我在服务器端有一个Struts2操作用于文件下载。
<action name="download" class="com.xxx.DownAction">
<result name="success" type="stream">
<param name="contentType">text/plain</param>
<param name="inputName">imageStream</param>
<param name="contentDisposition">attachment;filename={fileName}</param>
<param name="bufferSize">1024</param>
</result>
</action>
然而，当我使用jQuery调用动作时:
$.post(
"/download.action",{
para1:value1,
para2:value2
....
},function(data){
console.info(data);
}
);
在Firebug中，我看到数据是用二进制流检索的。我想知道如何打开文件下载窗口，用户可以在本地保存文件?
2019现代浏览器更新
这是我现在推荐的方法，但有几点注意事项:
需要一个相对现代的浏览器
如果文件非常大，您可能会采取与原始方法(iframe和cookie)类似的方法，因为以下一些操作可能会消耗至少与正在下载的文件相同大的系统内存和/或其他有趣的CPU副作用。
fetch('https://jsonplaceholder.typicode.com/todos/1')
.then(resp => resp.blob())
.then(blob => {
const url = window.URL.createObjectURL(blob);
const a = document.createElement('a');
a.style.display = 'none';
a.href = url;
// the filename you want
a.download = 'todo-1.json';
document.body.appendChild(a);
a.click();
window.URL.revokeObjectURL(url);
alert('your file has downloaded!'); // or you know, something with better UX...
})
.catch(() => alert('oh no!'));
2012年原创jQuery/iframe/Cookie的方法
Bluish在这一点上是完全正确的，你不能通过Ajax做到这一点，因为JavaScript不能直接将文件保存到用户的计算机(出于安全考虑)。不幸的是，将主窗口的URL指向您的文件下载意味着当文件下载发生时，您几乎无法控制用户体验。
我创建了jQuery文件下载，它允许“类似Ajax”的体验，文件下载完成OnSuccess和OnFailure回调，以提供更好的用户体验。看看我的博客文章，关于这个插件解决的常见问题和一些使用它的方法，还有一个jQuery文件下载的演示。这是来源
下面是一个简单的用例演示，使用带有承诺的插件源代码。演示页面还包括许多其他“更好的用户体验”示例。
$.fileDownload('some/file.pdf')
.done(function () { alert('File download a success!'); })
.fail(function () { alert('File download failed!'); });
取决于你需要支持什么浏览器，你可以使用https://github.com/eligrey/FileSaver.js/，它允许比jQuery文件下载使用的IFRAME方法更明确的控制。
I found a fix that while it's not actually using ajax it does allow you to use a javascript call to request the download and then get a callback when the download actually starts. I found this helpful if the link runs a server side script that takes a little bit to compose the file before sending it. so you can alert them that it's processing, and then when it does finally send the file remove that processing notification. which is why I wanted to try to load the file via ajax to begin with so that I could have an event happen when the file is requested and another when it actually starts downloading.
js在首页
function expdone()
{
document.getElementById('exportdiv').style.display='none';
}
function expgo()
{
document.getElementById('exportdiv').style.display='block';
document.getElementById('exportif').src='test2.php?arguments=data';
}
iframe
<div id="exportdiv" style="display:none;">
<img src="loader.gif"><br><h1>Generating Report</h1>
<iframe id="exportif" src="" style="width: 1px;height: 1px; border:0px;"></iframe>
</div>
然后是另一个文件:
<!DOCTYPE html>
<html>
<head>
<script>
function expdone()
{
window.parent.expdone();
}
</script>
</head>
<body>
<iframe id="exportif" src="<?php echo "http://10.192.37.211/npdtracker/exportthismonth.php?arguments=".$_GET["arguments"]; ?>"></iframe>
<script>document.getElementById('exportif').onload= expdone;</script>
</body></html>
我认为有一种方法可以使用js读取数据，这样就不需要php了。但我不知道它的手，我正在使用的服务器支持php，所以这对我有用。我想分享一下，也许能帮到别人。
HTML代码:
<button type="button" id="GetFile">Get File!</button>
jQuery代码:
$('#GetFile').on('click', function () {
$.ajax({
url: 'https://s3-us-west-2.amazonaws.com/s.cdpn.io/172905/test.pdf',
method: 'GET',
xhrFields: {
responseType: 'blob'
},
success: function (data) {
var a = document.createElement('a');
var url = window.URL.createObjectURL(data);
a.href = url;
a.download = 'myfile.pdf';
document.body.append(a);
a.click();
a.remove();
window.URL.revokeObjectURL(url);
}
});
});
我的方法完全基于jQuery。对我来说，问题是它必须是一个POST-HTTP调用。我希望它是由jQuery单独完成。
解决方案:
$.ajax({
type: "POST",
url: "/some/webpage",
headers: {'X-CSRF-TOKEN': csrfToken},
data: additionalDataToSend,
dataType: "text",
success: function(result) {
let blob = new Blob([result], { type: "application/octetstream" });
let a = document.createElement('a');
a.href = window.URL.createObjectURL(blob);
a.download = "test.xml";;
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
window.URL.revokeObjectURL(a.href);
...
},
error: errorDialog
});
解释:
我和很多人所做的是在网页上创建一个链接，指出应该下载目标，并将http-request的结果作为目标。之后，我将链接附加到文档，而不是简单地单击链接，然后删除链接。你不再需要iframe了。
神奇之处在于线条
let blob = new Blob([result], { type: "application/octetstream" });
a.href = window.URL.createObjectURL(blob);
The interesting point is that this solution is only working with a "blob". As you can see in other answers, some are simply using a blob but not explaining why and how to create it.
As you can read e.g. in the Mozilla developer documentation you need a file, media ressource or blob for the function "createObjectURL()" to work. The problem is that your http-response might not be any of those.
Therefore the first thing you must do is to convert your response to a blob. This is what the first line does. Then you can use the "createObjectURL" with your newly created blob.
If you than click the link your browser will open a file-save dialog and you can save your data. Obviously it s possible that you cannot define a fixed filename for your file to download. Then you must make your response more complex like in the answer from Luke.
不要忘记释放内存，特别是在处理大文件时。要获得更多的示例和信息，您可以查看JS blob对象的详细信息
