我正在尝试使用此代码发送带有 XMLHttpRequest 的文件。

var url= "http://localhost:80/....";
$(document).ready(function(){
    document.getElementById('upload').addEventListener('change', function(e) {
        var file = this.files[0];
        var xhr = new XMLHttpRequest();
        xhr.file = file; // not necessary if you create scopes like this
        xhr.addEventListener('progress', function(e) {
            var done = e.position || e.loaded, total = e.totalSize || e.total;
            console.log('xhr progress: ' + (Math.floor(done/total*1000)/10) + '%');
        }, false);
        if ( xhr.upload ) {
            xhr.upload.onprogress = function(e) {
                var done = e.position || e.loaded, total = e.totalSize || e.total;
                console.log('xhr.upload progress: ' + done + ' / ' + total + ' = ' + (Math.floor(done/total*1000)/10) + '%');
            };
        }
        xhr.onreadystatechange = function(e) {
            if ( 4 == this.readyState ) {
                console.log(['xhr upload complete', e]);
            }
        };
        xhr.open('post', url, true);
        xhr.setRequestHeader("Content-Type","multipart/form-data");
        xhr.send(file);
    }, false);
});

我收到此错误：T

请求被拒绝，因为未找到多部分边界。

我究竟做错了什么？