是否有办法从用户输入中读取单个字符?例如，他们在终端上按下一个键，它就会返回(有点像getch())。我知道Windows中有这个功能，但我想要跨平台的东西。
当前回答
这可能是上下文管理器的一个用例。不考虑Windows操作系统，以下是我的建议:
#!/usr/bin/env python3
# file: 'readchar.py'
"""
Implementation of a way to get a single character of input
without waiting for the user to hit <Enter>.
(OS is Linux, Ubuntu 14.04)
"""
import tty, sys, termios
class ReadChar():
def __enter__(self):
self.fd = sys.stdin.fileno()
self.old_settings = termios.tcgetattr(self.fd)
tty.setraw(sys.stdin.fileno())
return sys.stdin.read(1)
def __exit__(self, type, value, traceback):
termios.tcsetattr(self.fd, termios.TCSADRAIN, self.old_settings)
def test():
while True:
with ReadChar() as rc:
char = rc
if ord(char) <= 32:
print("You entered character with ordinal {}."\
.format(ord(char)))
else:
print("You entered character '{}'."\
.format(char))
if char in "^C^D":
sys.exit()
if __name__ == "__main__":
test()
其他回答
下面是ActiveState Recipes网站的链接，告诉你如何在Windows、Linux和OSX中读取单个字符:
getch()-类似于在Windows和Unix上从stdin读取的非缓冲字符
class _Getch:
"""Gets a single character from standard input. Does not echo to the
screen."""
def __init__(self):
try:
self.impl = _GetchWindows()
except ImportError:
self.impl = _GetchUnix()
def __call__(self): return self.impl()
class _GetchUnix:
def __init__(self):
import tty, sys
def __call__(self):
import sys, tty, termios
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(sys.stdin.fileno())
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
class _GetchWindows:
def __init__(self):
import msvcrt
def __call__(self):
import msvcrt
return msvcrt.getch()
getch = _Getch()
你可以用click。它经过了良好的测试，可以在Linux, Mac和Windows上运行。
import click
print('Continue? [yn] ')
c = click.getchar() # Gets a single character
if c == 'y':
print('We will go on')
elif c == 'n':
print('Abort!')
else:
print('Invalid input :(')
python中的curses包可以使用一些语句从终端进入“原始”模式进行字符输入。Curses的主要用途是接管屏幕进行输出，这可能不是你想要的。此代码片段使用print()语句代替，这是可用的，但必须注意curses如何更改附加到输出的行结束符。
#!/usr/bin/python3
# Demo of single char terminal input in raw mode with the curses package.
import sys, curses
def run_one_char(dummy):
'Run until a carriage return is entered'
char = ' '
print('Welcome to curses', flush=True)
while ord(char) != 13:
char = one_char()
def one_char():
'Read one character from the keyboard'
print('\r? ', flush= True, end = '')
## A blocking single char read in raw mode.
char = sys.stdin.read(1)
print('You entered %s\r' % char)
return char
## Must init curses before calling any functions
curses.initscr()
## To make sure the terminal returns to its initial settings,
## and to set raw mode and guarantee cleanup on exit.
curses.wrapper(run_one_char)
print('Curses be gone!')
这里的答案是有信息的，但是我也想要一种方法，以线程安全、跨平台的方式异步地获得按键，并在不同的事件中触发按键。PyGame对我来说也太臃肿了。所以我做了下面的代码(Python 2.7，但我怀疑它很容易移植)，我想在这里分享一下，以防对其他人有用。我将它存储在一个名为keyPress.py的文件中。
class _Getch:
"""Gets a single character from standard input. Does not echo to the
screen. From http://code.activestate.com/recipes/134892/"""
def __init__(self):
try:
self.impl = _GetchWindows()
except ImportError:
try:
self.impl = _GetchMacCarbon()
except(AttributeError, ImportError):
self.impl = _GetchUnix()
def __call__(self): return self.impl()
class _GetchUnix:
def __init__(self):
import tty, sys, termios # import termios now or else you'll get the Unix version on the Mac
def __call__(self):
import sys, tty, termios
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(sys.stdin.fileno())
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
class _GetchWindows:
def __init__(self):
import msvcrt
def __call__(self):
import msvcrt
return msvcrt.getch()
class _GetchMacCarbon:
"""
A function which returns the current ASCII key that is down;
if no ASCII key is down, the null string is returned. The
page http://www.mactech.com/macintosh-c/chap02-1.html was
very helpful in figuring out how to do this.
