iOS开发之网络编程--使用NSURLConnection实现大文件断点续传下载+使用输出流代替文件句柄

  1 #import "ViewController.h"
  2 
  3 @interface ViewController ()
  4 @property (nonatomic ,assign)NSInteger totalSzie;
  5 @property (nonatomic ,assign)NSInteger currentSzie;
  6 @property (nonatomic, strong) NSString *fileName;
  7 /** 文件的路径*/
  8 @property (nonatomic ,strong) NSString *fullPath;
  9 /** 请求对象*/
 10 @property (nonatomic ,strong)NSURLConnection *connect;
 11 /** 输出流*/
 12 @property (nonatomic ,strong)NSOutputStream *stream;
 13 @property (weak, nonatomic) IBOutlet UIProgressView *progressView;
 14 @end
 15 
 16 @implementation ViewController
 17 #pragma mark ----------------------
 18 #pragma mark Events
 19 - (IBAction)downloadBtnClick:(id)sender
 20 {
 21     
 22 //    [[NSFileManager defaultManager] removeItemAtPath:self.fullPath error:nil];
 23     
 24     [self download];
 25 }
 26 - (IBAction)cancelBtnClick:(id)sender
 27 {
 28     //取消网络请求
 29     [self.connect cancel];
 30 }
 31 
 32 #pragma mark ----------------------
 33 #pragma mark Methods
 34 -(void)download
 35 {
 36     NSLog(@"------");
 37     //1.确定url
 38     NSURL *url =[NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"];
 39     
 40     //2.创建请求对象
 41     NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
 42     
 43     //设置请求头信息,说明只需要请求该资源的一部分数据
 44     /*
 45      bytes=0-1000 表示下载0~1000的数据
 46      bytes=0-     表示从0开始下载直到下载完毕
 47      bytes=100-   表示从0开始下载直到下载完毕
 48      */
 49     NSString *range = [NSString stringWithFormat:@"bytes=%zd-",self.currentSzie];
 50     [request setValue:range forHTTPHeaderField:@"Range"];
 51     NSLog(@"%@",range);
 52     
 53     //3.发送异步请求
 54     self.connect = [NSURLConnection connectionWithRequest:request delegate:self];
 55 }
 56 
 57 #pragma mark ----------------------
 58 #pragma mark NSURLConnectionDataDelegate
 59 -(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
 60 {
 61     NSLog(@"--didReceiveResponse-");
 62     
 63     //判断是否已经下载过了
 64     if (self.currentSzie >0) {
 65         return;
 66     }
 67     
 68     //0.获得文件的总大小
 69     //expectedContentLength是本次请求的数据的大小,并不是整个
 70     self.totalSzie = response.expectedContentLength;
 71     
 72     //1.得到文件的名称
 73     self.fileName = response.suggestedFilename;
 74     
 75     //2.获得文件的全路径
 76     //caches
 77     NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
 78     
 79     NSString *fullPath = [caches stringByAppendingPathComponent:self.fileName];
 80     self.fullPath = fullPath;
 81     
 82     //3.创建输出流
 83     /*
 84      第一个参数: 写入数据的地址
 85      第二个参数: 表示要不要追加 断点续传肯定要追加
 86      */
 87     NSOutputStream *stream = [[NSOutputStream alloc]initToFileAtPath:fullPath append:YES];
 88     self.stream = stream;
 89     
 90     //4.打开数据流
 91     // 如果文件不存在,那么会自动创建一个空的文件
 92     [self.stream open];
 93 }
 94 
 95 -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
 96 {
 97     //写数据
 98     /*
 99      第一个参数:要写的数据
100      第二个参数:数据的长度
101      */
102     [self.stream write:data.bytes maxLength:data.length];
103     
104     
105     //3.累加当前下载的数据大小
106     self.currentSzie +=data.length;
107     
108     //4.计算文件的下载进度
109     NSLog(@"%f",1.0 *  self.currentSzie / self.totalSzie);
110     
111     self.progressView.progress = 1.0 *  self.currentSzie / self.totalSzie;
112 }
113 
114 -(void)connectionDidFinishLoading:(NSURLConnection *)connection
115 {
116     NSLog(@"%@",self.fullPath);
117     
118     //1.关闭输出流
119     [self.stream close];
120     
121     //2.清空指针
122     self.stream = nil;
123 }
124 
125 -(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
126 {
127 }
128 
129 @end