iOS networking（四） http异步文件上传和下载以及进度指示
本篇主要关注如何处理文件上传和下载，如何获取文件上传和下载的进度。
文件下载和进度
nodejs服务端下载图片
先改造一下我们的服务端程序，来下载一张图片，代码如下
//下载返回文件流
function download(req,res){
//写入头
var downloadFilePath = "./1.jpg";
var filename = path.basename(downloadFilePath);
var filesize = fs.readFileSync(downloadFilePath).length;
res.setHeader('Content-Disposition','attachment;filename=' + filename);//此处是关键
res.setHeader('Content-Length',filesize);
res.setHeader('Content-Type','application/octet-stream');
var fileStream = fs.createReadStream(downloadFilePath,{bufferSize:1024 * 1024});
fileStream.pipe(res,{end:true});
// res.writeHead(200, {'content-type': 'text/html'});
}
//改造一下handler方法，让url访问/download的时候进入文件下载的方法，返回文件流
handler:function(req,res){
console.log('handler');
console.log(req.url);
switch(req.url){
case '/' : get(req,res); break;
case "/download" : download(req,res); break;
}
}
iOS请求下载文件流
//http下载文件流
- (void)download{
//string 转 url编码
NSString *urlString = @"http://localhost:8001/download";
NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]]];
NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
[connection start];
}
修改下请求委托，打印出请求头和收到的data，从而看一下收到的数据大小和数据请求进度相关内容。
//接收响应
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
NSLog(@"=================didReceiveResponse=================");
NSHTTPURLResponse *resp = (NSHTTPURLResponse *)response;
NSLog(@"response:%@",resp);
}
//接收响应
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
NSLog(@"=================didReceiveData=================");
NSLog(@"data.length:%lu",(unsigned long)data.length);
}
完成请求后打印出的结果如下：
2016-02-11 21:48:50.694 network-demo[14461:1033375] =================request redirectResponse=================
2016-02-11 21:48:50.696 network-demo[14461:1033375] request:<NSURLRequest: 0x7f91ea7948d0> { URL: http://localhost:8001/download }
2016-02-11 21:48:50.706 network-demo[14461:1033375] =================didReceiveResponse=================
2016-02-11 21:48:50.706 network-demo[14461:1033375] response:<NSHTTPURLResponse: 0x7f91ea5596f0> { URL: http://localhost:8001/download } { status code: 200, headers {
Connection = "keep-alive";
"Content-Disposition" = "attachment;filename=1.jpg";
"Content-Length" = 19557;
"Content-Type" = "application/octet-stream";
Date = "Thu, 11 Feb 2016 13:48:50 GMT";
} }
2016-02-11 21:48:50.706 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 21:48:56.148 network-demo[14461:1033375] data.length:19557
2016-02-11 21:48:56.148 network-demo[14461:1033375] =================connectionDidFinishLoading=================
可以看出：服务端在resqonse头中加入了content-length信息，告知整个流的大小，不过因为图片文件本身
较小，所以并没有分包，因此didReceiveData方法只调用了一次就完成了文件传递。大家可以试着修改下服务端返回的文件，
改为一个较大点的文件来试一次，这里我改成一个稍微大一些的图片，一张我自己hhkb键盘的美图~
var downloadFilePath = "./IMG_0222.jpg"; 再试着发一次请求：
2016-02-11 22:09:14.088 network-demo[14461:1033375] =================request redirectResponse=================
2016-02-11 22:09:14.089 network-demo[14461:1033375] request:<NSURLRequest: 0x7f91ea54c5f0> { URL: http://localhost:8001/download }
2016-02-11 22:09:14.118 network-demo[14461:1033375] =================didReceiveResponse=================
2016-02-11 22:09:14.119 network-demo[14461:1033375] response:<NSHTTPURLResponse: 0x7f91ea591810> { URL: http://localhost:8001/download } { status code: 200, headers {
Connection = "keep-alive";
"Content-Disposition" = "attachment;filename=IMG_0222.jpg";
"Content-Length" = 1265302;
"Content-Type" = "application/octet-stream";
Date = "Thu, 11 Feb 2016 14:09:14 GMT";
} }
2016-02-11 22:09:14.119 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.119 network-demo[14461:1033375] data.length:65536
2016-02-11 22:09:14.120 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.120 network-demo[14461:1033375] data.length:65536
2016-02-11 22:09:14.121 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.121 network-demo[14461:1033375] data.length:65536
2016-02-11 22:09:14.122 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.122 network-demo[14461:1033375] data.length:131072
2016-02-11 22:09:14.123 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.123 network-demo[14461:1033375] data.length:132000
2016-02-11 22:09:14.123 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.124 network-demo[14461:1033375] data.length:392288
2016-02-11 22:09:14.124 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.124 network-demo[14461:1033375] data.length:65536
