Python下载文件的11种方式
<img src="https://p3-sign.toutiaoimg.com/pgc-image/RvXPGX0FpO2xYv~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=fKXRhkcphAvpOtW4NeDiQch3%2Fso%3D" style="width: 50%; margin-bottom: 20px;"><p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在本教程中，你将学习<span style="color: black;">怎样</span><span style="color: black;">运用</span><span style="color: black;">区别</span>的Python模块从web下载文件。<span style="color: black;">另外</span>，你将下载常规文件、web页面、Amazon S3和其他资源。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">最后，你将学习<span style="color: black;">怎样</span>克服可能遇到的<span style="color: black;">各样</span>挑战，例如下载重定向的文件、下载大型文件、完成一个多线程下载以及其他策略。</p>
<h1 style="color: black; text-align: left; margin-bottom: 10px;"><span style="color: black;">运用</span>Requests</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">你<span style="color: black;">能够</span><span style="color: black;">运用</span>requests模块从一个URL下载文件。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">思虑</span>以下代码:</p><img src="https://p26-sign.toutiaoimg.com/pgc-image/Rye5o6Z7r1LOw8~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=8glMLL4uR%2BCXj4kyL%2F9yJVPyE%2B8%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">你只需<span style="color: black;">运用</span>requests模块的get<span style="color: black;">办法</span>获取URL，并将结果存储到一个名为“myfile”的变量中。<span style="color: black;">而后</span>，将这个变量的内容写入文件。</p>
<h1 style="color: black; text-align: left; margin-bottom: 10px;"><span style="color: black;">运用</span>wget</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">你还<span style="color: black;">能够</span><span style="color: black;">运用</span>Python的wget模块从一个URL下载文件。你<span style="color: black;">能够</span><span style="color: black;">运用</span>pip按以下命令安装wget模块:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5o7EGs1ItuP~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=M4SoD7bb7aCHvgMuLEATWQaOU0Y%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">思虑</span>以下代码，<span style="color: black;">咱们</span>将<span style="color: black;">运用</span>它下载Python的logo图像。</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5o7qJ3qgaqf~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=D3sKIEs0HIDGDtjHYxwsFsq76oA%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在这段代码中，URL和路径(图像将存储在其中)被传递给wget模块的download<span style="color: black;">办法</span>。</p>
<h1 style="color: black; text-align: left; margin-bottom: 10px;">下载重定向的文件</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在本节中，你将学习<span style="color: black;">怎样</span><span style="color: black;">运用</span>requests从一个URL下载文件，该URL会被重定向到另一个带有一个.pdf文件的URL。该URL看起来如下:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5o8QEBJdFa1~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=iBdSeU4W0vW1LoqJ5Uv6KGK4qis%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">要下载这个pdf文件，请<span style="color: black;">运用</span>以下代码:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5oUZ6lScY0y~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=LvQ4jbHmYBbGkJO6LEFuiVTjw6Q%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在这段代码中，<span style="color: black;">咱们</span><span style="color: black;">第1</span>步指定的是URL。<span style="color: black;">而后</span>，<span style="color: black;">咱们</span><span style="color: black;">运用</span>request模块的get<span style="color: black;">办法</span>来获取该URL。在get<span style="color: black;">办法</span>中，<span style="color: black;">咱们</span>将allow_redirects设置为True，这将<span style="color: black;">准许</span>URL中的重定向，并且重定向后的内容将被分配给变量myfile。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">最后，<span style="color: black;">咱们</span>打开一个文件来写入获取的内容。</p>
<h1 style="color: black; text-align: left; margin-bottom: 10px;">分块下载大文件</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">思虑</span>下面的代码:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5oUzIGbbS1o~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=2vFRBHMR2UVlJxYEFGmeduq1N1U%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">首要</span>，<span style="color: black;">咱们</span>像以前<span style="color: black;">同样</span><span style="color: black;">运用</span>requests模块的get<span style="color: black;">办法</span>，<span style="color: black;">然则</span>这一次，<span style="color: black;">咱们</span>将把stream属性设置为True。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">接着，<span style="color: black;">咱们</span>在当前工作目录中创建一个名为PythonBook.pdf的文件，并打开它进行写入。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">而后</span>，<span style="color: black;">咱们</span>指定每次要下载的块<span style="color: black;">体积</span>。<span style="color: black;">咱们</span><span style="color: black;">已然</span>将其设置为1024字节，接着遍历<span style="color: black;">每一个</span>块，并在文件中写入这些块，直到块结束。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">不<span style="color: black;">美丽</span>吗?不要担心，稍后<span style="color: black;">咱们</span>将<span style="color: black;">表示</span>一个下载过程的进度条。</p>
