.NET Core 2
客户端在尝试向服务器发送get请求时立即死亡。如果我使用Postman那么它工作正常，但我需要通过C＃来完成。这是我的代码片段，用于从服务器获取文件：
var client = new HttpClient();
client.Timeout = TimeSpan.FromMinutes(timeSpanFromMinutes);
try
{
// At this code row the application shutdown without any exception.
// Even doesn't work the 'catch' block of try\catch...
HttpResponseMessage response = await client.GetAsync(url + "/Home/Download/" + args[1],
HttpCompletionOption.ResponseContentRead);
// I will not be here
Console.WriteLine("Response status code: {0}", response.StatusCode);
if (response.StatusCode == HttpStatusCode.OK)
{
using (MemoryStream ms = new MemoryStream())
{
await response.Content.CopyToAsync(ms);
Console.WriteLine("Data successfully recieved from server. Data length: {0}",
ms.Length);
string resultFileName = Path.Combine(resultFolder, new Guid().ToString()
+ resultFileExtension);
using (FileStream fs = new FileStream(resultFileName, FileMode.Create))
{
fs.Read(ms.GetBuffer(), 0, (int) ms.Length);
}
Console.WriteLine("The result was saved in the '{0}' file.", resultFileName);
}
}
}
catch (Exception ex)
{ // I will not be here
Console.WriteLine("Exception: {0}", ex.Message);
}
启动并可访问服务器。初始化所有变量并使有效值满足。 post请求可以正常运行。我有get请求的问题。我评论了问题代码行。
这种行为的原因是什么？
UPD
这是我的客户端的完整代码（问题是“get”命令）：
using System;
using System.IO;
using System.Net;
using System.Net.Http;
using System.Reflection;
using System.Threading.Tasks;
using System.Xml.Linq;
namespace Client
{
class Program
{
static void Main(string[] args)
{
var task = Task.Run(()=>{
Work(args);
});
task.Wait();
}
static async Task Work(string[] args)
{
if (args.Length != 2)
{
Console.WriteLine("Application invalid parameters.");
WriteHelp();
return;
}
string xmlFileName = Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location),
"Client.settings.xml");
XElement xml = XElement.Load(xmlFileName);
string url = xml.Element("url").Value?.Trim()?.TrimEnd('/');
string resultFolder = Environment.ExpandEnvironmentVariables(xml.Element("resultsFolder").Value);
if (!Directory.Exists(resultFolder))
{
Directory.CreateDirectory(resultFolder);
}
string resultFileExtension = Environment.ExpandEnvironmentVariables(xml.Element("resultFileExtension").Value);
int timeSpanFromMinutes = Int32.Parse(xml.Element("TimeSpanFromMinutes").Value);
switch (args[0])
{
// Send data to server
case "post":
{
string fileName = Environment.ExpandEnvironmentVariables(args[1]);
if (!File.Exists(fileName))
{
Console.WriteLine("File '{0}' not found.", fileName);
return;
}
else
{
var client = new HttpClient();
client.Timeout = TimeSpan.FromMinutes(timeSpanFromMinutes);
try
{
using (FileStream fs = new FileStream(fileName, FileMode.Open))
{
HttpResponseMessage response = await client.PostAsync(url + "/Home/Upload",
new StreamContent(fs));
Console.WriteLine("Response status code: {0}", response.StatusCode);
if (response.StatusCode == HttpStatusCode.OK)
{
// The task ID. It is to be used for get the data handling result from server later.
string id = await response.Content.ReadAsStringAsync();
Console.WriteLine("Task ID: {0}", id);
}
}
}
catch (Exception ex)
{
Console.WriteLine("Exception: {0}", ex.Message);
}
}
break;
}
// get the result of data handling from server
case "get":
{
Guid guid = Guid.Empty;
if (!Guid.TryParse(args[1], out guid))
{
Console.WriteLine("Invalid identifier (GUID): '{0}'", args[1]);
return;
}
var client = new HttpClient();
client.Timeout = TimeSpan.FromMinutes(timeSpanFromMinutes);
try
{
// TODO: the problem is here
var response = await client.GetAsync(url + "/Home/Download/" + args[1],
HttpCompletionOption.ResponseContentRead);
Console.WriteLine("Response status code: {0}", response.StatusCode);
if (response.StatusCode == HttpStatusCode.OK)
{
using (MemoryStream ms = new MemoryStream())
{
await response.Content.CopyToAsync(ms);
Console.WriteLine("Data successfully recieved from server. Data length: {0}",
ms.Length);
string resultFileName = Path.Combine(resultFolder, new Guid().ToString()
+ resultFileExtension);
using (FileStream fs = new FileStream(resultFileName, FileMode.Create))
{
fs.Read(ms.GetBuffer(), 0, (int) ms.Length);
}
Console.WriteLine("The result was saved in the '{0}' file.", resultFileName);
}
}
}
catch (Exception ex)
{
Console.WriteLine("Exception: {0}", ex.Message);
}
break;
}
default:
{
Console.WriteLine("Unknown command: {0}", args[0]);
WriteHelp();
return;
}
}
}
private static void WriteHelp()
{
string text =
@"
Client.dll
(c) Andrey Bushman, 2018
This client allows to send data to server and get the results of their handling.
The application using format:
dotnet Client.dll <command> <parameter>
## COMMAND
post - send file to server. The request contains status code and GUID for getting the data handling result later.
get - get data handling result by GUID. If result doesn't exist still then recuest code is 'File not found'.
## PARAMETER
It is the file full name for the 'post' command or the GUID for the 'get' command.
## EXAMPLES
Upload the file to server:
dotnet Client.dll post /home/andrey/tmp/data.foo
Download the data handling result from server by GUID:
dotnet Client.dll get 3d600895-f11c-4fa0-865e-411d52daf469";
Console.WriteLine(text);
}
}
}
GitHub上的完整代码源为here。
答案 0 :(得分：3)
注意编译器警告：
var task = Task.Run(()=>{
Work(args);
});
task.Wait();
它应该告诉你这里没有等待Work(args)。这意味着它抛出的任何一个切除都是未被观察到的。
由于我们使用的是控制台应用，Task.Run()没有任何实际用途
请改用以下内容：
static void Main(string[] args)
{
try
{
var task = Work(args);
task.Wait();
}
catch (Exception ex)
{
// log or put a breakpoint here
}
}