【发布时间】：2018-04-25 06:58:55
【问题描述】：
背景：
我有一个脚本，允许我通过来自私人编辑器的 API 对 PostgreSQL 数据库进行空间查询（我无法直接查询数据库）。此 API 适用于 python 3.2。快速总结一下，此脚本用于在所需的地理足迹中下载此数据库的元素。根据区域的不同，您可以获得 1 到 100 多个元素，每个元素的大小都非常不同（从 Ko 到 Go）。
主窗口让您设置所有选项，然后启动全局进程。启动时会出现一个控制台窗口，让您查看发生了什么。下载项目后，控制台上会显示一个简短的“报告”。目前，一切都是按顺序完成的，一次一个元素。可以想象，如果这个元素很大，控制台会在等待下载过程结束时冻结。
代码：
我不打算在这里发布完整的脚本，但是通过一个非常简单的脚本，我将尝试展示我正在尝试解决的主要问题（即避免锁定用户界面/具有某种实时性输出正在发生的事情）。
因此，为了避免这些冻结问题，在我看来，使用线程是最好的解决方案。为了模拟下载过程（参见上一章），我使用了带有多个 url（指向不同大小的文件）的 url.request urlretrieve 方法。
import os
import sys
import time
import urllib.request
from PyQt4 import QtCore, QtGui
url_1m = 'http://ipv4.sbg.proof.ovh.net/files/1Mio.dat'
url_10m = 'http://ipv4.sbg.proof.ovh.net/files/10Mio.dat'
url_100m = 'http://ipv4.sbg.proof.ovh.net/files/100Mio.dat'
url_1g = 'http://ipv4.sbg.proof.ovh.net/files/1Gio.dat'
url_10g = 'http://ipv4.sbg.proof.ovh.net/files/10Gio.dat'
urls = (url_1m, url_10m, url_100m, url_1g, url_10g)
# ---------------------------------------------------------------------------------
class DownloadWorkerSignals(QtCore.QObject):
"""
Defines the signals available from a running download worker thread.
"""
finished = QtCore.pyqtSignal(str)
# ---------------------------------------------------------------------------------
class DownloadWorker(QtCore.QRunnable):
"""
Worker thread
"""
def __init__(self, url, filepath, filename, index):
super(DownloadWorker, self).__init__()
self.url = url
self.file_path = filepath
self.filename = filename
self.index = index
self.signals = DownloadWorkerSignals()
@QtCore.pyqtSlot(str)
def run(self):
t = time.time()
message = 'Thread %d started\n' % self.index
try:
# The urlretrieve method will copy a network object to a local file
urllib.request.urlretrieve(url=self.url,
filename=os.path.join(self.file_path,
self.filename))
except IOError as error:
message += str(error) + '\n'
finally:
message += 'Thread %d ended %.2f s\n' % (self.index, time.time() - t)
self.signals.finished.emit(message) # Done
# ---------------------------------------------------------------------------------
class Main(QtGui.QMainWindow):
"""
Main window
"""
def __init__(self):
super(self.__class__, self).__init__()
self.resize(400, 200)
self.setWindowTitle("Main")
self.setWindowModality(QtCore.Qt.ApplicationModal)
self.centralwidget = QtGui.QWidget(self)
self.setCentralWidget(self.centralwidget)
# Ok / Close
# -------------------------------------------------------------------------
self.buttonBox = QtGui.QDialogButtonBox(self.centralwidget)
self.buttonBox.setStandardButtons(QtGui.QDialogButtonBox.Cancel |
QtGui.QDialogButtonBox.Ok)
self.buttonBox.setGeometry(QtCore.QRect(10, 160, 380, 20))
# Connect definition
# -------------------------------------------------------------------------
self.connect(self.buttonBox,
QtCore.SIGNAL('accepted()'),
self.button_ok_clicked)
self.connect(self.buttonBox,
QtCore.SIGNAL('rejected()'),
self.button_cancel_clicked)
# Connect functions
# -----------------------------------------------------------------------------
def button_cancel_clicked(self):
self.close()
def button_ok_clicked(self):
# Launch console
console = Console(parent=self)
console.exec_()
# ---------------------------------------------------------------------------------------------------------------
class Console(QtGui.QDialog):
"""
Console window
"""
def __init__(self, parent):
super(self.__class__, self).__init__()
self.parent = parent
self.resize(400, 200)
self.setWindowTitle("Console")
self.setModal(True)
self.verticalLayout = QtGui.QVBoxLayout(self)
# Text edit
# -------------------------------------------------------------------------
self.text_edit = QtGui.QPlainTextEdit(self)
self.text_edit.setReadOnly(True)
self.text_edit_cursor = QtGui.QTextCursor(self.text_edit.document())
self.verticalLayout.addWidget(self.text_edit)
# Ok / Close
# -------------------------------------------------------------------------
self.button_box = QtGui.QDialogButtonBox(self)
self.button_box.setStandardButtons(QtGui.QDialogButtonBox.Close)
self.verticalLayout.addWidget(self.button_box)
# Connect definition
# -------------------------------------------------------------------------
self.connect(self.button_box.button(QtGui.QDialogButtonBox.Close),
QtCore.SIGNAL('clicked()'),
self.button_cancel_clicked)
# Post initialization
# -------------------------------------------------------------------------
self.threadpool = QtCore.QThreadPool()
self.threadpool.setMaxThreadCount(2)
for index, url in enumerate(urls):
worker = DownloadWorker(url=url,
filepath='C:\\Users\\philippe\\Downloads',
filename='url_%d.txt' % index,
index=index)
worker.signals.finished.connect(self.write_message)
self.threadpool.start(worker)
'''
I have to wait for the end of the thread pool to make a post-processing.
If I use the waitForDone I don't see my console until the all work is done
'''
# self.threadpool.waitForDone()
# self.write_stram('Thread pool finished')
# Connect functions
# -----------------------------------------------------------------------------
def button_cancel_clicked(self):
if self.threadpool.activeThreadCount() != 0:
pass # How to interrupt the threadpool ?
self.close()
@QtCore.pyqtSlot(str)
def write_message(self, text):
self.text_edit.insertPlainText(text)
cursor = self.text_edit.textCursor()
self.text_edit.setTextCursor(cursor)
# ---------------------------------------------------------------------------------
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
window = Main()
window.show()
app.exec_()
问题：
一切似乎都按预期工作，但我遇到了两个困难：
- 在线程池进程结束时我必须做一些 后期处理。如果我使用 waitForDone 方法，我看不到我的 控制台，直到所有工作完成，这不是行为的类型 通缉。
- 如果控制台中的取消按钮被点击，我需要中断 线程池，我不知道如何管理它。
【问题讨论】：
-
找到问题 #2 的答案：stackoverflow.com/questions/20844335/…>
标签： python python-3.x pyqt pyqt4 qthread