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?
这就是它在任何浏览器中都很好(我使用asp.net核心)
function onDownload() {
const api = '@Url.Action("myaction", "mycontroller")';
var form = new FormData(document.getElementById('form1'));
fetch(api, { body: form, method: "POST"})
.then(resp => resp.blob())
.then(blob => {
const url = window.URL.createObjectURL(blob);
$('#linkdownload').attr('download', 'Attachement.zip');
$('#linkdownload').attr("href", url);
$('#linkdownload')
.fadeIn(3000,
function() { });
})
.catch(() => alert('An error occurred'));
}
<button type="button" onclick="onDownload()" class="btn btn-primary btn-sm">Click to Process Files</button>
<a role="button" href="#" style="display: none" class="btn btn-sm btn-secondary" id="linkdownload">Click to download Attachments</a>
<form asp-controller="mycontroller" asp-action="myaction" id="form1"></form>
function onDownload() {
const api = '@Url.Action("myaction", "mycontroller")';
//form1 is your id form, and to get data content of form
var form = new FormData(document.getElementById('form1'));
fetch(api, { body: form, method: "POST"})
.then(resp => resp.blob())
.then(blob => {
const url = window.URL.createObjectURL(blob);
$('#linkdownload').attr('download', 'Attachments.zip');
$('#linkdownload').attr("href", url);
$('#linkdownload')
.fadeIn(3000,
function() {
});
})
.catch(() => alert('An error occurred'));
}
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
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();
}
}
}
在上面添加一些东西来下载文件
下面是一些生成字节数组的java spring代码
@RequestMapping(value = "/downloadReport", method = { RequestMethod.POST })
public ResponseEntity<byte[]> downloadReport(
@RequestBody final SomeObejct obj, HttpServletResponse response) throws Exception {
OutputStream out = new ByteArrayOutputStream();
// write something to output stream
HttpHeaders respHeaders = new HttpHeaders();
respHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);
respHeaders.add("X-File-Name", name);
ByteArrayOutputStream bos = (ByteArrayOutputStream) out;
return new ResponseEntity<byte[]>(bos.toByteArray(), respHeaders, HttpStatus.CREATED);
}
现在在javascript代码中使用filesver .js，可以下载带有下面代码的文件
var json=angular.toJson("somejsobject");
var url=apiEndPoint+'some url';
var xhr = new XMLHttpRequest();
//headers('X-File-Name')
xhr.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 201) {
var res = this.response;
var fileName=this.getResponseHeader('X-File-Name');
var data = new Blob([res]);
saveAs(data, fileName); //this from FileSaver.js
}
}
xhr.open('POST', url);
xhr.setRequestHeader('Authorization','Bearer ' + token);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.responseType = 'arraybuffer';
xhr.send(json);
以上将下载文件
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
