Python用tkinter发送websocket消息

Question

我在python 2.7上的tkinter中发送websocket消息时遇到麻烦。我目前有tkinter和websocket客户端在一个线程中运行，所以它们两个循环同时工作，如下图所示。问题是，每当我尝试键入消息并按下发送按钮时，都会得到一个NameError。我正在使用的websocket客户端在这里。

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()

当我尝试发送消息时，这是我在IDLE中得到的错误消息:

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:Python27liblib-tkTkinter.py", line 1486, in __call__
    return self.func(*args)
  File "C:UsersUserDesktopthing.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这个问题。websocket on_open函数使用ws.send()成功地将消息发送到服务器，但是sendmsg函数没有。感谢所有的帮助，因为我是一个全新的线程。

Answer 1

那是因为你有

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

看起来您稍后确实创建了一个ws实例，在connection()中，您执行ws = WebSocketApp("ws://echo.websocket.org/", on_message = on_message, on_error = on_error, on_close = on_close)。只要确保在使用ws之前完成了这一点，因为这是它被定义的地方。