以下是一個請求報文與相應的回覆報文的例子:
GET /image/index_r4_c1.jpg HTTP/1.1 Accept: */* Referer: http://192.168.3.120:8080 Accept-Language: zh-cn Accept-Encoding: gzip, deflate User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; .NET CLR 1.0.3705) Host: 192.168.3.120:8080 Connection: Keep-Alive HTTP/1.1 200 OK Server: Microsoft-IIS/5.0 Date: Tue, 24 Jun 2003 05:39:40 GMT Content-Type: image/jpeg Accept-Ranges: bytes Last-Modified: Thu, 23 May 2002 03:05:40 GMT ETag: "bec48eb862c21:934" Content-Length: 2827 …. |
下面我們就來說說"斷點續傳",顧名思義,斷點續傳就是在上一次下載時斷開的位置開始繼續下載。
在HTTP協議中,可以在請求報文頭中加入Range段,來表示客戶機希望從何處繼續下載。
比如說從第1024字節開始下載,請求報文如下:
GET /image/index_r4_c1.jpg HTTP/1.1 Accept: */* Referer: http://192.168.3.120:8080 Accept-Language: zh-cn Accept-Encoding: gzip, deflate User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; .NET CLR 1.0.3705) Host: 192.168.3.120:8080 Range:bytes=1024- Connection: Keep-Alive |