C# 如何向Console.ReadLine（）添加超时？
我有一个控制台应用程序，我想给用户x秒的时间来响应提示。如果在一段时间后没有输入，程序逻辑应继续。我们假设超时意味着空响应C# 如何向Console.ReadLine（）添加超时？,c#,.net,console,timeout,io,C#,.net,Console,Timeout,Io,我有一个控制台应用程序，我想给用户x秒的时间来响应提示。如果在一段时间后没有输入，程序逻辑应继续。我们假设超时意味着空响应 最直接的方法是什么？我认为您需要创建一个辅助线程，并在控制台上轮询一个键。我知道没有内置的方法来实现这一点。我认为您需要创建一个辅助线程，并在控制台上轮询一个键。我知道没有内置的方法来实现这一点。这种方法是否需要帮助 这种方法会有帮助吗 无论如何，你确实需要第二个线程。您可以使用异步IO来避免声明自己的IO： 声明ManualResetEvent，称之为“evt” 调用S
最直接的方法是什么？我认为您需要创建一个辅助线程，并在控制台上轮询一个键。我知道没有内置的方法来实现这一点。我认为您需要创建一个辅助线程，并在控制台上轮询一个键。我知道没有内置的方法来实现这一点。这种方法是否需要帮助 这种方法会有帮助吗
无论如何，你确实需要第二个线程。您可以使用异步IO来避免声明自己的IO：
- 声明ManualResetEvent，称之为“evt”
- 调用System.Console.OpenStandardInput以获取输入流。指定将存储其数据并设置evt的回调方法
- 调用该流的BeginRead方法以启动异步读取操作
- 然后在ManualReset事件上输入定时等待
- 如果等待超时，则取消读取
如果读取返回数据，设置事件，主线程将继续，否则超时后将继续。无论如何，您确实需要第二个线程。您可以使用异步IO来避免声明自己的IO：
- 声明ManualResetEvent，称之为“evt”
- 调用System.Console.OpenStandardInput以获取输入流。指定将存储其数据并设置evt的回调方法
- 调用该流的BeginRead方法以启动异步读取操作
- 然后在ManualReset事件上输入定时等待
- 如果等待超时，则取消读取
如果读取返回数据，设置事件，主线程将继续，否则，您将在超时后继续。获取第二个线程的另一种廉价方法是将其包装在代理中。获取第二个线程的另一种廉价方法是将其包装在代理中。编辑：通过将实际工作在单独的进程中完成并在该进程超时时终止该进程来修复此问题。详情见下文。唷 只是试了一下，似乎效果不错。我的同事有一个使用Thread对象的版本，但我发现委托类型的BeginInvoke（）方法更优雅一些
namespace TimedReadLine
{
public static class Console
{
private delegate string ReadLineInvoker();
public static string ReadLine(int timeout)
{
return ReadLine(timeout, null);
}
public static string ReadLine(int timeout, string @default)
{
using (var process = new System.Diagnostics.Process
{
StartInfo =
{
FileName = "ReadLine.exe",
RedirectStandardOutput = true,
UseShellExecute = false
}
})
{
process.Start();
var rli = new ReadLineInvoker(process.StandardOutput.ReadLine);
var iar = rli.BeginInvoke(null, null);
if (!iar.AsyncWaitHandle.WaitOne(new System.TimeSpan(0, 0, timeout)))
{
process.Kill();
return @default;
}
return rli.EndInvoke(iar);
}
}
}
}
namespace ReadLine
{
internal static class Program
{
private static void Main()
{
System.Console.WriteLine(System.Console.ReadLine());
}
}
}
编辑：通过在单独的进程中完成实际工作并在该进程超时时终止该进程，修复了该问题。详情见下文。唷 只是试了一下，似乎效果不错。我的同事有一个使用Thread对象的版本，但我发现委托类型的BeginInvoke（）方法更优雅一些
namespace TimedReadLine
{
public static class Console
{
private delegate string ReadLineInvoker();
public static string ReadLine(int timeout)
{
return ReadLine(timeout, null);
}
public static string ReadLine(int timeout, string @default)
{
using (var process = new System.Diagnostics.Process
{
StartInfo =
{
FileName = "ReadLine.exe",
RedirectStandardOutput = true,
UseShellExecute = false
}
})
{
process.Start();
var rli = new ReadLineInvoker(process.StandardOutput.ReadLine);
var iar = rli.BeginInvoke(null, null);
if (!iar.AsyncWaitHandle.WaitOne(new System.TimeSpan(0, 0, timeout)))
{
process.Kill();
return @default;
}
return rli.EndInvoke(iar);
}
}
}
}
namespace ReadLine
{
internal static class Program
{
private static void Main()
{
System.Console.WriteLine(System.Console.ReadLine());
}
}
}
顺便说一句，上面的代码中有一个bug。通过调用waitHandle.Close（）可以从工作线程下关闭事件。如果用户在超时过期后点击“enter”，工作线程将尝试向抛出ObjectDisposedException的事件发送信号。异常是从工作线程抛出的，如果您没有设置未处理的异常处理程序，您的进程将终止。我可能对这个问题读得太多了，但我假设等待类似于启动菜单，除非您按键，否则它将等待15秒。您可以使用（1）阻塞函数或（2）线程、事件和计时器。该事件将充当“继续”，并将一直阻止，直到计时器过期或按键 （1）的伪代码为：
// Get configurable wait time
TimeSpan waitTime = TimeSpan.FromSeconds(15.0);
int configWaitTimeSec;
if (int.TryParse(ConfigManager.AppSetting["DefaultWaitTime"], out configWaitTimeSec))
waitTime = TimeSpan.FromSeconds(configWaitTimeSec);
bool keyPressed = false;
DateTime expireTime = DateTime.Now + waitTime;
// Timer and key processor
ConsoleKeyInfo cki;
// EDIT: adding a missing ! below
while (!keyPressed && (DateTime.Now < expireTime))
{