<h1 style="color: black; text-align: left; margin-bottom: 10px;">下载多个文件(并行/批量下载)</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">要<span style="color: black;">同期</span>下载多个文件，请导入以下模块:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5oVZ6VU2ftf~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=pTBURCyOQBU62XJD59y66aDyqfg%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">咱们</span>导入了os和time模块来<span style="color: black;">检测</span>下载文件<span style="color: black;">必须</span>多少时间。ThreadPool模块<span style="color: black;">准许</span>你<span style="color: black;">运用</span>池运行多个线程或进程。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">让<span style="color: black;">咱们</span>创建一个简单的函数，将响应分块发送到一个文件:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5oW77TiynWN~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=%2FMWAK0Lj47nUUGh9yGm%2BiGhoDnc%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">这个URL是一个二维数组，它指定了你要下载的页面的路径和URL。</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5oWdAaWsxz5~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=mj4FowJygkXY3HTY5cWIyK9fURg%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">就像在前一节中所做的那样，<span style="color: black;">咱们</span>将这个URL传递给requests.get。最后，<span style="color: black;">咱们</span>打开文件(URL中指定的路径)并写入页面内容。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">此刻</span>，<span style="color: black;">咱们</span><span style="color: black;">能够</span>分别为<span style="color: black;">每一个</span>URL调用这个函数，<span style="color: black;">咱们</span><span style="color: black;">亦</span><span style="color: black;">能够</span><span style="color: black;">同期</span>为所有URL调用这个函数。让<span style="color: black;">咱们</span>在for循环中分别为<span style="color: black;">每一个</span>URL调用这个函数，<span style="color: black;">重视</span>计时器:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5oyhC1Nc4Sd~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=RGRGASzisB83EAQyYxvmbzHGfwY%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">此刻</span>，<span style="color: black;">运用</span>以下代码行替换for循环：</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5ozN6hiLkP8~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=qLkViVN%2FXJHc72SJ6h9uBsMv47M%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">运行该脚本。</p>
<h1 style="color: black; text-align: left; margin-bottom: 10px;"><span style="color: black;">运用</span>进度条进行下载</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">进度条是clint模块的一个UI组件。输入以下命令来安装clint模块：</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5p006kU05HN~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=DEERMOX9JghUIrTAbdRo48J%2F30I%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">思虑</span>以下代码:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5p0gmVvoed~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=ALf%2FK1qinntYShog9EAlSLHV7YM%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在这段代码中，<span style="color: black;">咱们</span><span style="color: black;">首要</span>导入了requests模块，<span style="color: black;">而后</span>，<span style="color: black;">咱们</span>从clint.textui导入了进度组件。<span style="color: black;">独一</span>的区别是在for循环中。在将内容写入文件时，<span style="color: black;">咱们</span><span style="color: black;">运用</span>了进度条模块的bar<span style="color: black;">办法</span>。</p>
<h1 style="color: black; text-align: left; margin-bottom: 10px;"><span style="color: black;">运用</span>urllib下载网页</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在本节中，<span style="color: black;">咱们</span>将<span style="color: black;">运用</span>urllib下载一个网页。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">urllib库是Python的标准库，<span style="color: black;">因此呢</span>你不<span style="color: black;">必须</span>安装它。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">以下代码行<span style="color: black;">能够</span><span style="color: black;">容易</span>地下载一个网页:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5p1EHW7B7J6~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=%2FWhs31QQII3fgRefRV8XVrm%2B8mg%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在<span style="color: black;">这儿</span>指定你想将文件<span style="color: black;">保留</span>为什么以及你想将它存储在哪里的URL，</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5ph5Ef3aDog~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=sEHzIWKGiPuZrsdn0aJ5Mn5VICI%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在这段代码中，<span style="color: black;">咱们</span><span style="color: black;">运用</span>了urlretrieve<span style="color: black;">办法</span>并传递了文件的URL，以及<span style="color: black;">保留</span>文件的路径。文件扩展名将是.html。</p>