"""
def __init__(self):
import Carbon
Carbon.Evt #see if it has this (in Unix, it doesn't)
def __call__(self):
import Carbon
if Carbon.Evt.EventAvail(0x0008)[0]==0: # 0x0008 is the keyDownMask
return ''
else:
#
# The event contains the following info:
# (what,msg,when,where,mod)=Carbon.Evt.GetNextEvent(0x0008)[1]
#
# The message (msg) contains the ASCII char which is
# extracted with the 0x000000FF charCodeMask; this
# number is converted to an ASCII character with chr() and
# returned
#
(what,msg,when,where,mod)=Carbon.Evt.GetNextEvent(0x0008)[1]
return chr(msg & 0x000000FF)
import threading
# From https://stackoverflow.com/a/2022629/2924421
class Event(list):
def __call__(self, *args, **kwargs):
for f in self:
f(*args, **kwargs)
def __repr__(self):
return "Event(%s)" % list.__repr__(self)
def getKey():
inkey = _Getch()
import sys
for i in xrange(sys.maxint):
k=inkey()
if k<>'':break
return k
class KeyCallbackFunction():
callbackParam = None
actualFunction = None
def __init__(self, actualFunction, callbackParam):
self.actualFunction = actualFunction
self.callbackParam = callbackParam
def doCallback(self, inputKey):
if not self.actualFunction is None:
if self.callbackParam is None:
callbackFunctionThread = threading.Thread(target=self.actualFunction, args=(inputKey,))
else:
callbackFunctionThread = threading.Thread(target=self.actualFunction, args=(inputKey,self.callbackParam))
callbackFunctionThread.daemon = True
callbackFunctionThread.start()
class KeyCapture():
gotKeyLock = threading.Lock()
gotKeys = []
gotKeyEvent = threading.Event()
keyBlockingSetKeyLock = threading.Lock()
addingEventsLock = threading.Lock()
keyReceiveEvents = Event()
keysGotLock = threading.Lock()
keysGot = []
keyBlockingKeyLockLossy = threading.Lock()
keyBlockingKeyLossy = None
keyBlockingEventLossy = threading.Event()
keysBlockingGotLock = threading.Lock()
keysBlockingGot = []
keyBlockingGotEvent = threading.Event()
wantToStopLock = threading.Lock()
wantToStop = False
stoppedLock = threading.Lock()
