.NET Framework4.8下RestSharp+Polly获取序列化请求体并实现Gzip压缩

方法一：手动序列化+压缩（最直接可控） #

跳过RestSharp自动序列化流程，自己完成对象序列化、Gzip压缩，再将压缩后的内容作为请求体提交，彻底避免内容追加和重试异常问题：

1. 序列化请求对象为JSON字符串：

' 假设你的请求数据对象是 requestData
Dim serializer As New RestSharp.Serializers.JsonSerializer()
serializer.ContentType = "application/json"
Dim serializedBody As String = serializer.Serialize(requestData)

2. 执行Gzip压缩：

Dim compressedBytes As Byte()
Using dataStream As New MemoryStream()
    Using zipStream As New System.IO.Compression.GZipStream(dataStream, System.IO.Compression.CompressionMode.Compress)
        Using writer As New StreamWriter(zipStream)
            writer.Write(serializedBody)
        End Using
    End Using
    compressedBytes = dataStream.ToArray()
End Using

3. 构建请求并结合Polly重试：

Dim request As New RestRequest(Method.POST)
' 设置请求头
request.AddHeader("Content-Encoding", "gzip")
request.AddHeader("Content-Type", "application/json")
' 添加压缩后的请求体
request.AddParameter("application/x-gzip", compressedBytes, ParameterType.RequestBody)

' Polly重试策略示例
Dim retryPolicy = Policy.Handle(Of Exception)().Retry(2)
Dim restResponse As IRestResponse = retryPolicy.Execute(Function() client.Post(request))

这种方式完全由你控制序列化和压缩逻辑，每次重试都会重新生成完整的请求内容，不会出现流消耗或内容追加问题。

方法二：拦截RestSharp自动序列化后的内容并替换 #

如果必须依赖RestSharp自动序列化，可通过OnBeforeRequest拦截原始内容并替换，但需注意重置流位置避免异常：

request.OnBeforeRequest = Async Function(httpRequestMessage)
    ' 读取原始序列化内容
    Dim originalContent As String = Await httpRequestMessage.Content.ReadAsStringAsync()
    ' 重置流缓存，避免后续读取失败
    Await httpRequestMessage.Content.LoadIntoBufferAsync()
    
    ' 压缩原始内容
    Dim compressedBytes As Byte()
    Using dataStream As New MemoryStream()
        Using zipStream As New System.IO.Compression.GZipStream(dataStream, System.IO.Compression.CompressionMode.Compress)
            Using writer As New StreamWriter(zipStream)
                writer.Write(originalContent)
            End Using
        End Using
        compressedBytes = dataStream.ToArray()
    End Using
    
    ' 完全替换为压缩后的内容
    httpRequestMessage.Content = New ByteArrayContent(compressedBytes)
    ' 更新请求头
    httpRequestMessage.Content.Headers.ContentEncoding.Add("gzip")
    httpRequestMessage.Content.Headers.ContentType = New System.Net.Http.Headers.MediaTypeHeaderValue("application/json")
End Function

核心注意事项 #

• 必须调用LoadIntoBufferAsync()，因为ReadAsStringAsync()会消耗流，重置后才能确保重试时流可正常读取。
• Polly重试时会重新触发OnBeforeRequest，每次都会重新执行压缩逻辑，避免复用已消耗的流导致请求失败。

内容的提问来源于stack exchange，提问作者Lyra Leo