python - 如何通过 QNetworkAccessManager 找到下载图像的确切 url

Question

我正在使用 QNetworkAccessManager 下载图像。

第一次，我必须指定图像的url。

但方式不同。

例如，我从 Wikipedia Top Page Japanese 的图像中获取.

有一些正在上传的图片。

如果我复制文本和图像，然后将它们粘贴到我的编辑器中，html 文本包含 url。

即使我将其传递到QNetworkRequest中，我也无法下载图像。

在我深入研究 URL 并找到 Wikipedia Commons 中的图像文件后,如果我将网址传递到QNetworkRequest，我就可以下载图像。

我已经知道 url 必须准确，但我不知道如何区分它们。

您知道如何每次都以编程方式下载图像而不会出错吗？

有什么办法可以提前知道确切的网址吗？

我对网络了解不多。

我经常接受UnknownContentError

示例代码使用方法

Ctrl+C 复制文本和图像(请包含图像。)Ctrl+V 粘贴 html 并下载图像

Q直接下载图片。我只能通过这个下载。

示例代码

from PySide import QtCore, QtGui, QtNetwork
from bs4 import BeautifulSoup
import sys, os, re
class Widget(QtGui.QTextEdit):
    def __init__(self, parent=None):
        super(Widget, self).__init__()   

    def keyPressEvent(self, event):
        if event.modifiers() == QtCore.Qt.KeyboardModifier.ControlModifier and event.key() == QtCore.Qt.Key_C:
            tc = self.textCursor()                       
            mimedata = self.createMimeDataFromSelection()
            clipboard = QtGui.QApplication.clipboard()
            clipboard.setMimeData(mimedata)
            start = tc.selectionStart()
            end = tc.selectionEnd()                   
            char = tc.charFormat()
            char.clearBackground()
            tc.setCharFormat(char)             
            return 
        elif event.modifiers() == QtCore.Qt.KeyboardModifier.ControlModifier and event.key() == QtCore.Qt.Key_V:
            clipboard = QtGui.QApplication.clipboard()

            html = clipboard.mimeData().html()                      
            pous = BeautifulSoup(html,"lxml")
            image_items  = pous.find_all('a', href=re.compile('(\.jpg|\.png|\.svg|\.gif)$'))
            image_urls = [item.get('href') for item in image_items]      
            for i, url in enumerate(image_urls):                    
                #indirect url  https://ja.wikipedia.org/wiki/%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB:Oguri_Cap_in_Yushun_Stallion_station.jpg
                print(url)
                request = QtNetwork.QNetworkRequest(QtCore.QUrl(url))       
                self.nam = QtNetwork.QNetworkAccessManager() 
                self.nam.finished[QtNetwork.QNetworkReply].connect(self.doReply)
                self.nam.get(request)
        if event.key() == QtCore.Qt.Key_Q:
            self.doRequest()
    def doRequest(self):        
        # direct url & exact url
        url = "https://upload.wikimedia.org/wikipedia/commons/c/c3/Oguri_Cap_in_Yushun_Stallion_station.jpg"
        req = QtNetwork.QNetworkRequest(QtCore.QUrl(url))    
        self.nam = QtNetwork.QNetworkAccessManager()     
        self.nam.finished[QtNetwork.QNetworkReply].connect(self.doReply)       
        self.nam.get(req)    
    def doReply(self, reply):
        er = reply.error()
        if er == QtNetwork.QNetworkReply.NoError:    
            data = reply.readAll()            
            self.saveImage(data)                    
        else:
            print( "Error occured: ", er)
            print(  reply.errorString())
    def saveImage(self, data):
        try:           
            im = QtGui.QImageWriter()            
            im.setFileName(os.path.join(os.getcwd(),"wiki_topimage.png"))           
            imd = QtGui.QImage()
            imd_bool = imd.loadFromData(data.data())
            im.write(imd)
        except Exception as e:
            print(e)

def main():
    QtCore.QCoreApplication.addLibraryPath(os.path.join(os.getcwd(),"plugins"))  
    try:
        QtGui.QApplication([])

    except Exception as e:
        print("error", e)
    w = Widget()
    w.show()
    sys.exit(QtGui.QApplication.exec_())
if __name__ == "__main__":
    main()

Answer 1

您有以下错误:

• 您应该使用的网址位于子 img 标记的 src 属性中。
• 您只需创建一个 QNetworkAccessManager，否则新的 QNetworkAccessManager 将消除之前的 QNetworkAccessManager。
• 您必须使用QUrl::fromUserInput()因为它处理尝试多种配置的 url，例如在本例中它可以转换 url:

https://ja.wikipedia.org/wiki/%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB:Oguri_Cap_in_Yushun_Stallion_station.jpg

至

https://ja.wikipedia.org/wiki/ファイル:Oguri_Cap_in_Yushun_Stallion_station.jpg

import os
import sys
import re
from PySide import QtCore, QtGui, QtNetwork
from bs4 import BeautifulSoup


class Widget(QtGui.QTextEdit):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent)
        self.nam = QtNetwork.QNetworkAccessManager(self)
        self.nam.finished[QtNetwork.QNetworkReply].connect(self.doReply)

    def keyPressEvent(self, event):
        if event.matches(QtGui.QKeySequence.Copy):
            tc = self.textCursor()
            mimedata = self.createMimeDataFromSelection()
            clipboard = QtGui.QApplication.clipboard()
            clipboard.setMimeData(mimedata)
            start = tc.selectionStart()
            end = tc.selectionEnd()
            char = tc.charFormat()
            char.clearBackground()
            tc.setCharFormat(char)
            return
        elif event.matches(QtGui.QKeySequence.Paste):
            clipboard = QtGui.QApplication.clipboard()

            html = clipboard.mimeData().html()
            pous = BeautifulSoup(html, "lxml")
            image_items = pous.find_all(
                "a", href=re.compile(r"(\.jpg|\.png|\.svg|\.gif)$")
            )
            for i, item in enumerate(image_items):
                url = item.find("img", recursive=False).get("src")
                print(i, url)
                request = QtNetwork.QNetworkRequest(
                    QtCore.QUrl.fromUserInput(url)
                )
                self.nam.get(request)

    @QtCore.Slot(QtNetwork.QNetworkReply)
    def doReply(self, reply):
        er = reply.error()
        if er == QtNetwork.QNetworkReply.NoError:
            print("ok", reply.url())
            name = reply.url().path().split("/")[-1]
            filename = os.path.join(os.getcwd(), name)
            file = QtCore.QFile(filename)
            if file.open(QtCore.QIODevice.WriteOnly):
                file.write(reply.readAll())
        else:
            print("Error occured: ", er, reply.url())
        reply.deleteLater()


def main():
    QtCore.QCoreApplication.addLibraryPath(os.path.join(os.getcwd(), "plugins"))
    app = QtGui.QApplication.instance()
    if app is None:
        app = QtGui.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(QtGui.QApplication.exec_())


if __name__ == "__main__":
    main()