Python在tkinter中发送websocket消息

Question

我在 python 2.7 上的 tkinter 中发送 websocket 消息时遇到问题。我目前有 tkinter 和一个 websocket 客户端在一个线程中运行，因此它们两个循环同时工作，如 here 所示。问题是，每当我尝试输入消息并按下发送按钮时，都会收到 NameError。我使用的 websocket 客户端是here。

这是我的代码：

from Tkinter import *
from websocket import *
from threading import *

master = Tk()
master.wm_title("Websocket Test")
minwidth = master.winfo_screenwidth()/4*3
minheight = master.winfo_screenheight()/4*3
master.minsize(width=minwidth, height=minheight)
master.resizable(0,0)

def sendmsg():
   msg = entry.get()
   ws.send(msg)
   return

text = Text(master)
text.pack(side=TOP, expand=True,fill=BOTH)
entry = Entry(master)
entry.pack(side=BOTTOM, expand=True, fill=BOTH)
button = Button(master, text="SEND", command=sendmsg)
button.pack(side=BOTTOM, expand=True, fill=BOTH)

def on_message(ws, message):
   text.insert(END, "Received: "+message+"\n")
   print "Received: "+message
   return

def on_error(ws, error):
   text.insert(END, error+"\n")
   print error
   return

def on_close(ws):
   text.insert(END, "### closed ###\n")
   print "### closed ###"
   return

def on_open(ws):
   ws.send("hello")
   ws.send("testing")
   return

def connection():
   enableTrace(True)
   ws = WebSocketApp("ws://echo.websocket.org/", on_message = on_message, on_error = on_error, on_close = on_close)
   ws.on_open = on_open

   ws.run_forever()
   return

t = Thread(target=connection)
t.start()

master.mainloop()

这是我在尝试发送消息时在 IDLE 中收到的错误消息：

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Python27\lib\lib-tk\Tkinter.py", line 1486, in __call__
    return self.func(*args)
  File "C:\Users\User\Desktop\thing.py", line 14, in sendmsg
    ws.send(msg)
NameError: global name 'ws' is not defined

我认为这与线程有关，但我不确定是什么导致了问题。 websocket on_open 函数使用 ws.send() 成功将消息发送到服务器，但 sendmsg 函数没有。感谢所有帮助，因为我对线程完全陌生。

Answer 1

那是因为你这样做

def sendmsg():
    msg = entry.get()
    ws.send(msg)
    return

你需要先实例化websocket：

def sendmsg():
    ws = WebSocketApp("ws://echo.websocket.org/", on_message = on_message, on_error = on_error, on_close = on_close)
    msg = entry.get()
    ws.send(msg)
    return

看起来你稍后确实创建了一个 ws 实例，在 connection() 中，你创建了 ws = WebSocketApp("ws://echo.websocket.org/", on_message = on_message, on_error = on_error, on_close = on_close)。请确保在使用 ws 之前已完成此操作，因为这是定义它的地方。