if (Console.KeyAvailable)
{
cki = Console.ReadKey(true);
// TODO: Process key
keyPressed = true;
}
Thread.Sleep(10);
}
//获取可配置的
using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
namespace PipedInfo
{
class Program
{
static void Main(string[] args)
{
StreamReader buffer = ReadPipedInfo();
Console.WriteLine(buffer.ReadToEnd());
}
#region ReadPipedInfo
public static StreamReader ReadPipedInfo()
{
//call with a default value of 5 milliseconds
return ReadPipedInfo(5);
}
public static StreamReader ReadPipedInfo(int waitTimeInMilliseconds)
{
//allocate the class we're going to callback to
ReadPipedInfoCallback callbackClass = new ReadPipedInfoCallback();
//to indicate read complete or timeout
AutoResetEvent readCompleteEvent = new AutoResetEvent(false);
//open the StdIn so that we can read against it asynchronously
Stream stdIn = Console.OpenStandardInput();
//allocate a one-byte buffer, we're going to read off the stream one byte at a time
byte[] singleByteBuffer = new byte[1];
//allocate a list of an arbitary size to store the read bytes
List<byte> byteStorage = new List<byte>(4096);
IAsyncResult asyncRead = null;
int readLength = 0; //the bytes we have successfully read
do
{
//perform the read and wait until it finishes, unless it's already finished
asyncRead = stdIn.BeginRead(singleByteBuffer, 0, singleByteBuffer.Length, new AsyncCallback(callbackClass.ReadCallback), readCompleteEvent);
if (!asyncRead.CompletedSynchronously)
readCompleteEvent.WaitOne(waitTimeInMilliseconds);
//end the async call, one way or another
//if our read succeeded we store the byte we read
if (asyncRead.IsCompleted)
{
readLength = stdIn.EndRead(asyncRead);
if (readLength > 0)
byteStorage.Add(singleByteBuffer[0]);
}
} while (asyncRead.IsCompleted && readLength > 0);
//we keep reading until we fail or read nothing
//return results, if we read zero bytes the buffer will return empty
return new StreamReader(new MemoryStream(byteStorage.ToArray(), 0, byteStorage.Count));
}
private class ReadPipedInfoCallback
{
public void ReadCallback(IAsyncResult asyncResult)
{
//pull the user-defined variable and strobe the event, the read finished successfully
AutoResetEvent readCompleteEvent = asyncResult.AsyncState as AutoResetEvent;
readCompleteEvent.Set();
}
}
#endregion ReadPipedInfo
}
}
string ReadLine(int timeoutms)
{
ReadLineDelegate d = Console.ReadLine;
IAsyncResult result = d.BeginInvoke(null, null);
result.AsyncWaitHandle.WaitOne(timeoutms);//timeout e.g. 15000 for 15 secs
if (result.IsCompleted)
{
string resultstr = d.EndInvoke(result);
Console.WriteLine("Read: " + resultstr);
return resultstr;
}
else
{
Console.WriteLine("Timed out!");
throw new TimedoutException("Timed Out!");
}
}
delegate string ReadLineDelegate();
Thread readKeyThread = new Thread(ReadKeyMethod);
static ConsoleKeyInfo cki = null;
void Main()
{
readKeyThread.Start();
bool keyEntered = false;
for(int ii = 0; ii < 10; ii++)
{
Thread.Sleep(1000);
if(readKeyThread.ThreadState == ThreadState.Stopped)
keyEntered = true;
}
if(keyEntered)
{ //do your stuff for a key entered
}
}
void ReadKeyMethod()
{
cki = Console.ReadKey();
}
while (Console.KeyAvailable == false)
{
Thread.Sleep(250);
i++;
if (i > 3)
throw new Exception("Timedout waiting for input.");
}
input = Console.ReadLine();
public static ManualResetEvent evtToWait = new ManualResetEvent(false);
private static void ReadDataFromConsole( object state )
{
Console.WriteLine("Enter \"x\" to exit or wait for 5 seconds.");
while (Console.ReadKey().KeyChar != 'x')
{
Console.Out.WriteLine("");
Console.Out.WriteLine("Enter again!");
}
evtToWait.Set();
}
