使用以下代码进行POST请求：
string body = "Hello World";
byte[] bytes = Encoding.ASCII.GetBytes(body);
WebRequest request = WebRequest.Create("http://internalurl");
request.Method = "POST";
request.ContentLength = bytes.Length;
我将内容长度设置为POST的字节数。那么对于GET请求，正确的ContentLength是什么？
由于通常在进行GET请求时不会发送任何附加数据，因此不应发送头部Content-Length。
仅当您发送消息正文时才应包含头部Content-Length，而所讨论的头部的值始终是该字段的长度，以(OCTETs)字节为单位。
(RFC2616) 14.13 Content-Length
Content-Length实体头字段指示发送给接收者的实体正文大小，以十进制OCTETs字节数表示。对于HEAD方法的情况下，它指示将要发送的实体正文的大小，如果该请求是GET，则也是如此。
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除非第4.4节中的规则禁止使用该字段，否则应用程序应使用此字段来指示消息正文的传输长度。
我所知，当进行GET请求时包含message-body被认为是不好的做法，但是在阅读HTTP RFC2616时，我没有看到任何规定GET请求不能包含message-body。
尽管我会假设大多数Web服务器今天不会回复您想要的回复，如果您发送数据并期望在该情况下对其进行解析和处理，则包含message-body。
(RFC2616) 4.3 Message Body
The message-body (if any) of an HTTP message is used to carry the entity-body associated with the request or response. The message-body differs from the entity-body only when a transfer-coding has been applied, as indicated by the Transfer-Encoding header field (section 14.41).
message-body = entity-body | <entity-body encoded as per Transfer-Encoding>Transfer-Encoding MUST be used to indicate any transfer-codings applied by an application to ensure safe and proper transfer of the message. Transfer-Encoding is a property of the message, not of the entity, and thus MAY be added or removed by any application along the request/response chain. (However, section 3.6 places restrictions on when certain transfer-codings may be used.)
The rules for when a message-body is allowed in a message differ for requests and responses.
The presence of a message-body in a request is signaled by the inclusion of a Content-Length or Transfer-Encoding header field in the request's message-headers.
A message-body MUST NOT be included in a request if the specification of the request method (section 5.1.1) does not allow sending an entity-body in requests.
A server SHOULD read and forward a message-body on any request; if the request method does not include defined semantics for an entity-body, then the message-body SHOULD be ignored when handling the request.