HTTP POST查询如何计算内容长度

Question

I am making a HTTP POST query to a server and I am creating the post body manually. I think I am making some mistake with the content-length header because on the server side when I get the http response at the beginning I see the headers with http response 200 and then when in my php script I print the post parameters and file names I get the correct values but together with some junk bytes. Here is the body of my http post:

StringBuffer str = new StringBuffer();
str.append("POST /tst/query.php HTTP/1.1\r\n"
        + "Host: myhost.com\r\n"
        + "User-Agent: sampleAgent\r\n"
        + "Content-type: multipart/form-data, boundary=AaB03x\r\n" 
        + "Content-Length: 172\r\n\r\n"
        + "--AaB03x\r\n"
        + "content-disposition: form-data; name=\"asd\"\r\n\r\n123\r\n--AaB03x\r\n"
        + "content-disposition: form-data; name=\"pics\"; filename=\"file1.txt\"\r\n"
        + "Content-Type: text/plain\r\n\r\n555\r\n"
        + "--AaB03x--"
);

Here is the output from the server(ignore [0.0] - it comes from the console where I print the result)

[0.0] HTTP/1.1 200 OK

[0.0] Date: Sat, 10 Dec 2011 11:53:11 GMT

[0.0] Server: Apache

[0.0] Transfer-Encoding: chunked

[0.0] Content-Type: text/html

[0.0] 

[0.0] 6

[0.0] Array
[0.0] 

[0.0] 2

[0.0] (
[0.0] 

[0.0] 1

[0.0]  

[0.0] 1

[0.0]  

[0.0] 1

[0.0]  

[0.0] 1

[0.0]  

[0.0] 1

[0.0] [

[0.0] 3

[0.0] asd

[0.0] 5

[0.0] ] => 

3
123
1
2
)
0

And the php script on the server which is as simple as you can think of:

<?php 
    print_r($_POST) ;
?>

Answer 1

From the HTTP RFC ( RFC2626, 14.3 )

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.

In other words you should count the number of bytes ( octets ), therefor \\r\\n should be considered to be 2 octets/bytes.

Answer 2

String boundary = "AaB03x";
String body = "--" + boundary + "\r\n"
            + "Content-Disposition: form-data; name=\"asd\"\r\n"
            + "\r\n"
            + "123\r\n"
            + "--" + boundary + "\r\n"
            + "Content-Disposition: form-data; name=\"pics\"; filename=\"file1.txt\"\r\n"
            + "Content-Type: text/plain\r\n"
            + "\r\n"
            + "555\r\n"
            + "--" + boundary + "--";

StringBuffer str = new StringBuffer();
str.append("POST /tst/query.php HTTP/1.1\r\n"
         + "Host: myhost.com\r\n"
         + "User-Agent: sampleAgent\r\n"
         + "Content-type: multipart/form-data, boundary=\"" + boundary + "\"\r\n" 
         + "Content-Length: " + body.length() + "\r\n"
         + "\r\n"
         + body
);

...I would say is the way it should be done

Answer 3

A lot has changed since this question was posted. Many of the modern HTTP/REST frameworks and API's will automatically handle Content-Length and other calculations.

My experience is that the Content-Length must be byte-specific, and must be calculated at the time the request is being made, since the data will likely be dynamic and change between requests.

The headers can impact the body, so take that into account as well. For instance, the Content-Type header will affect how the payload is encoded. If the body is being sent application/x-www-form-urlencoded , the size of the body will be quite different then a request in which it is encoded and sent as multipart/form-data .

Aside from that, the calculation of the payload length should be fairly simple. As Filip Roséen indicated, any line/control characters (\n \r) must also be included in the calculation.