JS分块上传 formData到服务器的分块,直到所有的分块都上传完毕JS完整代码和 VB IHttpHandler后端完整代码
时间: 2024-10-14 08:16:34 浏览: 3
在JavaScript中,我们可以使用`fetch` API 或 `XMLHttpRequest` 实现文件分块上传。这里是一个简单的示例,展示了如何将FormData分割成多个小块并逐个发送:
```javascript
// 定义文件和分块大小
const file = document.querySelector('input[type=file]').files[0];
const blockSize = 1024 * 1024; // 1MB
function uploadChunk(formData, index) {
const xhr = new XMLHttpRequest();
xhr.open('POST', '/upload', true);
xhr.setRequestHeader('Content-Type', 'multipart/form-data');
xhr.onload = function() {
if (xhr.status === 200) {
console.log(`Block ${index} uploaded successfully.`);
if (index + 1 < getTotalChunks()) {
uploadNextChunk();
} else {
console.log('All chunks uploaded.');
}
} else {
console.error(`Error uploading block ${index}: ${xhr.statusText}`);
}
};
xhr.send(formData.slice(index * blockSize, (index + 1) * blockSize));
}
function getTotalChunks() {
return Math.ceil(file.size / blockSize);
}
let currentChunk = 0;
uploadNextChunk();
function uploadNextChunk() {
if (currentChunk < getTotalChunks()) {
const formData = new FormData();
formData.append('file', file, file.name);
uploadChunk(formData, currentChunk++);
}
}
```
对于VB .NET 的IHttpHandler后台处理,由于涉及到服务器端代码,这里提供一个基本的示例框架,你需要填充`UploadFile`函数的实现:
```vbnet
Imports System.IO
Imports Microsoft.VisualBasic.FileIO
Public Class FileUploadHandler : Inherits HttpHandler
Protected Async Sub ProcessRequestAsync()
Dim filePath As String = ""
Try
Dim fileBytes As Byte() = Await Request.InputStream.ReadAsByteArrayAsync()
Dim fileName As String = GetFileNameFromRequest(Request.Files(0))
filePath = SaveTempFile(fileName, fileBytes)
' 这里根据filePath处理文件,例如分块存储、数据库插入等操作
' 可能需要你自己实现SaveTempFile和UploadFile方法
Dim responseMessage As String = "File chunk processed."
If IsUploadedInPieces Then
' 如果需要分块,返回响应给前端告知进度
' 假设你有一个状态跟踪系统
Dim progress As Integer = CalculateProgress(filePath)
Return Content($"Progress: {progress}% - {responseMessage}")
Else
Return Content(responseMessage)
End If
Catch ex As Exception
Return Content("Error processing the file: " & ex.Message)
Finally
' 清理临时文件
RemoveFile(filePath)
End Try
End Sub
' 省略的辅助方法...
End Class
```
注意,这只是一个简化的版本,实际项目中还需要考虑错误处理、安全性以及服务器端文件管理等问题。