static void Main(string[] args)
{
Thread status = new Thread(ReadDataFromConsole);
status.Start();
evtToWait = new ManualResetEvent(false);
evtToWait.WaitOne(5000); // wait for evtToWait.Set() or timeOut
status.Abort(); // exit anyway
return;
}
// Wait for 'Enter' to be pressed or 5 seconds to elapse
using (Stream s = Console.OpenStandardInput())
{
ManualResetEvent stop_waiting = new ManualResetEvent(false);
s.BeginRead(new Byte[1], 0, 1, ar => stop_waiting.Set(), null);
// ...do anything else, or simply...
stop_waiting.WaitOne(5000);
// If desired, other threads could also set 'stop_waiting'
// Disposing the stream cancels the async read operation. It can be
// re-opened if needed.
}
string readline = "?";
ThreadPool.QueueUserWorkItem(
delegate
{
readline = Console.ReadLine();
}
);
do
{
Thread.Sleep(100);
} while (readline == "?");
ConsoleKeyInfo k = new ConsoleKeyInfo();
Console.WriteLine("Press any key in the next 5 seconds.");
for (int cnt = 5; cnt > 0; cnt--)
{
if (Console.KeyAvailable)
{
k = Console.ReadKey();
break;
}
else
{
Console.WriteLine(cnt.ToString());
System.Threading.Thread.Sleep(1000);
}
}
Console.WriteLine("The key pressed was " + k.Key);
InputSimulator.SimulateKeyPress(VirtualKeyCode.RETURN);
if (SpinWait.SpinUntil(() => Console.KeyAvailable, millisecondsTimeout))
{
ConsoleKeyInfo keyInfo = Console.ReadKey();
// Handle keyInfo value here...
}
public static void Main() {
bool readInProgress = false;
System.IAsyncResult result = null;
var stop_waiting = new System.Threading.ManualResetEvent(false);
byte[] buffer = new byte[256];
var s = System.Console.OpenStandardInput();
while (true) {
if (!readInProgress) {
readInProgress = true;
result = s.BeginRead(buffer, 0, buffer.Length
, ar => stop_waiting.Set(), null);
}
bool signaled = true;
if (!result.IsCompleted) {
stop_waiting.Reset();
signaled = stop_waiting.WaitOne(5000);
}
else {
signaled = true;
}
if (signaled) {
readInProgress = false;
int numBytes = s.EndRead(result);
string text = System.Text.Encoding.UTF8.GetString(buffer
, 0, numBytes);
System.Console.Out.Write(string.Format(
"Thank you for typing: {0}", text));
}
else {
System.Console.Out.WriteLine("oy, type something!");
}
}
ConsoleKeyInfo keyInfo;
bool keyPressed = AsyncConsole.ReadKey(500, out keyInfo);
// where 500 is the timeout
public class AsyncConsole // not thread safe
{
private static readonly Lazy<AsyncConsole> Instance =
new Lazy<AsyncConsole>();
private bool _keyPressed;
private ConsoleKeyInfo _keyInfo;
private bool DoReadKey(
int millisecondsTimeout,
out ConsoleKeyInfo keyInfo)
{
_keyPressed = false;
_keyInfo = new ConsoleKeyInfo();
Thread readKeyThread = new Thread(ReadKeyThread);
readKeyThread.IsBackground = false;
readKeyThread.Start();
Thread.Sleep(millisecondsTimeout);
if (readKeyThread.IsAlive)
{
try
{
IntPtr stdin = GetStdHandle(StdHandle.StdIn);
CloseHandle(stdin);
readKeyThread.Join();
}
catch { }
}
readKeyThread = null;
keyInfo = _keyInfo;
return _keyPressed;
}
private void ReadKeyThread()
{
try
{
_keyInfo = Console.ReadKey();
_keyPressed = true;
}
catch (InvalidOperationException) { }
}
public static bool ReadKey(
int millisecondsTimeout,
out ConsoleKeyInfo keyInfo)
{
return Instance.Value.DoReadKey(millisecondsTimeout, out keyInfo);
}
private enum StdHandle { StdIn = -10, StdOut = -11, StdErr = -12 };
[DllImport("kernel32.dll")]
private static extern IntPtr GetStdHandle(StdHandle std);
[DllImport("kernel32.dll")]
private static extern bool CloseHandle(IntPtr hdl);
}
class Reader {
private static Thread inputThread;
private static AutoResetEvent getInput, gotInput;
private static string input;
