此操作用于获取指定的Object内容
请求语法
GET /ObjectName HTTP/1.1 Host: BucketName. s.jcloud.com Date: GMT Date Authorization: signatureValue#请参照“访问控制” Range: bytes=ByteRange(可选)
Range 指定获取的Object数据内容，如设定 bytes=0-9，表示传送第0到第9这10个字符，更多的信息可以参看《RFC2616》
细节分析 1.GetObject通过range参数可以支持断点续传，对于比较大的Object建议使用该功能。
2.如果在请求头中使用Range参数；则返回消息中会包含整个文件的长度和此次返回的范围，例如：Content-Range: bytes 0-9/44，表示整个文件长度为44。
3.如果文件不存在，返回404 Not Found错误。错误码：NoSuchKey。
4.若该Object为进行服务器加密存储的，则在GET请求时会自动解密返回给用户。
请求示例
GET /example.jpg HTTP/1.1 Host: oss-example.s-bj.jcloud.com Date: Tue, 11 Jul 2017 07:28:01 GMT Authorization: jingdong qbS5QXpLORrvdrmb:Ctm+uA40JmY3T3LvCZ6CkKkANXs=
HTTP/1.1 200 OK Server: nginx Date: Tue, 11 Jul 2017 07:28:01 GMT Content-Type: text/plain Content-Length: 13 Connection: keep-alive x-jss-request-id: 95CB505F50E9341D Cache-Control: max-age=2592000 Content-Disposition: inline; filename="example.jpg" Accept-Ranges: bytes ETag: "6457646542258052f767868fd686d74d" Last-Modified: Tue, 11 Jul 2017 07:27:15 GMT x-jss-storage-class: STANDARD X-Trace: 200-1499758081049-0-0-19-45-45
GET example.jpg HTTP/1.1 Host: oss-example.s-bj.jcloud.com Range: bytes=0-9 Date: Tue, 11 Jul 2017 07:34:11 GMT Authorization: jingdong qbS5QXpLORrvdrmb:/Aaawoo0xVq4XVMei/yK1UqhoFc=
HTTP/1.1 206 Partial Content Server: nginx Date: Tue, 11 Jul 2017 07:34:11 GMT Content-Type: text/plain Content-Length: 10 Connection: keep-alive Content-Range: bytes 0-9/13 x-jss-request-id: A0D975825710D969 Cache-Control: max-age=2592000 Content-Disposition: inline; filename="example.jpg" Accept-Ranges: bytes ETag: "6457646542258052f767868fd686d74d" Last-Modified: Tue, 11 Jul 2017 07:27:15 GMT x-jss-storage-class: STANDARD X-Trace: 206-1499758451594-0-0-20-44-44