stopped = True
isRunningEvent = False
getKeyThread = None
keyFunction = None
keyArgs = None
# Begin capturing keys. A seperate thread is launched that
# captures key presses, and then these can be received via get,
# getAsync, and adding an event via addEvent. Note that this
# will prevent the system to accept keys as normal (say, if
# you are in a python shell) because it overrides that key
# capturing behavior.
# If you start capture when it's already been started, a
# InterruptedError("Keys are still being captured")
# will be thrown
# Note that get(), getAsync() and events are independent, so if a key is pressed:
#
# 1: Any calls to get() that are waiting, with lossy on, will return
# that key
# 2: It will be stored in the queue of get keys, so that get() with lossy
# off will return the oldest key pressed not returned by get() yet.
# 3: All events will be fired with that key as their input
# 4: It will be stored in the list of getAsync() keys, where that list
# will be returned and set to empty list on the next call to getAsync().
# get() call with it, aand add it to the getAsync() list.
def startCapture(self, keyFunction=None, args=None):
# Make sure we aren't already capturing keys
self.stoppedLock.acquire()
if not self.stopped:
self.stoppedLock.release()
raise InterruptedError("Keys are still being captured")
return
self.stopped = False
self.stoppedLock.release()
# If we have captured before, we need to allow the get() calls to actually
# wait for key presses now by clearing the event
if self.keyBlockingEventLossy.is_set():
self.keyBlockingEventLossy.clear()
# Have one function that we call every time a key is captured, intended for stopping capture
# as desired
self.keyFunction = keyFunction
self.keyArgs = args
# Begin capturing keys (in a seperate thread)
self.getKeyThread = threading.Thread(target=self._threadProcessKeyPresses)
self.getKeyThread.daemon = True
self.getKeyThread.start()
# Process key captures (in a seperate thread)
self.getKeyThread = threading.Thread(target=self._threadStoreKeyPresses)
self.getKeyThread.daemon = True
self.getKeyThread.start()
def capturing(self):
self.stoppedLock.acquire()
isCapturing = not self.stopped
self.stoppedLock.release()
return isCapturing
# Stops the thread that is capturing keys on the first opporunity
# has to do so. It usually can't stop immediately because getting a key
# is a blocking process, so this will probably stop capturing after the
# next key is pressed.
#
# However, Sometimes if you call stopCapture it will stop before starting capturing the
# next key, due to multithreading race conditions. So if you want to stop capturing
# reliably, call stopCapture in a function added via addEvent. Then you are
# guaranteed that capturing will stop immediately after the rest of the callback
# functions are called (before starting to capture the next key).
def stopCapture(self):
self.wantToStopLock.acquire()
self.wantToStop = True
self.wantToStopLock.release()
# Takes in a function that will be called every time a key is pressed (with that
# key passed in as the first paramater in that function)
def addEvent(self, keyPressEventFunction, args=None):
self.addingEventsLock.acquire()
callbackHolder = KeyCallbackFunction(keyPressEventFunction, args)
self.keyReceiveEvents.append(callbackHolder.doCallback)
self.addingEventsLock.release()
def clearEvents(self):
self.addingEventsLock.acquire()
self.keyReceiveEvents = Event()
self.addingEventsLock.release()
# Gets a key captured by this KeyCapture, blocking until a key is pressed.
# There is an optional lossy paramater:
# If True all keys before this call are ignored, and the next pressed key
# will be returned.
# If False this will return the oldest key captured that hasn't
# been returned by get yet. False is the default.
def get(self, lossy=False):
if lossy:
# Wait for the next key to be pressed
self.keyBlockingEventLossy.wait()
self.keyBlockingKeyLockLossy.acquire()
keyReceived = self.keyBlockingKeyLossy
self.keyBlockingKeyLockLossy.release()
return keyReceived
else:
while True:
