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

试试这个:http://home.wlu.edu/~levys/software/kbhit.py 它是非阻塞的(这意味着您可以有一个while循环并检测按键而无需停止它)和跨平台的。

import os

# Windows
if os.name == 'nt':
    import msvcrt

# Posix (Linux, OS X)
else:
    import sys
    import termios
    import atexit
    from select import select


class KBHit:

    def __init__(self):
        '''Creates a KBHit object that you can call to do various keyboard things.'''

        if os.name == 'nt':
            pass

        else:

            # Save the terminal settings
            self.fd = sys.stdin.fileno()
            self.new_term = termios.tcgetattr(self.fd)
            self.old_term = termios.tcgetattr(self.fd)

            # New terminal setting unbuffered
            self.new_term[3] = (self.new_term[3] & ~termios.ICANON & ~termios.ECHO)
            termios.tcsetattr(self.fd, termios.TCSAFLUSH, self.new_term)

            # Support normal-terminal reset at exit
            atexit.register(self.set_normal_term)


    def set_normal_term(self):
        ''' Resets to normal terminal.  On Windows this is a no-op.
        '''

        if os.name == 'nt':
            pass

        else:
            termios.tcsetattr(self.fd, termios.TCSAFLUSH, self.old_term)


    def getch(self):
        ''' Returns a keyboard character after kbhit() has been called.
            Should not be called in the same program as getarrow().
        '''

        s = ''

        if os.name == 'nt':
            return msvcrt.getch().decode('utf-8')

        else:
            return sys.stdin.read(1)


    def getarrow(self):
        ''' Returns an arrow-key code after kbhit() has been called. Codes are
        0 : up
        1 : right
        2 : down
        3 : left
        Should not be called in the same program as getch().
        '''

        if os.name == 'nt':
            msvcrt.getch() # skip 0xE0
            c = msvcrt.getch()
            vals = [72, 77, 80, 75]

        else:
            c = sys.stdin.read(3)[2]
            vals = [65, 67, 66, 68]

        return vals.index(ord(c.decode('utf-8')))


    def kbhit(self):
        ''' Returns True if keyboard character was hit, False otherwise.
        '''
        if os.name == 'nt':
            return msvcrt.kbhit()

        else:
            dr,dw,de = select([sys.stdin], [], [], 0)
            return dr != []

使用这个的例子:

import kbhit

kb = kbhit.KBHit()

while(True): 
    print("Key not pressed") #Do something
    if kb.kbhit(): #If a key is pressed:
        k_in = kb.getch() #Detect what key was pressed
        print("You pressed ", k_in, "!") #Do something
kb.set_normal_term()

或者您可以使用PyPi中的getch模块。但是这会阻塞while循环

其他回答

这是NON-BLOCKING,读取一个键并将其存储在keypress.key中。

import Tkinter as tk


class Keypress:
    def __init__(self):
        self.root = tk.Tk()
        self.root.geometry('300x200')
        self.root.bind('<KeyPress>', self.onKeyPress)

    def onKeyPress(self, event):
        self.key = event.char

    def __eq__(self, other):
        return self.key == other

    def __str__(self):
        return self.key

在你的程序中

keypress = Keypress()

while something:
   do something
   if keypress == 'c':
        break
   elif keypress == 'i': 
       print('info')
   else:
       print("i dont understand %s" % keypress)

另一种方法:

import os
import sys    
import termios
import fcntl

def getch():
  fd = sys.stdin.fileno()

  oldterm = termios.tcgetattr(fd)
  newattr = termios.tcgetattr(fd)
  newattr[3] = newattr[3] & ~termios.ICANON & ~termios.ECHO
  termios.tcsetattr(fd, termios.TCSANOW, newattr)

  oldflags = fcntl.fcntl(fd, fcntl.F_GETFL)
  fcntl.fcntl(fd, fcntl.F_SETFL, oldflags | os.O_NONBLOCK)

  try:        
    while 1:            
      try:
        c = sys.stdin.read(1)
        break
      except IOError: pass
  finally:
    termios.tcsetattr(fd, termios.TCSAFLUSH, oldterm)
    fcntl.fcntl(fd, fcntl.F_SETFL, oldflags)
  return c

摘自这篇博文。

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!')

这里回答:python中的raw_input,不按enter

使用这个代码-

from tkinter import Tk, Frame


def __set_key(e, root):
    """
    e - event with attribute 'char', the released key
    """
    global key_pressed
    if e.char:
        key_pressed = e.char
        root.destroy()


def get_key(msg="Press any key ...", time_to_sleep=3):
    """
    msg - set to empty string if you don't want to print anything
    time_to_sleep - default 3 seconds
    """
    global key_pressed
    if msg:
        print(msg)
    key_pressed = None
    root = Tk()
    root.overrideredirect(True)
    frame = Frame(root, width=0, height=0)
    frame.bind("<KeyRelease>", lambda f: __set_key(f, root))
    frame.pack()
    root.focus_set()
    frame.focus_set()
    frame.focus_force()  # doesn't work in a while loop without it
    root.after(time_to_sleep * 1000, func=root.destroy)
    root.mainloop()
    root = None  # just in case
    return key_pressed


def __main():
        c = None
        while not c:
                c = get_key("Choose your weapon ... ", 2)
        print(c)

if __name__ == "__main__":
    __main()

参考:https://github.com/unfor19/mg-tools/blob/master/mgtools/get_key_pressed.py

另一个回答中的一个评论提到了cbreak模式,这对Unix实现很重要,因为您通常不希望^C (KeyboardError)被getchar使用(当您将终端设置为原始模式时,它会被使用,就像大多数其他回答所做的那样)。

另一个重要的细节是,如果您希望读取一个字符而不是一个字节,您应该从输入流中读取4个字节,因为这是UTF-8 (Python 3+)中单个字符所包含的最大字节数。对于键盘箭头等多字节字符,只读取一个字节将产生意想不到的结果。

下面是我修改后的Unix实现:

import contextlib
import os
import sys
import termios
import tty


_MAX_CHARACTER_BYTE_LENGTH = 4


@contextlib.contextmanager
def _tty_reset(file_descriptor):
    """
    A context manager that saves the tty flags of a file descriptor upon
    entering and restores them upon exiting.
    """
    old_settings = termios.tcgetattr(file_descriptor)
    try:
        yield
    finally:
        termios.tcsetattr(file_descriptor, termios.TCSADRAIN, old_settings)


def get_character(file=sys.stdin):
    """
    Read a single character from the given input stream (defaults to sys.stdin).
    """
    file_descriptor = file.fileno()
    with _tty_reset(file_descriptor):
        tty.setcbreak(file_descriptor)
        return os.read(file_descriptor, _MAX_CHARACTER_BYTE_LENGTH)