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?
在Rails中，我是这样做的:
function download_file(file_id) {
let url = '/files/' + file_id + '/download_file';
$.ajax({
type: 'GET',
url: url,
processData: false,
success: function (data) {
window.location = url;
},
error: function (xhr) {
console.log(' Error: >>>> ' + JSON.stringify(xhr));
}
});
}
诀窍在于窗户。位置的部分。控制器的方法如下所示:
# GET /files/{:id}/download_file/
def download_file
send_file(@file.file,
:disposition => 'attachment',
:url_based_filename => false)
end
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);
}
});
});
这是我所做的，纯javascript和html。没有测试，但这应该在所有浏览器工作。
Javascript函数
var iframe = document.createElement('iframe');
iframe.id = "IFRAMEID";
iframe.style.display = 'none';
document.body.appendChild(iframe);
iframe.src = 'SERVERURL'+'?' + $.param($scope.filtro);
iframe.addEventListener("load", function () {
console.log("FILE LOAD DONE.. Download should start now");
});
只使用所有浏览器都支持的组件，不添加其他组件
库。
下面是我的服务器端JAVA Spring控制器代码。
@RequestMapping(value = "/rootto/my/xlsx", method = RequestMethod.GET)
public void downloadExcelFile(@RequestParam(value = "param1", required = false) String param1,
HttpServletRequest request, HttpServletResponse response)
throws ParseException {
Workbook wb = service.getWorkbook(param1);
if (wb != null) {
try {
String fileName = "myfile_" + sdf.format(new Date());
response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
response.setHeader("Content-disposition", "attachment; filename=\"" + fileName + ".xlsx\"");
wb.write(response.getOutputStream());
response.getOutputStream().close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
我创建了一个小函数作为解决方案(灵感来自@JohnCulviner插件):
// creates iframe and form in it with hidden field,
// then submit form with provided data
// url - form url
// data - data to form field
// input_name - form hidden input name
function ajax_download(url, data, input_name) {
var $iframe,
iframe_doc,
iframe_html;
if (($iframe = $('#download_iframe')).length === 0) {
$iframe = $("<iframe id='download_iframe'" +
" style='display: none' src='about:blank'></iframe>"
).appendTo("body");
}
iframe_doc = $iframe[0].contentWindow || $iframe[0].contentDocument;
if (iframe_doc.document) {
iframe_doc = iframe_doc.document;
}
iframe_html = "<html><head></head><body><form method='POST' action='" +
url +"'>" +
"<input type=hidden name='" + input_name + "' value='" +
JSON.stringify(data) +"'/></form>" +
"</body></html>";
iframe_doc.open();
iframe_doc.write(iframe_html);
$(iframe_doc).find('form').submit();
}
演示点击事件:
$('#someid').on('click', function() {
ajax_download('/download.action', {'para1': 1, 'para2': 2}, 'dataname');
});
你可以用HTML5
注意:返回的文件数据必须是base64编码的，因为JSON不能编码二进制数据
在我的AJAX响应中，我有一个看起来像这样的数据结构:
{
result: 'OK',
download: {
mimetype: string(mimetype in the form 'major/minor'),
filename: string(the name of the file to download),
data: base64(the binary data as base64 to download)
}
}
这意味着我可以执行以下操作来通过AJAX保存文件
var a = document.createElement('a');
if (window.URL && window.Blob && ('download' in a) && window.atob) {
// Do it the HTML5 compliant way
var blob = base64ToBlob(result.download.data, result.download.mimetype);
var url = window.URL.createObjectURL(blob);
a.href = url;
a.download = result.download.filename;
a.click();
window.URL.revokeObjectURL(url);
}
函数base64ToBlob是从这里取的，必须按照这个函数使用
function base64ToBlob(base64, mimetype, slicesize) {
if (!window.atob || !window.Uint8Array) {
// The current browser doesn't have the atob function. Cannot continue
return null;
}
mimetype = mimetype || '';
slicesize = slicesize || 512;
var bytechars = atob(base64);
var bytearrays = [];
for (var offset = 0; offset < bytechars.length; offset += slicesize) {
var slice = bytechars.slice(offset, offset + slicesize);
var bytenums = new Array(slice.length);
for (var i = 0; i < slice.length; i++) {
bytenums[i] = slice.charCodeAt(i);
}
var bytearray = new Uint8Array(bytenums);
bytearrays[bytearrays.length] = bytearray;
}
return new Blob(bytearrays, {type: mimetype});
};
如果您的服务器正在转储要保存的文件数据，这很好。然而，我还没有完全弄清楚如何实现HTML4的回退