# Wait until a key is pressed
self.keyBlockingGotEvent.wait()
# Get the key pressed
readKey = None
self.keysBlockingGotLock.acquire()
# Get a key if it exists
if len(self.keysBlockingGot) != 0:
readKey = self.keysBlockingGot.pop(0)
# If we got the last one, tell us to wait
if len(self.keysBlockingGot) == 0:
self.keyBlockingGotEvent.clear()
self.keysBlockingGotLock.release()
# Process the key (if it actually exists)
if not readKey is None:
return readKey
# Exit if we are stopping
self.wantToStopLock.acquire()
if self.wantToStop:
self.wantToStopLock.release()
return None
self.wantToStopLock.release()
def clearGetList(self):
self.keysBlockingGotLock.acquire()
self.keysBlockingGot = []
self.keysBlockingGotLock.release()
# Gets a list of all keys pressed since the last call to getAsync, in order
# from first pressed, second pressed, .., most recent pressed
def getAsync(self):
self.keysGotLock.acquire();
keysPressedList = list(self.keysGot)
self.keysGot = []
self.keysGotLock.release()
return keysPressedList
def clearAsyncList(self):
self.keysGotLock.acquire();
self.keysGot = []
self.keysGotLock.release();
def _processKey(self, readKey):
# Append to list for GetKeyAsync
self.keysGotLock.acquire()
self.keysGot.append(readKey)
self.keysGotLock.release()
# Call lossy blocking key events
self.keyBlockingKeyLockLossy.acquire()
self.keyBlockingKeyLossy = readKey
self.keyBlockingEventLossy.set()
self.keyBlockingEventLossy.clear()
self.keyBlockingKeyLockLossy.release()
# Call non-lossy blocking key events
self.keysBlockingGotLock.acquire()
self.keysBlockingGot.append(readKey)
if len(self.keysBlockingGot) == 1:
self.keyBlockingGotEvent.set()
self.keysBlockingGotLock.release()
# Call events added by AddEvent
self.addingEventsLock.acquire()
self.keyReceiveEvents(readKey)
self.addingEventsLock.release()
def _threadProcessKeyPresses(self):
while True:
# Wait until a key is pressed
self.gotKeyEvent.wait()
# Get the key pressed
readKey = None
self.gotKeyLock.acquire()
# Get a key if it exists
if len(self.gotKeys) != 0:
readKey = self.gotKeys.pop(0)
# If we got the last one, tell us to wait
if len(self.gotKeys) == 0:
self.gotKeyEvent.clear()
self.gotKeyLock.release()
# Process the key (if it actually exists)
if not readKey is None:
self._processKey(readKey)
# Exit if we are stopping
self.wantToStopLock.acquire()
if self.wantToStop:
self.wantToStopLock.release()
break
self.wantToStopLock.release()
def _threadStoreKeyPresses(self):
while True:
# Get a key
readKey = getKey()
# Run the potential shut down function
if not self.keyFunction is None:
self.keyFunction(readKey, self.keyArgs)
# Add the key to the list of pressed keys
self.gotKeyLock.acquire()
self.gotKeys.append(readKey)
if len(self.gotKeys) == 1:
self.gotKeyEvent.set()
self.gotKeyLock.release()
# Exit if we are stopping
self.wantToStopLock.acquire()
if self.wantToStop:
self.wantToStopLock.release()
self.gotKeyEvent.set()
break
self.wantToStopLock.release()
# If we have reached here we stopped capturing
# All we need to do to clean up is ensure that
# all the calls to .get() now return None.
# To ensure no calls are stuck never returning,
# we will leave the event set so any tasks waiting
# for it immediately exit. This will be unset upon
# starting key capturing again.
self.stoppedLock.acquire()
# We also need to set this to True so we can start up
# capturing again.
self.stopped = True
self.stopped = True
self.keyBlockingKeyLockLossy.acquire()
self.keyBlockingKeyLossy = None
self.keyBlockingEventLossy.set()
self.keyBlockingKeyLockLossy.release()
self.keysBlockingGotLock.acquire()
self.keyBlockingGotEvent.set()
self.keysBlockingGotLock.release()
self.stoppedLock.release()
其思想是，您可以简单地调用keyPress.getKey()，它将从键盘读取一个键，然后返回它。
如果你想要更多的东西，我做了一个KeyCapture对象。你可以通过keys = keyPress.KeyCapture()来创建一个。
那么你可以做三件事:
addEvent(functionName)接受任何接受一个形参的函数。然后每次按下一个键时，这个函数将以该键的字符串作为输入调用。这些是在一个单独的线程中运行的，所以你可以阻止所有你想要的，它不会打乱keycapture的功能，也不会延迟其他事件。