2016-02-11 22:09:14.124 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.125 network-demo[14461:1033375] data.length:65536
2016-02-11 22:09:14.125 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.125 network-demo[14461:1033375] data.length:65536
2016-02-11 22:09:14.125 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.125 network-demo[14461:1033375] data.length:65536
2016-02-11 22:09:14.126 network-demo[14461:1033375] =================didReceiveData=================
2016-02-11 22:09:14.126 network-demo[14461:1033375] data.length:151190
2016-02-11 22:09:14.126 network-demo[14461:1033375] =================connectionDidFinishLoading=================
可以看到didReceiveData委托被反复调用了很多次，我们可以通过 data.length:151190 和 "Content-Length" = 1265302;
就可以计算出流的下载进度。
//获取Content-Length
//[[((NSHTTPURLResponse *)response) allHeaderFields]objectForKey:@"Content-length"]
获取到完成的data后，可以直接把二进制的data转换成图片，代码如下：
UIImage *img = [UIImage imageWithData:data];
UIImageView *imageView = [[UIImageView alloc]initWithImage:img];
[imageView setFrame:CGRectMake(30, 30, 200, 200)];
[self.view addSubview:imageView];
上传文件和进度
服务端代码
服务端使用nodejs写的接受图片上传，重命名并保存文件，使用了formidable这个库完成图片获取，作为demo写的比较简单大家随意感受下。
//文件上传
function upload(req,res){
//创建上传表单
var form = new formidable.IncomingForm();
//设置编辑
form.encoding = 'utf-8';
//设置上传目录
form.uploadDir = './upload/';
form.keepExtensions = true;
//文件大小
form.maxFieldsSize = 10 * 1024 * 1024;
form.parse(req, function (err, fields, files) {
if(err) {
res.send(err);
return;
}
// console.log(fields);
console.log("=====");
// console.log(files);
// console.log(files.file.name);
var extName = /\.[^\.]+/.exec(files.file.name);
var ext = Array.isArray(extName)
? extName[0]
: '';
//重命名，以防文件重复
var avatarName = uuid() + ext;
//移动的文件目录
var newPath = form.uploadDir + avatarName;
fs.renameSync(files.file.path, newPath);
// res.send('success');
var msg = { "status":1,"msg":"succeed"}
res.write(JSON.stringify(msg));
res.end();
});
}
http文件传输协议
来说点文件上传http协议的基础，前面的demo中，我们都没有设置请求头，因为我们都使用了默认的请求头
Content-Type:application/x-www-form-urlencoded ，这个请求头就是和html中的表单上传，如果get请求则
数据在url中，如果post请求，数据默认放在请求体中。然后默认的x-www-form-urlencoded头并不能上传文件，上传文件需要
设置头为：Content-Type:multipart/form-data; boundary=YY ，boundary用于标识边界，可以自定义，使用时前面需要加上两个–，例如：”–YY”
我们在iOS上传文件时需要这样设置请求头
/** 设置请求头 */
// 请求体的长度
[request setValue:[NSString stringWithFormat:@"%zd", body.length] forHTTPHeaderField:@"Content-Length"];
// 声明这个POST请求是个文件上传
[request setValue:@"multipart/form-data; boundary=YY" forHTTPHeaderField:@"Content-Type"];
[request setHTTPMethod:@"POST"];
iOS文件上传代码
我们上传一张稍微大点的图片，直接使用NSBundle对象读取项目中的文件，然后设置请求相关的委托方法，代码如下
//http上传文件流
- (void)upload{
#define Encode(str) [str dataUsingEncoding:NSUTF8StringEncoding]
NSURL *dataurl = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"IMG_0222" ofType:@"jpg"]];
NSData *data = [NSData dataWithContentsOfURL:dataurl];
//string 转 url编码
NSString *urlString = @"http://localhost:8001/upload";
NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
/** 设置请求头 */
NSMutableData *body = [NSMutableData data];
//文件参数
// 参数开始的标志
[body appendData:Encode(@"--YY\r\n")];
// name : 指定参数名(必须跟服务器端保持一致)
// filename : 文件名
NSString *disposition = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"; filename=\"%@\"\r\n", @"file", @"1.jpg"];
[body appendData:Encode(disposition)];
NSString *type = [NSString stringWithFormat:@"Content-Type: %@\r\n", @"multipart/form-data"];
[body appendData:Encode(type)];
[body appendData:Encode(@"\r\n")];
//添加图片数据
[body appendData:data];
[body appendData:Encode(@"\r\n")];
//结束符
[body appendData:Encode(@"--YY--\r\n")];
//把body添加到request中
[request setHTTPBody:body];
/** 设置请求头 */
// 请求体的长度
[request setValue:[NSString stringWithFormat:@"%zd", body.length] forHTTPHeaderField:@"Content-Length"];
// 声明这个POST请求是个文件上传
[request setValue:@"multipart/form-data; boundary=YY" forHTTPHeaderField:@"Content-Type"];
[request setHTTPMethod:@"POST"];
NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
[connection start];
}
#pragma mark -网络请求委托
//请求失败
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
NSLog(@"=================didFailWithError=================");
NSLog(@"error:%@",error);
}
//重定向
- (nullable NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(nullable NSURLResponse *)response{
