asp.net web api 文件上传

1正确的做法

public class AvaterController : BaseApiController
{
[HttpPost]
        public async Task<IHttpActionResult> UploadAvater(int userId)
        {
            AvatarBLL pictureBLL = new AvatarBLL(this.Request);
            await pictureBLL.UploadAvatar(userId);
            return Ok();
     }

//其他Action
}

public class AvatarBLL
{
private HttpRequestMessage HttpRequestMessage;
public AvatarBLL(HttpRequestMessage httpRequestMessage)
{
     this.HttpRequestMessage = httpRequestMessage;
}
public async Task UploadAvatar(int userId)
        {
            if (!HttpRequestMessage.Content.IsMimeMultipartContent("form-data"))
            {
                //抛异常
            }
//获得客户端传递到服务器的数据
            List<byte> list = new List<byte>();
            await HttpRequestMessage.Content.ReadAsMultipartAsync().ContinueWith(multipartContent =>
            {
                if (multipartContent.IsFaulted || multipartContent.IsCanceled)
                {
                    //抛异常
                }

                foreach (var content in multipartContent.Result.Contents)
                {
                    var b = content.ReadAsByteArrayAsync().Result;
                    list.AddRange(b);
                }
         });

//其他部分（将数据存入Mongodb以及其他的业务逻辑）
}

}

2错误的做法

public class AvaterController : BaseApiController
{
[HttpPost]
        public IHttpActionResult UploadAvater(int userId)
        {
            AvatarBLL pictureBLL = new AvatarBLL(this.Request);
            pictureBLL.UploadAvatar(userId);
            return Ok();
     }

//其他Action
}
public class AvatarBLL
{
private HttpRequestMessage HttpRequestMessage;
public AvatarBLL(HttpRequestMessage httpRequestMessage)
{
     this.HttpRequestMessage = httpRequestMessage;
}
public void UploadAvatar(int userId)
        {
            if (!HttpRequestMessage.Content.IsMimeMultipartContent("form-data"))
            {
                //抛异常
            }
//获得客户端传递到服务器的数据
            List<byte> list = new List<byte>();
            MemoryStream ms = new MemoryStream();
            try
            {
                 MultipartMemoryStreamProvider mmsp = new MultipartMemoryStreamProvider();
                 var task =                          HttpRequestMessage.Content.ReadAsMultipartAsync<MultipartMemoryStreamProvider>(mmsp, 100000);
                 task.Wait();
                 var contents = task.Result.Contents;

                 foreach (var c in contents)
                 {
                    var b = c.ReadAsByteArrayAsync();
                    b.Wait();
                    list.AddRange(b.Result);
                 }
              }
              catch (AggregateException ex)
                 { }

//其他部分（将数据存入Mongodb以及其他的业务逻辑）
}
}

3 错误现象：

采用第二种方式，如果客户端上传到服务的数据量（调用UploadAvater上传的数据）小于服务端设置的缓冲区的大小，那么可正常上传文件，如果大于服务端设置的缓冲区的大小，则无法正常上传，调试服务端代码，当执行到task.Wait();这行语句时，客户端一直等待，直到客户端调用超时，永远也无法返回调用结果，发生了死锁！！！使用HttpRequestMessage.Content.ReadAsMultipartAsync<MultipartMemoryStreamProvider>(mmsp, 1000);设置缓冲区大小为1000bit。这个方法有几个重载的方法，其中一个是不显示设置缓冲区大小，那么缓冲区大小为默认的。

4 对第二种方法的错误点分析：

看Web api dll源码中的设置：