttpPostedFile的例子,因为我知道它的构造函数是内部的？

我发现的最好的是这个SO帖子使用反射然而他们被引导到另一个方向,我不能采取,因为我无法修改第三方系统方法签名.

Answer 1

这真的是非常hacky代码,但以下似乎对我有用:

public HttpPostedFile ConstructHttpPostedFile(byte[] data, string filename, string contentType) {
  // Get the System.Web assembly reference
  Assembly systemWebAssembly = typeof (HttpPostedFileBase).Assembly;
  // Get the types of the two internal types we need
  Type typeHttpRawUploadedContent = systemWebAssembly.GetType("System.Web.HttpRawUploadedContent");
  Type typeHttpInputStream = systemWebAssembly.GetType("System.Web.HttpInputStream");

  // Prepare the signatures of the constructors we want.
  Type[] uploadedParams = { typeof(int), typeof(int) };
  Type[] streamParams = {typeHttpRawUploadedContent, typeof (int), typeof (int)};
  Type[] parameters = { typeof(string), typeof(string), typeHttpInputStream };

  // Create an HttpRawUploadedContent instance
  object uploadedContent = typeHttpRawUploadedContent
    .GetConstructor(BindingFlags.NonPublic | BindingFlags.Instance, null, uploadedParams, null)
    .Invoke(new object[]{data.Length, data.Length});

  // Call the AddBytes method
  typeHttpRawUploadedContent
    .GetMethod("AddBytes", BindingFlags.NonPublic | BindingFlags.Instance)
    .Invoke(uploadedContent, new object[] {data, 0, data.Length});

  // This is necessary if you will be using the returned content (ie to Save)
  typeHttpRawUploadedContent
    .GetMethod("DoneAddingBytes", BindingFlags.NonPublic | BindingFlags.Instance)
    .Invoke(uploadedContent, null);

  // Create an HttpInputStream instance
  object stream = (Stream)typeHttpInputStream
    .GetConstructor(BindingFlags.NonPublic | BindingFlags.Instance, null, streamParams, null)
    .Invoke(new object[] {uploadedContent, 0, data.Length});

  // Create an HttpPostedFile instance
  HttpPostedFile postedFile = (HttpPostedFile)typeof(HttpPostedFile)
    .GetConstructor(BindingFlags.NonPublic | BindingFlags.Instance, null, parameters, null)
    .Invoke(new object[] {filename, contentType, stream});

  return postedFile;
}

Answer 2

你可以试试

 var constructorInfo = typeof(HttpPostedFile).GetConstructors(BindingFlags.NonPublic | BindingFlags.Instance)[0];
 var obj = (HttpPostedFile)constructorInfo
           .Invoke(new object[] { "filename", "image/jpeg", null });

obj会的类型HttpPostedFile。我将最后一个参数设置为空，但它必须是一个 HttpInputStream 。