NSLog(@"=================request redirectResponse=================");
NSLog(@"request:%@",request);
return request;
}
//接收响应
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
NSLog(@"=================didReceiveResponse=================");
NSHTTPURLResponse *resp = (NSHTTPURLResponse *)response;
NSLog(@"response:%@",resp);
}
//接收响应
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
NSLog(@"=================didReceiveData=================");
// UIImage *img = [UIImage imageWithData:data];
// UIImageView *imageView = [[UIImageView alloc]initWithImage:img];
// [imageView setFrame:CGRectMake(30, 30, 200, 200)];
// [self.view addSubview:imageView];
NSLog(@"data.length:%lu",(unsigned long)data.length);
if (data) {
NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:nil];
NSLog(@"data:%@",dic);
}
}
//上传数据委托，用于显示上传进度
- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten
totalBytesWritten:(NSInteger)totalBytesWritten
totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite{
NSLog(@"=================totalBytesWritten=================");
NSLog(@"didSendBodyData:%ld,totalBytesWritten:%ld,totalBytesExpectedToWrite:%ld",(long)bytesWritten,(long)totalBytesWritten,(long)totalBytesExpectedToWrite);
NSLog(@"上传进度%ld%%",(long)(totalBytesWritten*100 / totalBytesExpectedToWrite));
}
//完成请求
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
NSLog(@"=================connectionDidFinishLoading=================");
}
大家可以看下代码，重点可以看下 upload方法，和
- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten
totalBytesWritten:(NSInteger)totalBytesWritten
这个委托，观察如何设置文件上传的请求头和请求体，如果获取上传文件的进度。
程序运行后打印的结果
服务端日志，打印请求头
{ host: 'localhost:8001',
'content-type': 'multipart/form-data; boundary=YY',
connection: 'keep-alive',
accept: '*/*',
'user-agent': 'network-demo/1 CFNetwork/758.0.2 Darwin/14.5.0',
'content-length': '1265418',
'accept-language': 'en-us',
'accept-encoding': 'gzip, deflate' }
客户端日志：
2016-02-12 13:05:07.330 network-demo[16708:1254465] =================request redirectResponse=================
2016-02-12 13:05:07.331 network-demo[16708:1254465] request:<NSURLRequest: 0x7f9fa1691240> { URL: http://localhost:8001/upload }
2016-02-12 13:05:07.339 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.339 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:32768,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.339 network-demo[16708:1254465] 上传进度2%
2016-02-12 13:05:07.339 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.339 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:65536,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.339 network-demo[16708:1254465] 上传进度5%
2016-02-12 13:05:07.340 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.340 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:98304,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.340 network-demo[16708:1254465] 上传进度7%
2016-02-12 13:05:07.340 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.340 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:131072,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.340 network-demo[16708:1254465] 上传进度10%
2016-02-12 13:05:07.340 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.341 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:163840,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.341 network-demo[16708:1254465] 上传进度12%
2016-02-12 13:05:07.341 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.341 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:196608,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.341 network-demo[16708:1254465] 上传进度15%
2016-02-12 13:05:07.341 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.341 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:229376,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.342 network-demo[16708:1254465] 上传进度18%
2016-02-12 13:05:07.342 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.342 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:262144,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.342 network-demo[16708:1254465] 上传进度20%
2016-02-12 13:05:07.342 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.342 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:294912,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.342 network-demo[16708:1254465] 上传进度23%
