如何通过 QNetworkAccessManager 找出下载图像的确切 url

Question

我正在使用QNetworkAccessManager 下载图片。

第一次一定要指定图片的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。

即使我将它传递给QNetworkRequest，我也无法下载图像。

在我挖掘 url 并到达Wikipedia Commons 中的图像文件后， 如果我将 url 传递给QNetworkRequest，我可以下载图片。

我已经知道url一定要准确，但是不知道怎么区分。

您知道如何每次都以编程方式下载图像而不会出错吗？

有没有办法提前知道具体的url？

我对网络了解不多。

我经常接受UnknownContentError

示例代码的使用方法

Ctrl+C 复制文字和图片（请包含图片。） Ctrl+V粘贴html并下载图片

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 url 在子 img 标签的 src 属性中。
• 您只需要创建一个 QNetworkAccessManager，否则新的 QNetworkAccessManager 会删除之前的。
• 您必须使用QUrl::fromUserInput()，因为它会处理尝试多种配置的 url，例如在这种情况下它可以转换以下网址：

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

到

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()