使用POST FORM / AJAX下载文件？

Question

I need to download a CSV file for my respective table in a page. I don't need to do any action after Download, just that he says Export and the data gets downloaded into CSV file. The back end code is ready, but how do I do it using POST.

I've referred many suggestions, and tried using window.open but POST seems to be a problem there. Finally tried with FORM creation, but now the issue is I get

"415 unsupported media type"

My Request header

Accept  text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Encoding gzip, deflate
Accept-Language en-US,en;q=0.5
Connection  keep-alive
User-Agent  Mozilla/5.0 (Windows NT 6.1; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0
Content-Length  112
Content-Type    application/x-www-form-urlencoded

Now what I understand is to fix this my content type should be set to JSON, and that's not possible in FORM POST?

1) Do we have a better way to Download a file (For a Single page APP using HTML and JS)? NO Library please, plain Javascript Way, getting approval for library is not possible in my project.

2) How can I fix the above issue, If not what are my other options?

Code :

    var form = document.createElement("form");
    form.id = formId;
    form.action = url;
    form.method = method || "POST";
    form.target = target || "_self";
    if (data) {
        for (var key in data) {
            var input = document.createElement("textarea");
            input.name = key;
            input.value = typeof data[key] === "object" ? JSON.stringify(data[key]) : data[key];
            form.appendChild(input);
        }
    }
    form.style.display = 'none';
    $('#' + containerId).append(form);
    if (!self.isEmptyObject(data)) {
        form.submit();
    }

Answer 1

The fix was required from REST End point

Include below Code

@Consumes({MediaType.APPLICATION_JSON, MediaType.APPLICATION_FORM_URLENCODED})

and changed the params to

public javax.ws.rs.core.Response getExceptionDetailLogs(final @FormParam("param1") String param1,
    final @FormParam("param2") String param2) throws Exception {
    ....
}   

Answer 2

Here i have done one example make sure helpful to all :

<form name="myform" id="myform" method="post" enctype= "multipart/form-data">
    <input name="uploadData" id="uploadData" type="file"/>
</form>

$("#uploadData").change(function (e) {
    $('.loading').show();
        var file_data = $('#uploadData').prop('files')[0];
        var form_data = new FormData();
        var csvhtml = '';
        form_data.append('file', file_data);
        $.ajax({
            url: '{{path('bulk_request_update_upload')}}',
            dataType: 'text',
            cache: false,
            contentType: false,
            processData: false,
            data: form_data,
            type: 'post',
            success: function (data) {
        }
    });
});