文件下载 NSURLConnection——文件下载与上传

一、文件下载 

重点：NSURLConnection的代理方法不是NSURLConnectionDelegate,而是NSURLConnectionDataDelegate

1.下载小文件，只适合几百k,1、2M的文件

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//1.设置网址 //2.加载请求 //3.设置代理 //4.实现代理方法下载文件  NSURL *url = [NSURL URLWithString:@"https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1492791082124&di=fc642407b4ec19430334653a9b873cff&imgtype=0&src=http%3A%2F%2Fi0.szhomeimg.com%2FUploadFiles%2FBBS%2F2006%2F10%2F24%2F27567833_1950.442.jpg"];   NSURLRequest *request = [NSURLRequest requestWithURL:url]; [[NSURLConnection alloc] initWithRequest:request delegate:self]; 代理实现 #pragma mark ---NSURLConnectionDelegate - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{     NSLog(@"下载失败%@",error); } //下载响应 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{ //获取文件大小     _totalSize = response.expectedContentLength; } //下载数据 - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{     //拼接数据     [_mudata appendData:data];     //获取当前进度     NSLog(@"%f",1.0*_mudata.length/_totalSize); } //下载完成 - (void)connectionDidFinishLoading:(NSURLConnection *)connection{           NSString *fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"1.jpg"];     [_mudata writeToFile:fullPath atomically:YES]; }

　　缺点：[_mudata appendData:data]，会使内存暴涨，而且下载完毕后内存不会下降

2.通过句柄来下载大文件

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#pragma mark ---------------------- #pragma mark NSURLConnectionDataDelegate -(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {     NSLog(@"didReceiveResponse");           //1.得到文件的总大小(本次请求的文件数据的总大小)     self.totalSize = response.expectedContentLength;           //2.写数据到沙盒中     self.fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject]stringByAppendingPathComponent:@"123.mp4"];           //3.创建一个空的文件     [[NSFileManager defaultManager] createFileAtPath:self.fullPath contents:nil attributes:nil];           //4.创建文件句柄(指针)     self.handle = [NSFileHandle fileHandleForWritingAtPath:self.fullPath]; }   -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {     //1.移动文件句柄到数据的末尾     [self.handle seekToEndOfFile];           //2.写数据     [self.handle writeData:data];           //3.获得进度     self.currentSize += data.length;           //进度=已经下载/文件的总大小     NSLog(@"%f",1.0 *  self.currentSize/self.totalSize);     self.progressView.progress = 1.0 *  self.currentSize/self.totalSize;     //NSLog(@"%@",self.fullPath); } -(void)connectionDidFinishLoading:(NSURLConnection *)connection {     //1.关闭文件句柄     [self.handle closeFile];     self.handle = nil;     NSLog(@"connectionDidFinishLoading");     NSLog(@"%@",self.fullPath); }

　3.通过断点续传来下载大文件(初级版)

设置请求头，如果文件存在就继续下载

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//与上面不同的是请求头增加了Range     NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];     NSString *Range = [NSString stringWithFormat:@"bytes=%zd",_currentSize];     [request setValue:Range forHTTPHeaderField:@"Range"]; //下面判断文件是否存在不同，如果大于0就返回，不好的地方，删除了文件就不能再下载，待之后完善 //接受响应 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{     NSLog(@"%@",response);     NSLog(@"%@",response.MIMEType);     //如果放在最前面，文件大小就需要加上当前文件的大小     //如果有下载返回，只适用于当前     //设置沙盒文件     //创建空文件用NSFileManager     //句柄指向该文件     _totalSize = response.expectedContentLength+_currentSize;     if(_currentSize > 0){         NSLog(@"文件已经下载");         return;     }     _fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory,NSUserDomainMask, YES)lastObject] stringByAppendingPathComponent:@"downFile.jpg"];     //contents内容为空，     [[NSFileManager defaultManager] createFileAtPath:_fullPath contents:nil attributes:nil];     _fileHandle = [NSFileHandle fileHandleForWritingAtPath:_fullPath];      } //接受数据 - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{     //将句柄移动到文件末尾     //通过句柄写入数据     //获取文件进度     if (_currentSize <=1) {         _currentSize += data.length;         NSLog(@"%f",1.0*_currentSize/_totalSize);     }     [_fileHandle seekToEndOfFile];     [_fileHandle writeData:data];     _progressView.progress = 1.0*_currentSize/_totalSize; }

　　　缺点：删除了以后不能重新下载　　

 4.文件上传，NSURLConnection上传比较比较奇葩

 

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//文件上传 - (void)fileUpload{     //1.确认请求路径     NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/upload"];     //2.创建可变请求     NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];     //3.设置请求方法     request.HTTPMethod = @"POST";     //4.设置请求头信息,Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryjv0UfA04ED44AhWx     [request setValue:[NSString stringWithFormat:@"multipart/form-data; boundary=%@",Kboundary] forHTTPHeaderField:@"Content-Type"];           //5.拼接请求体参数     NSMutableData *fileData = [NSMutableData data];     /*      --分隔符      Content-Disposition: form-data; name="file"; filename="Snip20160225_341.png"      Content-Type: image/png(MIMEType:大类型/小类型)      空行      文件参数      */     [fileData appendData:[[NSString stringWithFormat:@"--%@",Kboundary] dataUsingEncoding:NSUTF8StringEncoding]];     [fileData appendData:KNewLine];     //name:file 服务器规定的参数     //filename:Snip20160225_341.png 文件保存到服务器上面的名称     //Content-Type:文件的类型     [fileData appendData:[@"Content-Disposition: form-data; name=\"file\"; filename=\"Snip20170424_7.png\"" dataUsingEncoding:NSUTF8StringEncoding]];     [fileData appendData:KNewLine];     [fileData appendData:[@"Content-Type: image/png" dataUsingEncoding:NSUTF8StringEncoding]];     [fileData appendData:KNewLine];     [fileData appendData:KNewLine];           //image图片     UIImage *image = [UIImage imageNamed:@"Snip20170424_7"];     //UIImage --->NSData     NSData *imageData = UIImagePNGRepresentation(image);     [fileData appendData:imageData];     [fileData appendData:KNewLine];     //非文件参数     //分隔符，     //非文件参数     /*      --分隔符      Content-Disposition: form-data; name="username"      空行      123456      */     [fileData appendData:[[NSString stringWithFormat:@"--%@",Kboundary] dataUsingEncoding:NSUTF8StringEncoding]];     [fileData appendData:KNewLine];     [fileData appendData:[@"Content-Disposition: form-data; name=\"username\"" dataUsingEncoding:NSUTF8StringEncoding]];     [fileData appendData:KNewLine];     [fileData appendData:KNewLine];     [fileData appendData:[@"123456" dataUsingEncoding:NSUTF8StringEncoding]];     [fileData appendData:KNewLine];     //结尾标识符     /*      --分隔符--      */     [fileData appendData:[[NSString stringWithFormat:@"--%@--",Kboundary] dataUsingEncoding:NSUTF8StringEncoding]];           //6.设置请求体，请求体二进制数据     request.HTTPBody = fileData;     //发送请求     [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {         //解析数据         NSLog(@"%@",[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]);     }]; }