一个八位是8位。Content-length是消息体所代表的字节数。

根据说明书:

The Content-Length entity-header field indicates the size of the entity-body, in decimal number of OCTETs, sent to the recipient or, in the case of the HEAD method, the size of the entity-body that would have been sent had the request been a GET. Content-Length = "Content-Length" ":" 1*DIGIT An example is Content-Length: 3495 Applications SHOULD use this field to indicate the transfer-length of the message-body, unless this is prohibited by the rules in section 4.4. Any Content-Length greater than or equal to zero is a valid value. Section 4.4 describes how to determine the length of a message-body if a Content-Length is not given. Note that the meaning of this field is significantly different from the corresponding definition in MIME, where it is an optional field used within the "message/external-body" content-type. In HTTP, it SHOULD be sent whenever the message's length can be determined prior to being transferred, unless this is prohibited by the rules in section 4.4.

它是请求或响应体中数据的字节数。主体是出现在标题下面空行之后的部分。

Content-Length报头是一个数字，表示HTTP正文的确切字节长度。HTTP主体在开始行和报头之后的第一个空行之后立即开始。

通常，Content-Length报头用于HTTP 1.1，以便接收方知道当前响应*何时结束，这样连接就可以用于另一个请求。

*……或请求，在请求方法有一个主体的情况下，如POST, PUT或PATCH

或者，可以省略Content-Length头，使用分块的Transfer-Encoding头。

如果Content-Length和Transfer-Encoding头都缺失，则在响应的末尾必须关闭连接。

以下资源是我在学习HTTP时发现的非常有用的指南:

HTTP变得非常简单。

从本页

The most common use of POST, by far, is to submit HTML form data to CGI scripts. In this case, the Content-Type: header is usually application/x-www-form-urlencoded, and the Content-Length: header gives the length of the URL-encoded form data (here's a note on URL-encoding). The CGI script receives the message body through STDIN, and decodes it. Here's a typical form submission, using POST: POST /path/script.cgi HTTP/1.0 From: frog@jmarshall.com User-Agent: HTTPTool/1.0 Content-Type: application/x-www-form-urlencoded Content-Length: 32

从这里开始:

The Content-Length entity-header field indicates the size of the entity-body, in decimal number of OCTETs, sent to the recipient or, in the case of the HEAD method, the size of the entity-body that would have been sent had the request been a GET. Content-Length = "Content-Length" ":" 1*DIGIT An example is Content-Length: 3495 Applications SHOULD use this field to indicate the transfer-length of the message-body, unless this is prohibited by the rules in section 4.4. Any Content-Length greater than or equal to zero is a valid value. Section 4.4 describes how to determine the length of a message-body if a Content-Length is not given. Note that the meaning of this field is significantly different from the corresponding definition in MIME, where it is an optional field used within the "message/external-body" content-type. In HTTP, it SHOULD be sent whenever the message's length can be determined prior to being transferred, unless this is prohibited by the rules in section 4.4.

我的解释是，这意味着“导线上”的长度，即“编码”内容的长度