2016-02-12 13:05:07.343 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.343 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:327680,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.343 network-demo[16708:1254465] 上传进度25%
2016-02-12 13:05:07.343 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.343 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:360448,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.343 network-demo[16708:1254465] 上传进度28%
2016-02-12 13:05:07.343 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.343 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:393216,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.344 network-demo[16708:1254465] 上传进度31%
2016-02-12 13:05:07.344 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.344 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:425984,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.344 network-demo[16708:1254465] 上传进度33%
2016-02-12 13:05:07.354 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.354 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:458752,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.354 network-demo[16708:1254465] 上传进度36%
2016-02-12 13:05:07.354 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.354 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:491520,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.354 network-demo[16708:1254465] 上传进度38%
2016-02-12 13:05:07.354 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.354 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:524288,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.355 network-demo[16708:1254465] 上传进度41%
2016-02-12 13:05:07.355 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.355 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:557056,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.355 network-demo[16708:1254465] 上传进度44%
2016-02-12 13:05:07.355 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.355 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:589824,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.355 network-demo[16708:1254465] 上传进度46%
2016-02-12 13:05:07.356 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.356 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:622592,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.356 network-demo[16708:1254465] 上传进度49%
2016-02-12 13:05:07.356 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.356 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:655360,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.356 network-demo[16708:1254465] 上传进度51%
2016-02-12 13:05:07.356 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.357 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:688128,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.357 network-demo[16708:1254465] 上传进度54%
2016-02-12 13:05:07.357 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.357 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:720896,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.357 network-demo[16708:1254465] 上传进度56%
2016-02-12 13:05:07.357 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.357 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:753664,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.357 network-demo[16708:1254465] 上传进度59%
2016-02-12 13:05:07.358 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.358 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:786432,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.358 network-demo[16708:1254465] 上传进度62%
2016-02-12 13:05:07.358 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.358 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:819200,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.359 network-demo[16708:1254465] 上传进度64%
2016-02-12 13:05:07.359 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.359 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:851968,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.359 network-demo[16708:1254465] 上传进度67%
2016-02-12 13:05:07.359 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.359 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:884736,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.359 network-demo[16708:1254465] 上传进度69%
