# 问题
是这样的，我.net core 2.1的项目，读取、获取Post请求内容的一段代码，大概这样：
```
[HttpPost]
public async Task Test([FromBody]string postStr)
{
using (var reader = new StreamReader(Request.Body, System.Text.Encoding.UTF8))
{
reader.BaseStream.Seek(0, SeekOrigin.Begin); //大概是== Request.Body.Position = 0;的意思
var readerStr = await reader.ReadToEndAsync();
reader.BaseStream.Seek(0, SeekOrigin.Begin); //读完后也复原
return Ok(readerStr);
}
}
```
但这段代码 在 .net core 3.1.0 和 .net core 3.1.2(没错特地升级过) 都读不到、获取不到Post的内容：
```
curl --location --request POST 'http://localhost:5001/api/TestPostReader/test' \
--header 'Content-Type: application/json' \
--data-raw '{"name":"hei"}'
```
报异常：
```
System.NotSupportedException: Specified method is not supported.
at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpRequestStream.Seek(Int64 offset, SeekOrigin origin)
at Push.WebApi.Controllers.TestPostReaderController.Test() in D:\工作\39\solution-push\Push.WebApi\Controllers\TestPostReaderController.cs:line 21
at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.TaskOfIActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.g__Logged|12_1(ControllerActionInvoker invoker)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Logged|17_1(ResourceInvoker invoker)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
```
# 解决
StartUp Configure 这里改成这样：
```
app.Use((context, next) =>
{
context.Request.EnableBuffering();
return next();
});
//这个在后边
app.UseRouting();
```
搞定：
问题不大，不过不想让大家重复趟坑。
参考自：
