分片上传失败，和本来的app.js是一样的，但是400错误

var uploadFile = function (client) {
var file = document.getElementById('file').files[0];
//var key = document.getElementById('object-key-file').value.trim() || 'object';
//console.log(file.name + ' => ' + key);

if(file.size>(1024*1024*2)){
    alert('请上传2M以下的图片！')
    return;
}

return client.multipartUpload(url_+file.name, file, {

progress: progress

}).then(function (res) {

console.log('upload success: %j', res);
//return listFiles(client);
location.href='';

});
};