2016-02-12 13:05:07.359 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.360 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:917504,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.360 network-demo[16708:1254465] 上传进度72%
2016-02-12 13:05:07.360 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.360 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:950272,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.360 network-demo[16708:1254465] 上传进度75%
2016-02-12 13:05:07.360 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.360 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:983040,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.361 network-demo[16708:1254465] 上传进度77%
2016-02-12 13:05:07.374 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.375 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:1015808,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.375 network-demo[16708:1254465] 上传进度80%
2016-02-12 13:05:07.375 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.375 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:1048576,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.375 network-demo[16708:1254465] 上传进度82%
2016-02-12 13:05:07.375 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.375 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:1081344,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.375 network-demo[16708:1254465] 上传进度85%
2016-02-12 13:05:07.375 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.376 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:1114112,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.376 network-demo[16708:1254465] 上传进度88%
2016-02-12 13:05:07.376 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.376 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:1146880,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.376 network-demo[16708:1254465] 上传进度90%
2016-02-12 13:05:07.376 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.376 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:1179648,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.376 network-demo[16708:1254465] 上传进度93%
2016-02-12 13:05:07.377 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.377 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:1212416,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.377 network-demo[16708:1254465] 上传进度95%
2016-02-12 13:05:07.377 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.377 network-demo[16708:1254465] didSendBodyData:32768,totalBytesWritten:1245184,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.377 network-demo[16708:1254465] 上传进度98%
2016-02-12 13:05:07.377 network-demo[16708:1254465] =================totalBytesWritten=================
2016-02-12 13:05:07.377 network-demo[16708:1254465] didSendBodyData:20234,totalBytesWritten:1265418,totalBytesExpectedToWrite:1265418
2016-02-12 13:05:07.378 network-demo[16708:1254465] 上传进度100%
2016-02-12 13:05:07.404 network-demo[16708:1254465] =================didReceiveResponse=================
2016-02-12 13:05:07.405 network-demo[16708:1254465] response:<NSHTTPURLResponse: 0x7f9fa16af610> { URL: http://localhost:8001/upload } { status code: 200, headers {
Connection = "keep-alive";
Date = "Fri, 12 Feb 2016 05:05:07 GMT";
"Transfer-Encoding" = Identity;
} }
2016-02-12 13:05:07.405 network-demo[16708:1254465] =================didReceiveData=================
2016-02-12 13:05:07.405 network-demo[16708:1254465] data.length:28
2016-02-12 13:05:07.405 network-demo[16708:1254465] data:{
msg = succeed;
status = 1;
}
2016-02-12 13:05:07.405 network-demo[16708:1254465] =================connectionDidFinishLoading=================
大家可以看出如何读取文件上传的进度了。
总结异步http请求
使用异步http请求代码量复杂，但是有许多其他方式达不到的优点
- 使用文件流上传和下载，节省内存
- 文件上传和下载有进度提示
- 可以处理url验证
- 可以取消在请求过程中取消请求（ 使用
[connection cancel]方法）
例如在demo中注释的一段代码：
- (void)connection:(NSURLConnection *)connection didSendBodyData:(NSInteger)bytesWritten
totalBytesWritten:(NSInteger)totalBytesWritten
totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite{
...
...
//测试取消上传
//if((totalBytesWritten*100 / totalBytesExpectedToWrite) > 50){[connection cancel];}
}
测试当上传进度到50%的时候，取消文件上传。
请用大一点的图片进行测试，因为这段代码是有bug的，当文件太小不会进入这个委托方法。
demo
感谢收看，如果对大家有帮助，请github上follow和star，本文发布在刘彦玮的技术博客，转载请注明出处
参考阅读
- iOS原生文件上传
- iOS开发网络篇—文件的上传
- 自己动手写一个 iOS 网络请求库（四）——快速文件上传
- Multipart/form-data POST文件上传详解
- nodejs 文件上传/下载功能实现
- Node.js：文件上传简单demo
