进行Chunked编码传输的HTTP Response会在消息头部设置:
Transfer-Encoding: chunked
表示Content Body将用Chunked编码传输内容。
Chunked编码使用若干个Chunk串连而成,由一个标明长度为0的chunk标示结束。每个Chunk分为头部和正文两部分,头部内容指定下一段正文的字符总数(十六进制的数字)和数量单位(一般不写),正文部分就是指定长度的实际内容,两部分之间用回车换行(CRLF)隔开。在最后一个长度为0的Chunk中的内容是称为footer的内容,是一些附加的Header信息(通常可以直接忽略)。具体的Chunk编码格式如下:
Chunked-Body = *chunk
"0" CRLF
footer
CRLF
chunk = chunk-size [ chunk-ext ] CRLF
chunk-da<wbr>ta CRLF</wbr>
hex-no-zero = <HEX excluding "0">
chunk-size = hex-no-zero *HEX
chunk-ext = *( ";" chunk-ext-name [ "=" chunk-ext-value ] )
chunk-ext-name = token
chunk-ext-val = token | quoted-string
chunk-da<wbr>ta = chunk-size(OCTET)</wbr>
footer = *entity-header
RFC文档中的Chunked解码过程如下:
length := 0
read chunk-size, chunk-ext (if any) and CRLF
while (chunk-size > 0) {
read chunk-da<wbr>ta and CRLF<br> append chunk-da<wbr>ta to entity-body<br> length := length + chunk-size<br> read chunk-size and CRLF<br> }<br> read entity-header<br> while (entity-header not empty) {<br> append entity-header to existing header fields<br> read entity-header<br> }<br> Content-Length := length<br> Remove "chunked" from Transfer-Encoding</wbr></wbr>
最后提供一段PHP版本的chunked解码代码:
$chunk_size=(integer)hexdec(fgets($socket_fd,4096) );
while(!feof($socket_fd)&&$chunk_size>0) {
$bodyContent.=fread($socket_fd,$chunk_size);
fread($socket_fd,2);//skip \r\n
$chunk_size=(integer)hexdec(fgets($socket_fd,4096) );
}
要解决服务器不返回Transfer-Encoding:chunked,在客户端请求的时候可以使用http 1.0的协议。