static Reader() {
getInput = new AutoResetEvent(false);
gotInput = new AutoResetEvent(false);
inputThread = new Thread(reader);
inputThread.IsBackground = true;
inputThread.Start();
}
private static void reader() {
while (true) {
getInput.WaitOne();
input = Console.ReadLine();
gotInput.Set();
}
}
// omit the parameter to read a line without a timeout
public static string ReadLine(int timeOutMillisecs = Timeout.Infinite) {
getInput.Set();
bool success = gotInput.WaitOne(timeOutMillisecs);
if (success)
return input;
else
throw new TimeoutException("User did not provide input within the timelimit.");
}
}
try {
Console.WriteLine("Please enter your name within the next 5 seconds.");
string name = Reader.ReadLine(5000);
Console.WriteLine("Hello, {0}!", name);
} catch (TimeoutException) {
Console.WriteLine("Sorry, you waited too long.");
}
public static bool TryReadLine(out string line, int timeOutMillisecs = Timeout.Infinite) {
getInput.Set();
bool success = gotInput.WaitOne(timeOutMillisecs);
if (success)
line = input;
else
line = null;
return success;
}
Console.WriteLine("Please enter your name within the next 5 seconds.");
string name;
bool success = Reader.TryReadLine(out name, 5000);
if (!success)
Console.WriteLine("Sorry, you waited too long.");
else
Console.WriteLine("Hello, {0}!", name);
public static class ConsoleEx
{
public static string ReadLine(TimeSpan timeout)
{
var cts = new CancellationTokenSource();
return ReadLine(timeout, cts.Token);
}
public static string ReadLine(TimeSpan timeout, CancellationToken cancellation)
{
string line = "";
DateTime latest = DateTime.UtcNow.Add(timeout);
do
{
cancellation.ThrowIfCancellationRequested();
if (Console.KeyAvailable)
{
ConsoleKeyInfo cki = Console.ReadKey();
if (cki.Key == ConsoleKey.Enter)
{
return line;
}
else
{
line += cki.KeyChar;
}
}
Thread.Sleep(1);
}
while (DateTime.UtcNow < latest);
return null;
}
}
static void Main(string[] args)
{
Console.WriteLine("Hit q to continue or wait 10 seconds.");
Task task = Task.Factory.StartNew(() => loop());
Console.WriteLine("Started waiting");
task.Wait(10000);
Console.WriteLine("Stopped waiting");
}
static void loop()
{
while (true)
{
if ('q' == Console.ReadKey().KeyChar) break;
}
}
/// <summary>
/// Reads Line from console with timeout.
/// </summary>
/// <exception cref="System.TimeoutException">If user does not enter line in the specified time.</exception>
/// <param name="timeout">Time to wait in milliseconds. Negative value will wait forever.</param>
/// <returns></returns>
public static string ReadLine(int timeout = -1)
{
ConsoleKeyInfo cki = new ConsoleKeyInfo();
StringBuilder sb = new StringBuilder();
// if user does not want to spesify a timeout
if (timeout < 0)
return Console.ReadLine();
int counter = 0;
while (true)
{
while (Console.KeyAvailable == false)
{
counter++;
Thread.Sleep(1);
if (counter > timeout)
throw new System.TimeoutException("Line was not entered in timeout specified");
}
cki = Console.ReadKey(false);
if (cki.Key == ConsoleKey.Enter)
{
Console.WriteLine();
return sb.ToString();
}
else
sb.Append(cki.KeyChar);
}
}
Console.WriteLine("Press any key during the next 2 seconds...");
Thread.Sleep(2000);
if (Console.KeyAvailable)
{
Console.WriteLine("Key pressed");
}
else
{
Console.WriteLine("You were too slow");
}
Private Function AskUser() As String
Console.Write("Answer my question: ")
Return Console.ReadLine()
End Function
Dim askTask As Task(Of String) = New TaskFactory().StartNew(Function() AskUser())
askTask.Wait(TimeSpan.FromSeconds(30))
If Not askTask.IsCompleted Then
Console.WriteLine("User failed to respond.")