<h1 style="color: black; text-align: left; margin-bottom: 10px;"><span style="color: black;">经过</span>代理下载</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">倘若</span>你<span style="color: black;">必须</span><span style="color: black;">运用</span>代理下载你的文件，你<span style="color: black;">能够</span><span style="color: black;">运用</span>urllib模块的ProxyHandler。请看以下代码：</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5phg3n2ZAGN~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=ph7R8Nw%2B8F6%2FqjE0GyZzANCnCiA%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在这段代码中，<span style="color: black;">咱们</span>创建了代理对象，并<span style="color: black;">经过</span>调用urllib的build_opener<span style="color: black;">办法</span>来打开该代理，并传入该代理对象。<span style="color: black;">而后</span>，<span style="color: black;">咱们</span>创建请求来获取页面。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">另外</span>，你还<span style="color: black;">能够</span><span style="color: black;">根据</span>官方文档的介绍来<span style="color: black;">运用</span>requests模块:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5pi75o5BdmI~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=VylFzHATqhxENImH1APLSoEqNb0%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">你只<span style="color: black;">必须</span>导入requests模块并创建你的代理对象。<span style="color: black;">而后</span>，你就<span style="color: black;">能够</span>获取文件了。</p>
<h1 style="color: black; text-align: left; margin-bottom: 10px;"><span style="color: black;">运用</span>urllib3</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">urllib3是urllib模块的改进版本。你<span style="color: black;">能够</span><span style="color: black;">运用</span>pip下载并安装它:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5pig6zSnAW2~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=Nsi1mzqlQv9bO2sZPQSMNar3uaY%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">咱们</span>将<span style="color: black;">经过</span><span style="color: black;">运用</span>urllib3来获取一个网页并将它存储在一个文本文件中。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">导入以下模块:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5pjKB8JGIze~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=MOvQzPDIXOWX157oW1wPUpiq7%2BM%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在处理文件时，<span style="color: black;">咱们</span><span style="color: black;">运用</span>了shutil模块。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">此刻</span>，<span style="color: black;">咱们</span>像<span style="color: black;">这般</span>来初始化URL字符串变量：</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5q9j8PqL5KW~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=icbNYTR59s2fIG0FTqHwSQACB10%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">而后</span>，<span style="color: black;">咱们</span><span style="color: black;">运用</span>了urllib3的PoolManager ，它会跟踪必要的连接池。</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5qAOBZ0xZoo~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=xPH6EhKwrYZc4%2FE1zBAA0mYRjTY%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">创建一个文件:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5qB2HV6XUNA~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=TRjg0UiJFLhoErK6VNzrc1VcO1o%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">最后，<span style="color: black;">咱们</span>发送一个GET请求来获取该URL并打开一个文件，接着将响应写入该文件:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5qBbH0OqDa2~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=BFckuohblIXlQC4a78TC9dRqlYY%3D" style="width: 50%; margin-bottom: 20px;">
<h1 style="color: black; text-align: left; margin-bottom: 10px;"><span style="color: black;">运用</span>Boto3从S3下载文件</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">要从Amazon S3下载文件，你<span style="color: black;">能够</span><span style="color: black;">运用</span>Python boto3模块。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在<span style="color: black;">起始</span>之前，你<span style="color: black;">必须</span><span style="color: black;">运用</span>pip安装awscli模块:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5qC5FkdR98t~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=BZEyAfiJppVJTMR97elcDLZuP9Y%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">针对</span>AWS配置，请运行以下命令：</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5qey9yot3to~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=QEOiABYixb68gc%2BIU1OCDS6kZWA%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">此刻</span>，按以下命令输入你的<span style="color: black;">仔细</span>信息：</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5qfasHYdEB~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=zPsL5FBbndsAgYLxOcZSZMgivos%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">要从Amazon S3下载文件，你<span style="color: black;">必须</span>导入boto3和botocore。Boto3是一个Amazon SDK，它<span style="color: black;">准许</span>Python<span style="color: black;">拜访</span>Amazon web服务(如S3)。Botocore<span style="color: black;">供给</span>了与Amazon web服务进行交互的命令行服务。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">Botocore自带了awscli。