关于HTTP协议Range

[忘不了的石楠花]

为啥我在请求头里面设置了Range，但是响应还是把

- (void)start {
    NSURL *url = [NSURL URLWithString:self.sourceUrl];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url];
    //实现暂停功能就是把每次下载的数据量纪录下来，然后通过这些来设置下次下载的请求头
    NSString *value = [NSString stringWithFormat:@"bytes=%ld-%ld", self.startLocation+ self.currentLength, self.endLocation + 100];
    [request setValue:value forHTTPHeaderField:@"Range"];
    NSLog(@"请求头:%@",request.allHTTPHeaderFields);
    self.connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
}

- (void)pause {
    [self.connection cancel];
    self.connection = nil;
}

- (void)end {
    [self pause];
}

- (NSFileHandle *)fileHandle {
    if (!_fileHandle) {
        //调用这个方法，参数路径必须是实际存在的，否则返回一个空文件句柄
        _fileHandle = [NSFileHandle fileHandleForWritingAtPath:self.storePath];
    }
    return _fileHandle;
}

#pragma mark- NSURLConnection常用的代理方法
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    NSLog(@"连接服务器成功");
    NSLog(@"－－－－－respose:%@",response);//这里可以看到服务器给你的所有反馈,挺有用
    //每次连接到服务器一次（下载一次），就重新声明一个data来存储数据
    self.tempData = [[NSMutableData alloc]init];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    NSLog(@"接收到数据");//调用多次，每次接受部分数据
    [self.tempData appendData:data];
}


- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    NSLog(@"这次下载所有的数据已经下载完毕");
    [self.fileHandle writeData:self.tempData];
    [self.fileHandle closeFile];
    self.fileHandle = nil;
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"%s",__FUNCTION__);
}

打印出来是这样的：
2016-03-09 14:15:19.968 Downloader[40691:2935301] 请求头:{
Range = "bytes=0-100";
}
2016-03-09 14:15:20.193 Downloader[40691:2935301] 连接服务器成功
2016-03-09 14:15:20.193 Downloader[40691:2935301] －－－－－respose:<NSHTTPURLResponse: 0x7f96a1e3ee80> { URL: https://dn-nickey.qbox.me/124668.jpg } { status code: 200, headers {
"Accept-Ranges" = bytes;
"Access-Control-Allow-Origin" = "*";
"Access-Control-Expose-Headers" = "X-Log, X-Reqid";
"Access-Control-Max-Age" = 2592000;
"Cache-Control" = "public, max-age=31536000";
Connection = "keep-alive";
"Content-Disposition" = "inline; filename=\"124668.jpg\"";
"Content-Length" = 349812;
"Content-Transfer-Encoding" = binary;
"Content-Type" = "image/jpeg";
Date = "Wed, 09 Mar 2016 03:16:00 GMT";
Etag = "\"FrgKUK4hw_c9DDc6tq2bDghLrE7F\"";
"Last-Modified" = "Fri, 30 Oct 2015 03:36:19 GMT";
Server = "nginx/1.4.4";
"X-Log" = "mc.g;IO:3";
"X-Qiniu-Zone" = 0;
"X-Reqid" = xngAAHWdkj99DjoU;
"X-Via" = "1.1 wf96:88 (Cdn Cache Server V2.0), 1.1 chongqingwangtong13:5 (Cdn Cache Server V2.0)";
} }
2016-03-09 14:15:20.193 Downloader[40691:2935301] 接收到数据
2016-03-09 14:15:20.194 Downloader[40691:2935301] 这次下载所有的数据已经下载完毕
2016-03-09 14:15:53.999 Downloader[40691:2935301] 我这里获取到的data:<UIImage: 0x7f96a1d77290>, {1440, 1280}

[ravatar0423]

你的代码没有问题，我本地测试结果如下:

2016-03-12 14:02:52.924 DownloadRange[15134:5949962] 请求头:{
    Range = "bytes=0-100";
}
2016-03-12 14:02:53.294 DownloadRange[15134:5949962] 连接服务器成功
2016-03-12 14:02:53.295 DownloadRange[15134:5949962] －－－－－respose:<NSHTTPURLResponse: 0x7fafbac027e0> { URL: https://dn-nickey.qbox.me/124668.jpg } { status code: 206, headers {
    "Accept-Ranges" = bytes;
    "Access-Control-Allow-Origin" = "*";
    "Access-Control-Expose-Headers" = "X-Log, X-Reqid";
    "Access-Control-Max-Age" = 2592000;
    "Cache-Control" = "public, max-age=31536000";
    Connection = "keep-alive";
    "Content-Disposition" = "inline; filename=\"124668.jpg\"";
    "Content-Length" = 101;
    "Content-Range" = "bytes 0-100/349812";
    "Content-Transfer-Encoding" = binary;
    "Content-Type" = "image/jpeg";
    Date = "Sat, 12 Mar 2016 06:02:53 GMT";
    Etag = "\"FrgKUK4hw_c9DDc6tq2bDghLrE7F\"";
    "Last-Modified" = "Fri, 30 Oct 2015 03:36:19 GMT";
    Server = "nginx/1.4.4";
    "X-Log" = "mc.g;IO:2";
    "X-Qiniu-Zone" = 0;
    "X-Reqid" = jDAAAGJpXf6BAjsU;
    "X-Via" = "1.1 jx129:88 (Cdn Cache Server V2.0), 1.1 xfzh13:1 (Cdn Cache Server V2.0)";
} }
2016-03-12 14:02:53.295 DownloadRange[15134:5949962] 接收到数据
2016-03-12 14:02:53.296 DownloadRange[15134:5949962] 这次下载所有的数据已经下载完毕

[忘不了的石楠花]

最近在做多点下载和断点续传。如果本地有缓存肯定按照你说的来做，但是对于大的文件初次下载的时候，肯定多点速度更快。

[忘不了的石楠花]

谢谢你的回复，问题是缓存的问题。我是之前全部下载了，后来转成1-100的，因为缓存的问题，系统里面还是保留了上次的数据。 如果你以后遇到类似的问题可以把start方法里面request的定义换成这样NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:self.sourceUrl] cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:100];每次把不计缓存就好了。

[ravatar0423]

恩 设置缓存timeout，可以解决你的问题； 不过我有一个疑问:既然本地缓存了, 如果你能拿到全部数据，不是更好吗？如果非要根据Range取数据，那就自己根据偏移读取就好了；速度更快，更省流量