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【IOS学习】http异步文件上传和下载及进度指示

程序员文章站 2022-06-02 22:20:26
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(...

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 = @"https://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: { url: https://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: { url: https://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: { url: https://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: { url: https://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 = @"https://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: { url: https://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: { url: https://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。

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