响应预期内容长度返回 -1

问题描述

您好，当我从 Web 服务加载数据时，我需要创建一个 progressView.

Hello i need to create a progressView when i load data from my webservice.

实际上，expectedContentLength 总是返回 -1.

Actually the expectedContentLength alway return -1.

看了很多类似的问题后，看起来我的网络服务从未发送过 Content-Length:.

After look lots of similary problem it looks like my webservice never send the Content-Length:.

然后我用 CURL 检查，结果如下:

Then i check with CURL and here is the result :

< HTTP/1.1 200 OK
< Date: Thu, 21 Jun 2012 10:04:39 GMT
< Server: Apache/2.2.16 (Debian)
< X-Powered-By: PHP/5.3.3-7+squeeze9
< cache-control: no-cache
< Vary: Accept-Encoding
< Content-Type: text/html; charset=UTF-8
< Content-Length: 3239  
< Connection: Keep-Alive
< Set-Cookie: PHPSESSID=u4o4i9dofdgnkfmtnf163635j6; path=/

这是我捕捉长度的代码

long long expectDataSize;
long long currentDataSize;

....

 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response
{
    NSLog(@"expect content length %lld", [response expectedContentLength]);
    expectDataSize = [response expectedContentLength];
    currentDataSize = 0;
}

有人已经看到这个问题了吗?

Anyone have already see this problem ?

推荐答案

好的，我自己解决了，这是我真正的问题和解决方案:

Ok i've fix it myself here is my real problem and a solution :

当我用 Curl 询问时，我可以得到长度没问题.

When i ask with Curl i can get the length no problem.

但是当我使用 NSurlConnection 时

But when i use NSurlConnection

NSURLConnection *c = [[NSURLConnection alloc] initWithRequest:req delegate:self];

响应将用Gzip"压缩(不要问我为什么).如果响应是用 Gzip 编码的，则不可能知道长度，然后expectedContentLength"返回-1.[response allHeaderFields] 中没有Content-Length".

The response will be compress with "Gzip" (don't ask me why). And if the response is encode with Gzip it's impossible to know the length, then "expectedContentLength" return -1. And "Content-Length" is absent from [response allHeaderFields].

如果你真的想获得长度，你可以简单地强制不要像这样使用 Gzip:

If you really want to get the length you can simply force to not use Gzip like this :

[req setValue:@"" forHTTPHeaderField:@"Accept-Encoding"];

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