当您将文件数据作为字节数组放入内存时，您对 Web 服务器施加了很大的压力。
与其将整个文件数据存储在字节数组中，不如尝试将文件流以块的形式写入响应流。
伪示例：
context.Response.Buffer = false;
byte[] buffer = new byte[4096];
int bytesRead = 0;
using(var stream = new FileStream(path, FileMode.Open, FileAccess.Read))
{
while ((bytesRead = stream.Read(buffer, 0 , buffer.Length)) > 0)
{
context.Response.OutputStream.Write(buffer, 0, buffer.Length);
context.Response.OutputStream.Flush();
}
}
这里的想法是，您只需在每次读取文件流时将一大块文件数据放入内存，然后将其写入响应。请注意，响应缓冲已被禁用，您可以使用文件流替换另一个 Stream 数据源（我在从 SQL 数据库读取二进制数据时使用了这种方法）。
编辑：（对如何将数据从 SQL 流式传输到 HTTP 响应的响应）
为了从 SQL Server 数据库表（例如 varbinary(max) 列）流式传输数据，您在 SqlCommand 上使用顺序访问：
#region WriteResponse(HttpContext context, Guid id)
/// <summary>
/// Writes the content for a media resource with the specified <paramref name="id"/>
/// to the response stream using the appropriate content type and length.
/// </summary>
/// <param name="context">The <see cref="HttpContext"/> to write content to.</param>
/// <param name="id">The unique identifier assigned to the media resource.</param>
private static void WriteResponse(HttpContext context, Guid id)
{
using(var connection = ConnectionFactory.Create())
{
using (var command = new SqlCommand("[dbo].[GetResponse]", connection))
{
command.CommandType = CommandType.StoredProcedure;
command.Parameters.Add("@Id", SqlDbType.UniqueIdentifier);
command.Parameters.AddReturnValue();
command.Parameters["@Id"].Value = id;
command.Open();
using(var reader = command.ExecuteReader(CommandBehavior.SequentialAccess))
{
if(reader.Read())
{
WriteResponse(context, reader);
}
}
}
}
}
#endregion
#region WriteResponse(HttpContext context, SqlDataReader reader)
/// <summary>
/// Writes the content for a media resource to the response stream using the supplied <paramref name="reader"/>.
/// </summary>
/// <param name="context">The <see cref="HttpContext"/> to write content to.</param>
/// <param name="reader">The <see cref="SqlDataReader"/> to extract information from.</param>
private static void WriteResponse(HttpContext context, SqlDataReader reader)
{
if (context == null || reader == null)
{
return;
}
DateTime expiresOn = DateTime.UtcNow;
string contentType = String.Empty;
long contentLength = 0;
string fileName = String.Empty;
string fileExtension = String.Empty;
expiresOn = reader.GetDateTime(0);
fileName = reader.GetString(1);
fileExtension = reader.GetString(2);
contentType = reader.GetString(3);
contentLength = reader.GetInt64(4);
context.Response.AddHeader("Content-Disposition", String.Format(null, "attachment; filename={0}", fileName));
WriteResponse(context, reader, contentType, contentLength);
ApplyCachePolicy(context, expiresOn - DateTime.UtcNow);
}
#endregion
#region WriteResponse(HttpContext context, SqlDataReader reader, string contentType, long contentLength)
/// <summary>
/// Writes the content for a media resource to the response stream using the
/// specified reader, content type and content length.
/// </summary>
/// <param name="context">The <see cref="HttpContext"/> to write content to.</param>
/// <param name="reader">The <see cref="SqlDataReader"/> to extract information from.</param>
/// <param name="contentType">The content type of the media.</param>
/// <param name="contentLength">The content length of the media.</param>
private static void WriteResponse(HttpContext context, SqlDataReader reader, string contentType, long contentLength)
{
if (context == null || reader == null)
{
return;
}
int ordinal = 5;
int bufferSize = 4096 * 1024; // 4MB
byte[] buffer = new byte[bufferSize];
long value;
long dataIndex;
context.Response.Buffer = false;
context.Response.ContentType = contentType;
context.Response.AppendHeader("content-length", contentLength.ToString());
using (var writer = new BinaryWriter(context.Response.OutputStream))
{
dataIndex = 0;
value = reader.GetBytes(ordinal, dataIndex, buffer, 0, bufferSize);
while(value == bufferSize)
{
writer.Write(buffer);
writer.Flush();
dataIndex += bufferSize;
value = reader.GetBytes(ordinal, dataIndex, buffer, 0, bufferSize);
}
writer.Write(buffer, 0, (int)value);
writer.Flush();
}
}
#endregion