get() returns a key in the same blocking way as before. It is now needed here because the keys are being captured via the KeyCapture object now, so keyPress.getKey() would conflict with that behavior and both of them would miss some keys since only one key can be captured at a time. Also, say the user presses 'a', then 'b', you call get(), the user presses 'c'. That get() call will immediately return 'a', then if you call it again it will return 'b', then 'c'. If you call it again it will block until another key is pressed. This ensures that you don't miss any keys, in a blocking way if desired. So in this way it's a little different than keyPress.getKey() from before
如果想要返回getKey()的行为，get(lossy=True)与get()类似，只是它只返回调用get()后按下的键。所以在上面的例子中，get()会阻塞，直到用户按下“c”，然后如果你再次调用它，它会阻塞，直到按下另一个键。
getAsync()略有不同。它的设计是为了进行大量的处理，然后偶尔返回并检查哪些键被按下。因此，getAsync()返回自上次调用getAsync()以来按下的所有键的列表，按从最早按下的键到最近按下的键的顺序排列。它也不会阻塞，这意味着如果自上次调用getAsync()以来没有按下任何键，则返回空的[]。
要真正开始捕捉键，需要使用上面创建的键对象调用keys. startcapture()。startCapture是非阻塞的，它只是启动一个只记录按键的线程，并启动另一个线程来处理这些按键。有两个线程来确保记录按键的线程不会漏掉任何按键。
如果你想停止捕获键，你可以调用keys. stopcapture()，它就会停止捕获键。但是，由于捕获键是一个阻塞操作，捕获键的线程在调用stopCapture()之后可能会捕获更多的键。
为了防止这种情况，你可以在函数的startCapture(functionName, args)中传入一个可选参数，该函数只是做一些类似检查键是否等于'c'然后退出的事情。重要的是，这个函数之前做的很少，例如，这里的sleep会导致我们错过键。
但是，如果在这个函数中调用了stopCapture()，则按键捕获将立即停止，不再尝试捕获任何按键，并且所有get()调用将立即返回，如果尚未按下任何按键则返回None。
此外，由于get()和getAsync()存储所有先前按下的键(直到检索到它们)，您可以调用clearGetList()和clearAsyncList()来忘记先前按下的键。
注意get()， getAsync()和事件是独立的，所以如果按下一个键:
对正在等待的get()的调用，如果打开了lossy，就会返回 的关键。其他正在等待的呼叫(如果有)将继续等待。 该键将存储在get键队列中，因此带有lossy off的get()将返回get()尚未返回的按下的最古老的键。 所有事件都将以该键作为输入触发 该键将存储在getAsync()键的列表中，该列表将在下一次调用getAsync()时返回并设置为空列表
如果所有这些都太多了，这里有一个示例用例:
import keyPress
import time
import threading
def KeyPressed(k, printLock):
printLock.acquire()
print "Event: " + k
printLock.release()
time.sleep(4)
printLock.acquire()
print "Event after delay: " + k
printLock.release()
def GetKeyBlocking(keys, printLock):
while keys.capturing():
keyReceived = keys.get()
time.sleep(1)
printLock.acquire()
if not keyReceived is None:
print "Block " + keyReceived
else:
print "Block None"
printLock.release()
def GetKeyBlockingLossy(keys, printLock):
while keys.capturing():
keyReceived = keys.get(lossy=True)
time.sleep(1)
printLock.acquire()
if not keyReceived is None:
print "Lossy: " + keyReceived
else:
print "Lossy: None"
printLock.release()
def CheckToClose(k, (keys, printLock)):
printLock.acquire()
print "Close: " + k
printLock.release()
if k == "c":
keys.stopCapture()
printLock = threading.Lock()
print "Press a key:"
print "You pressed: " + keyPress.getKey()
print ""
keys = keyPress.KeyCapture()
keys.addEvent(KeyPressed, printLock)
print "Starting capture"
keys.startCapture(CheckToClose, (keys, printLock))
getKeyBlockingThread = threading.Thread(target=GetKeyBlocking, args=(keys, printLock))
getKeyBlockingThread.daemon = True
getKeyBlockingThread.start()
getKeyBlockingThreadLossy = threading.Thread(target=GetKeyBlockingLossy, args=(keys, printLock))
getKeyBlockingThreadLossy.daemon = True
getKeyBlockingThreadLossy.start()
while keys.capturing():
keysPressed = keys.getAsync()
printLock.acquire()
if keysPressed != []:
print "Async: " + str(keysPressed)
printLock.release()
time.sleep(1)
print "done capturing"
从我做的简单测试来看，它对我来说工作得很好，但如果我遗漏了什么，我也会很高兴地接受其他人的反馈。
我也把这个贴在这里了。
这可能是上下文管理器的一个用例。不考虑Windows操作系统，以下是我的建议:
#!/usr/bin/env python3
# file: 'readchar.py'
"""
Implementation of a way to get a single character of input
without waiting for the user to hit <Enter>.
(OS is Linux, Ubuntu 14.04)
"""
import tty, sys, termios
class ReadChar():
def __enter__(self):
self.fd = sys.stdin.fileno()
self.old_settings = termios.tcgetattr(self.fd)
tty.setraw(sys.stdin.fileno())
return sys.stdin.read(1)
def __exit__(self, type, value, traceback):
termios.tcsetattr(self.fd, termios.TCSADRAIN, self.old_settings)
def test():
while True:
with ReadChar() as rc:
char = rc
if ord(char) <= 32:
print("You entered character with ordinal {}."\
.format(ord(char)))
else:
print("You entered character '{}'."\
.format(char))
if char in "^C^D":
sys.exit()
if __name__ == "__main__":
test()
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