使用 Pyqt4 从 URL 下载数千个 PDF

理想情况下，我试图从给定网站下载数千个 PDF。然而，由于某种原因，它甚至无法下载 100 个 PDF。我不知道为什么。这是代码：

#!/usr/bin/env python
import time
from pyPdf import PdfFileWriter, PdfFileReader
import StringIO
from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import letter
from xhtml2pdf import pisa
import sys 
from PyQt4.QtCore import *
from PyQt4.QtGui import*
from PyQt4.QtWebKit import *

class Foo(QWidget):
    def __init__(self, parent=None):
        super(Foo, self).__init__(parent)    

        self.count  = -1
        text_file = open("input.txt", "r")
        self.params = text_file.read().split('\n')
        self.url    = 'http://www.asdfasdfasdf.com/Property.aspx?mode=details&pin={0}'

        self.gridLayout = QGridLayout(self)
        #self.tabWidget = QTabWidget(self)
        #self.gridLayout.addWidget(self.tabWidget, 0, 0, 1, 1)

        self.mapper = QSignalMapper(self)
        self.mapper.mapped.connect(self.on_mapper_mapped)

        for i in range(100):
            grabber = QWebView()
            grabber.loadFinished.connect(self.mapper.map)

            self.mapper.setMapping(grabber, i)
            #self.tabWidget.addTab(grabber, "opener {0}".format(str(i)))

            grabber.loadFinished.emit(True)

    @pyqtSlot(int)
    def on_mapper_mapped(self, gNumber):
        self.count += 1
        if self.count < len(self.params):
            #gParam = self.params[self.count]
            gParam = self.params[self.count]

            opener = self.mapper.mapping(gNumber)
            opener.load(QUrl(self.url.format(gParam)))
            printer = QPrinter()
            #setting format
            printer.setPageSize(QPrinter.A4)
            printer.setOutputFormat(QPrinter.PdfFormat)
            #export file as c:\tem_pdf.pdf
            PIDString = gParam[:2] + '-' + gParam[2:4] + '-' + gParam[4:7] + '-' + gParam[7:10] + '-' + gParam[10:14]
            printer.setOutputFileName(PIDString + '.pdf')
            def convertIt():
                opener.print_(printer)

            QObject.connect(opener, SIGNAL("loadFinished(bool)"), convertIt)
            print str(self.count) + ' of ' + str(len(self.params))



if __name__ == "__main__":
    import  sys

    app = QApplication(sys.argv)
    main = Foo()
    #main.show()
    app.exec_()
    sys.exit

理想情况下，我也想添加页脚，但如果我尝试这样做，它就会出错。 Input.txt 有 100 个数字（仅用于测试，我需要它在 85000 上工作）。它适用于真正的小数字，例如 5 或 10，但不适用于 100。 QwebView 实例有限制吗？我应该管理它才能使其发挥作用吗？

当我为 100 个 PDF 运行此代码时，它将打印出 20 个 PDF。如果我将范围更改为小于 100，则会有重复的 PDF，但肯定会超过 20。

另外，我收到此错误：

qpainter::begin：返回 false

我认为既然您正在尝试制作“PyQt 应用程序”，您应该首先利用它提供的功能。

尝试看看Q网络访问管理器 http://doc.qt.io/qt-5/qnetworkaccessmanager.html控制您的所有请求和其他一切，Q网络请求 http://doc.qt.io/qt-5/qnetworkrequest.html, Q网络回复 http://doc.qt.io/qt-5/qnetworkreply.html.

它甚至会照顾您的线程并根据需要实现并行性。下载时不会冻结您的应用程序。

稍微看一下我的这段代码。它并不能完全满足您的要求，但对于您需要进行的所有设置来说，这是一个非常好的过滤示例。

# Subclass QNetworkAccessManager Here
from PyQt5.QtCore import QByteArray
from PyQt5.QtCore import QFile, pyqtSlot
from PyQt5.QtCore import QIODevice
from PyQt5.QtCore import QUrl
from PyQt5.QtCore import pyqtSignal
from PyQt5.QtNetwork import QNetworkAccessManager
from PyQt5.QtNetwork import QNetworkRequest


class NetworkAccessManager(QNetworkAccessManager):

    signal_add_image = pyqtSignal()
    dialog = None
    download_finished = False
    message_buffer = None
    reply = None

    def __init__(self):
        QNetworkAccessManager.__init__(self)
        self.reply = self.get(QNetworkRequest(QUrl("")))

    # Save image data in QByteArray buffer to the disk (google_image_logo.png
    # in the same directory)
    @pyqtSlot()
    def slot_finished(self):
        image_file = QFile("resources/browser_images/image_required_browser")
        if image_file.open(QIODevice.ReadWrite):
            image_file.write(self.message_buffer)
            image_file.close()
            self.signal_add_image.emit()
            # QMessageBox.information(None, "Hello!", "File has been saved!")
        else:
            pass
            # QMessageBox.critical(None, "Hello!", "Error saving file!")
        self.download_finished = True
        self.dialog.close()

    # Append current data to the buffer every time readyRead() signal is
    # emitted
    @pyqtSlot()
    def slot_read_data(self):
        self.message_buffer += self.reply.readAll()

    def request_image(self, url, progress_bar, dialog):
        self.reply.deleteLater()
        self.download_finished = False
        self.dialog = dialog
        self.message_buffer = QByteArray()
        url = QUrl(url)
        req = QNetworkRequest(url)
        req.setRawHeader(b'User-Agent',
                                    b'Mozilla/5.0 (Windows NT 6.2; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1667.0 Safari/537.36')
        self.reply = self.get(req)
        self.reply.readyRead.connect(self.slot_read_data)
        self.reply.finished.connect(self.slot_finished)
        self.reply.downloadProgress.connect(progress_bar)

    def get_reply(self):
        return self.reply

    def done(self):
        return self.download_finished

    def set_reply(self, reply):
        self.reply = reply

    def del_reply(self):
        self.reply.deleteLater()

NETWORK_ACCESS_MANAGER = NetworkAccessManager()

希望它能给你带来一些光明”）