Else
Console.WriteLine(String.Format("You responded, '{0}'.", askTask.Result))
End If
var inputLine = ReadLine(5);
public static string ReadLine(uint timeoutSeconds, Func<uint, string> countDownMessage, uint samplingFrequencyMilliseconds)
{
if (timeoutSeconds == 0)
return null;
var timeoutMilliseconds = timeoutSeconds * 1000;
if (samplingFrequencyMilliseconds > timeoutMilliseconds)
throw new ArgumentException("Sampling frequency must not be greater then timeout!", "samplingFrequencyMilliseconds");
CancellationTokenSource cts = new CancellationTokenSource();
Task.Factory
.StartNew(() => SpinUserDialog(timeoutMilliseconds, countDownMessage, samplingFrequencyMilliseconds, cts.Token), cts.Token)
.ContinueWith(t => {
var hWnd = System.Diagnostics.Process.GetCurrentProcess().MainWindowHandle;
PostMessage(hWnd, 0x100, 0x0D, 9);
}, TaskContinuationOptions.NotOnCanceled);
var inputLine = Console.ReadLine();
cts.Cancel();
return inputLine;
}
private static void SpinUserDialog(uint countDownMilliseconds, Func<uint, string> countDownMessage, uint samplingFrequencyMilliseconds,
CancellationToken token)
{
while (countDownMilliseconds > 0)
{
token.ThrowIfCancellationRequested();
Thread.Sleep((int)samplingFrequencyMilliseconds);
countDownMilliseconds -= countDownMilliseconds > samplingFrequencyMilliseconds
? samplingFrequencyMilliseconds
: countDownMilliseconds;
}
}
[DllImport("User32.Dll", EntryPoint = "PostMessageA")]
private static extern bool PostMessage(IntPtr hWnd, uint msg, int wParam, int lParam);
var task = Task.Factory.StartNew(Console.ReadLine);
var result = Task.WaitAny(new Task[] { task }, TimeSpan.FromSeconds(5)) == 0
? task.Result : string.Empty;
var task = Task.Factory.StartNew(Console.ReadLine);
var completedTask = await Task.WhenAny(task, Task.Delay(TimeSpan.FromSeconds(5)));
var result = object.ReferenceEquals(task, completedTask) ? task.Result : string.Empty;
public static string ConsoleReadLineWithTimeout(TimeSpan timeout)
{
Task<string> task = Task.Factory.StartNew(Console.ReadLine);
string result = Task.WaitAny(new Task[] { task }, timeout) == 0
? task.Result
: string.Empty;
return result;
}
static void Main()
{
Console.WriteLine("howdy");
string result = ConsoleReadLineWithTimeout(TimeSpan.FromSeconds(8.5));
Console.WriteLine("bye");
}
class Program
{
static void Main(string[] args)
{
Console.WriteLine("What is the answer? (5 secs.)");
try
{
var answer = ConsoleReadLine.ReadLine(5000);
Console.WriteLine("Answer is: {0}", answer);
}
catch
{
Console.WriteLine("No answer");
}
Console.ReadKey();
}
}
class ConsoleReadLine
{
private static string inputLast;
private static Thread inputThread = new Thread(inputThreadAction) { IsBackground = true };
private static AutoResetEvent inputGet = new AutoResetEvent(false);
private static AutoResetEvent inputGot = new AutoResetEvent(false);
static ConsoleReadLine()
{
inputThread.Start();
}
private static void inputThreadAction()
{
while (true)
{
inputGet.WaitOne();
inputLast = Console.ReadLine();
inputGot.Set();
}
}
// omit the parameter to read a line without a timeout
public static string ReadLine(int timeout = Timeout.Infinite)
{
if (timeout == Timeout.Infinite)
{
return Console.ReadLine();
}
else
{
var stopwatch = new Stopwatch();
stopwatch.Start();
while (stopwatch.ElapsedMilliseconds < timeout && !Console.KeyAvailable) ;
if (Console.KeyAvailable)
{
inputGet.Set();
inputGot.WaitOne();
return inputLast;
}
else
{
throw new TimeoutException("User did not provide input within the timelimit.");
}
}
}
}