javascript - 在 JavaScript 中创建字节数组

Question

有没有办法从 JavaScript(或 Typescript)中的文件创建字节数组，该数组将发送到 C# WebApi 服务，并可由 C# 字节数组方法参数使用？如果是的话，您能提供一个 JavaScript 示例吗？

我应该提到，这是一个 Angular 4+ 应用程序，将发布到该服务。

我需要将Word文档、PDF和图像上传到C#服务，这就是C#服务目前的构建方式。它需要一个正在上传的文件的字节数组。

这是C#服务的请求对象:

[DataContract]
public class SaveAttachmentRequest : BaseRequest
{
    [RestUrlParameter(Mode = UrlParameterMode.Inline)]
    [DataMember(IsRequired = true)] public AttachmentLookupInformation LookupInformation { get; set; } = new AttachmentLookupInformation();
    [DataMember(IsRequired = true)] public byte[] Attachment { get; set; } = null;
}

这是 AttachmentLookupInformation 类:

[DataContract]
public class AttachmentLookupInformation
{
    [DataMember(IsRequired = true)] public Guid Id { get; set; } = Guid.Empty;
    [DataMember(IsRequired = true)] public Guid LinkedToId { get; set; } = Guid.Empty;
    ///<summary>Not including the path- just the file name and extension.</summary>
    [DataMember(IsRequired = true)] public string FileName { get; set; } = string.Empty;
    [DataMember(IsRequired = true)] public int FileSizeInBytes { get; set; } = 0;
    ///<summary>MIME type.</summary>
    [DataMember(IsRequired = true)] public string ContentType { get; set; } = string.Empty;
    [DataMember(IsRequired = true)] public AttachmentCategories AttachmentCategory { get; set; } = AttachmentCategories.Unknown;
    [DataMember(IsRequired = true)] public string DownloadUrl { get; set; } = string.Empty;
    [DataMember(IsRequired = true)] public string CreatedBy { get; set; } = string.Empty;
    [DataMember(IsRequired = true)] public DateTimeOffset CreatedTimestamp { get; set; } = DateTimeOffset.MinValue;
}

这样我就可以将文件和其他数据上传到服务。

编辑:包括我使用的失败的 Angular 代码:

const lookupInfo = new AttachmentLookupInformation();
lookupInfo.Id = Helpers.emptyGuid;
lookupInfo.LinkedToId = this.contractId;
lookupInfo.AttachmentCategory = 10;

const request = new SaveAttachmentRequest();

const reader = new FileReader();
reader.onload = function() {
  const buffer = reader.result;
  let binary = '';
  const bytes = new Uint8Array(buffer);
  const length = bytes.byteLength;
  for (let i = 0; i < length; i++) {
    binary += String.fromCharCode(bytes[i]);
  }

  request.Attachment = binary;
  lookupInfo.ContentType = files[0].type;
  lookupInfo.FileName = files[0].name;
  lookupInfo.FileSizeInBytes = length;
};
reader.readAsArrayBuffer(files[0]);
reader.onloadend = function() {
  request.LookupInformation = lookupInfo;

  console.log('request: ', request);

  that.contractsService
    .save(request, 'attachment/saveattachment')
    .subscribe(res => {
      if (res.Success) {
        console.log('upload response: ', res);
      }
    });

};

Answer 1

那么，你有:

that.contractsService
    .save(request, 'attachment/saveattachment')

但是您显示的类是 SaveAttachmentRequest，其中包含 public byte[] Attachment。您的问题中没有显示名为 attachment 的类中名为 saveattachment 的函数，该函数应该处理将数据传输到 byte[] 的操作，我想，除非你以某种方式将其直接设置到参数中。假设您有这样一个 attachment 类，那么您应该在其中有一个名为 saveattachment 的入口点来完成所有工作。但可以说它失败了，因为您正在传递 JS 模型并将其直接映射到 .NET 模型。然后创建一个可以接受二进制字符串的字符串参数，然后将其保存到您的 byte[] 参数中。

[DataMember(IsRequired = true)] public string strAttachment { get; set; } = null;

在你的 JS 中，

request.Attachment = binary;

变成了

request.strAttachment = binary;

那么你需要:

public class attachment : ApiController
{
    [System.Web.Http.HttpPost]
    public JsonResult saveattachment(SaveAttachmentRequest sar, AttachmentLookupInformation ali)
    {          
        //string bits = "000011110000001000";
        string bits = sar.strAttachment;
        int numOfBytes = (int)Math.Ceiling(bits.Length / 8m);
        byte[] bytes = new byte[numOfBytes];
        int chunkSize = 8;

        for (int i = 1; i <= numOfBytes; i++)
        {
            int startIndex = bits.Length - 8 * i;
            if (startIndex < 0)
            {
                chunkSize = 8 + startIndex;
                startIndex = 0;
            }
            bytes[numOfBytes - i] = Convert.ToByte(bits.Substring(startIndex, chunkSize), 2);
        }

        sar.attachment = bytes;

        // ... do your other stuff for saving your model objects to the DB
        // using Entity Framework's data context, etc.
    }
}

这只是将二进制字符串转换为 byte[] 的一种方法。还有很多其他方式here .

或者，您是否尝试过将其作为字符串发送，从而实现:

[DataMember(IsRequired = true)] public byte[] Attachment { get; set; } = null;

变成这样:

[DataMember(IsRequired = true)] public string Attachment { get; set; } = null;

首先？