为什么在Python中发出HTTP请求时不能查看标签的更新 [英] Why can't I view updates to a label while making an HTTP request in Python

问题描述

我有此代码:

def on_btn_login_clicked(self, widget):
    email = self.log_email.get_text()
    passw = self.log_pass.get_text()
    self.lbl_status.set_text("Connecting ...")
    params = urllib.urlencode({'@log_email': email, '@log_pass': passw, '@action': 'login', '@module': 'user'})
    headers = {"Content-type": "application/x-www-form-urlencoded","Accept": "text/plain"}
    conn = httplib.HTTPConnection("website.com")
    self.lbl_status.set_text("Logging in ...")
    conn.request("POST", "/ajax.php", params, headers)
    response = conn.getresponse()
    print response.status
    self.lbl_status.set_text("")
    data = response.read()      
    print data
    conn.close()

在请求完成之前，self.lbl_status不会更改，因此由于最后一个set_text函数而没有显示任何内容.

The self.lbl_status doesn't change till the request is finished, so it displays nothing due to the last set_text function.

为什么会这样，以及如何避免/修复该问题?

Why is this happening, and how to avoid/fix that?

推荐答案

下面是一个简单下载器的有效示例，仅用于说明目的.如果您希望GUI能够响应并在长时间运行或阻塞操作时不冻结，则需要使用多线程.我根据此堆栈溢出问题和这篇出色的文章在PyGTK中使用线程. Ubuntu iso的默认URL将花费一些时间下载，并应提供一个很好的演示.提示时，您可以输入所需的任何URL，它将下载文件并将其保存在当前目录中.

Below is a working example of a simple downloader for illustration purposes only. You need to use multi-threading if you want your GUI to be responsive and not freeze while you do some long running or blocking operation. I put this example together based on this stack overflow question and this excellent article Using threads in PyGTK. The default url an Ubuntu iso will take a while to download and should provide a good demonstration . You can enter any url you want when prompted it will download and save the file in the current directory.

from threading import Thread
import time
import gtk, gobject, urllib

URL = 'http://releases.ubuntu.com//precise/ubuntu-12.04.1-desktop-i386.iso'

def download(url):
    filename = url.split('/')[-1]
    out = open(filename, 'wb')
    gobject.idle_add(label.set_text, "connecting...")
    f = urllib.urlopen(url)
    buffer = f.read(1024)
    counter = 0
    while buffer:
        counter += len(buffer)
        out.write(buffer)
        msg = "downloaded {0:,} bytes".format(counter)
        gobject.idle_add(label.set_text, msg)
        buffer = f.read(1024)
    out.close()
    gobject.idle_add(label.set_text, "download complete")

def clicked(button):
    url = entry.get_text()
    Thread(target=download, args=(url,)).start()


gtk.gdk.threads_init()
win = gtk.Window()
win.set_default_size(400, 100)
entry = gtk.Entry()
entry.set_text(URL)
label = gtk.Label("Press the button")
button = gtk.Button(label="Download")
button.connect('clicked', clicked)

box = gtk.VBox()
box.pack_start(entry)
box.pack_start(label)
box.pack_start(button)
win.add(box)

win.show_all()

gtk.main()

这篇关于为什么在Python中发出HTTP请求时不能查看标签的更新的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！