要安装boto3，请运行以下命令:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5qgDC4S2tCh~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=dbvRasM0sF9R8IkZN8Ox%2BTIqmrM%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">此刻</span>，导入这两个模块：</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5qgi8pxU2eY~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=sU7t2qm2%2B7aXNe0TlBunn456Rks%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在从Amazon下载文件时，<span style="color: black;">咱们</span><span style="color: black;">必须</span>三个参数：</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">Bucket名<span style="color: black;">叫作</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">你<span style="color: black;">必须</span>下载的文件名<span style="color: black;">叫作</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">文件下载之后的名<span style="color: black;">叫作</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">初始化变量：</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5qhGCsFkSlW~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=RuBpx1wggA4fJzxIIoQqXtrPejw%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">此刻</span>，<span style="color: black;">咱们</span>初始化一个变量来<span style="color: black;">运用</span>会话的资源。为此，<span style="color: black;">咱们</span>将调用boto3的resource<span style="color: black;">办法</span>并传入服务，即s3:</p><img src="https://p26-sign.toutiaoimg.com/pgc-image/Rye5rCsCTApdyu~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=3lFo2pR3bFw4UcM20%2F2dS2Zjtuw%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">最后，<span style="color: black;">运用</span>download_file<span style="color: black;">办法</span>下载文件并传入变量:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5rDZ290CdYC~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=99dKkCTItwfGODjkCW1T4tbvAA0%3D" style="width: 50%; margin-bottom: 20px;">
<h1 style="color: black; text-align: left; margin-bottom: 10px;"><span style="color: black;">运用</span>asyncio</h1>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">asyncio模块<span style="color: black;">重点</span>用于处理系统事件。它围绕一个事件循环进行工作，该事件循环会等待事件<span style="color: black;">出现</span>，<span style="color: black;">而后</span>对该事件作出反应。这个反应<span style="color: black;">能够</span>是调用另一个函数。这个过程<span style="color: black;">叫作</span>为事件处理。asyncio模块<span style="color: black;">运用</span>协同程序进行事件处理。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">要<span style="color: black;">运用</span>asyncio事件处理和协同功能，<span style="color: black;">咱们</span>将导入asyncio模块:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5rEBCKh2XBT~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=FlPvbocaZ2pDZ0kAne4tfSgZKEA%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">此刻</span>，像<span style="color: black;">这般</span>定义asyncio协同<span style="color: black;">办法</span>：</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5rEjDz54Mbf~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=WTdR2CcBoHIPblZ5O3lYWYjlht0%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">关键字async<span style="color: black;">暗示</span>这是一个原生asyncio协同程序。在协同程序的内部，<span style="color: black;">咱们</span>有一个await关键字，它会返回一个特定的值。<span style="color: black;">咱们</span><span style="color: black;">亦</span><span style="color: black;">能够</span><span style="color: black;">运用</span>return关键字。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">此刻</span>，让<span style="color: black;">咱们</span><span style="color: black;">运用</span>协同创建一段代码来从网站下载一个文件:</p><img src="https://p3-sign.toutiaoimg.com/pgc-image/Rye5rFHGZCWu51~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=qUzCOIY9Tjd4qK9egNxAMnCiCjk%3D" style="width: 50%; margin-bottom: 20px;">
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在这段代码中，<span style="color: black;">咱们</span>创建了一个异步协同函数，它会下载<span style="color: black;">咱们</span>的文件并返回一条<span style="color: black;">信息</span>。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">而后</span>，<span style="color: black;">咱们</span><span style="color: black;">运用</span>另一个异步协同程序调用main_func，它会等待URL并将所有URL<span style="color: black;">构成</span>一个队列。asyncio的wait函数会等待协同程序完成。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">此刻</span>，为了<span style="color: black;">起步</span>协同程序，<span style="color: black;">咱们</span><span style="color: black;">必要</span><span style="color: black;">运用</span>asyncio的get_event_loop<span style="color: black;">办法</span>将协同程序放入事件循环中，最后，<span style="color: black;">咱们</span><span style="color: black;">运用</span>asyncio的run_until_complete<span style="color: black;">办法</span>执行该事件循环。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">运用</span>Python下载文件是<span style="color: black;">特别有</span>趣的。<span style="color: black;">期盼</span>本教程对你有用!</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">英文原文：https://dzone.com/articles/simple-examples-of-downloading-files-using-python</p>译者：天天向上<img src="https://p3-sign.toutiaoimg.com/pgc-image/RvXPKnU5vYMwDH~noop.image?_iz=58558&from=article.pc_detail&lk3s=953192f4&x-expires=1723897141&x-signature=1XJm5ipSnTbxyKBPCfZucSoSKBQ%3D" style="width: 50%; margin-bottom: 20px;">
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