OSS post object方式 出现MalformedPOSTRequest错误

安卓端利用post object方式，出现了MalformedPOSTRequest错误，由于和其他端保持统一，没有使用SDK
报文中的accessid和sign等已去除，这块没有问题，使用php、js都能上传成功，不知道为何安卓不行


抓取报文如下：

POST / HTTP/1.1
Content-Type: multipart/form-data; boundary=94a318c4-dd12-4dee-b7d8-51bede02f1e9
Content-Length: 39986
Host: loan-file.oss-cn-beijing.aliyuncs.com
Connection: Keep-Alive
Accept-Encoding: gzip
User-Agent: okhttp/2.5.0


--94a318c4-dd12-4dee-b7d8-51bede02f1e9
Content-Disposition: form-data; name="Callback"
Content-Transfer-Encoding: binary
Content-Type: text/plain; charset=utf-8
Content-Length: 312


11111......................（安全问题，已去除）
--94a318c4-dd12-4dee-b7d8-51bede02f1e9
Content-Disposition: form-data; name="OSSAccessKeyId"
Content-Transfer-Encoding: binary
Content-Type: text/plain; charset=utf-8
Content-Length: 16


11111111111（安全问题，已去除）
--94a318c4-dd12-4dee-b7d8-51bede02f1e9
Content-Disposition: form-data; name="policy"
Content-Transfer-Encoding: binary
Content-Type: text/plain; charset=utf-8
Content-Length: 120


1111111111111111（安全问题，已去除）
--94a318c4-dd12-4dee-b7d8-51bede02f1e9
Content-Disposition: form-data; name="key"
Content-Transfer-Encoding: binary
Content-Type: text/plain; charset=utf-8
Content-Length: 25


aaatitle1447916971206.jpg
--94a318c4-dd12-4dee-b7d8-51bede02f1e9
Content-Disposition: form-data; name="Signature"
Content-Transfer-Encoding: binary
Content-Type: text/plain; charset=utf-8
Content-Length: 28


111111111111（安全问题，已去除）
--94a318c4-dd12-4dee-b7d8-51bede02f1e9
Content-Disposition: form-data; name="file"; filename="title1447916971206.jpg"
Content-Transfer-Encoding: binary
Content-Type: image/jpeg
Content-Length: 38288


-------------文件流--------
--94a318c4-dd12-4dee-b7d8-51bede02f1e9