iOS开发 -------- AFNetworking实现简单的断点下载

  1 //
  2 //  ViewController.m
  3 //  AFNetworking实现断点下载
  4 //
  5 //  Created by lovestarfish on 15/11/15.
  6 //  Copyright © 2015年 大爱海星星. All rights reserved.
  7 //
  8 #define kURL @"http://61.163.117.26/wvideo.spriteapp.cn/video/2015/0714/55a4be6ab563a_wpd.mp4?wsiphost=local"
  9 #import "ViewController.h"
 10 #import "AFNetworking.h"
 11 
 12 @interface ViewController ()
 13 
 14 @property (weak, nonatomic) IBOutlet UILabel *progressLabel;
 15 @property (weak, nonatomic) IBOutlet UIProgressView *progressView;
 16 @property (nonatomic,strong) AFHTTPRequestOperation *operation;
 17 
 18 - (IBAction)start:(UIButton *)sender;
 19 
 20 @end
 21 
 22 @implementation ViewController
 23 
 24 - (void)viewDidLoad {
 25     [super viewDidLoad];
 26     // 获取保存下载进度的缓存文件
 27     NSString *txtTempPath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"mvTemp/mv.txt"];
 28     NSLog(@"%@",txtTempPath);
 29     NSFileManager *fileManager = [NSFileManager defaultManager];
 30     // 判断文件夹里面有没有之前的缓存文件
 31     if ([fileManager fileExistsAtPath:txtTempPath]) {
 32         // 有的话继续之前的下载进度下载
 33         self.progressView.progress = [[NSString stringWithContentsOfFile:txtTempPath encoding:NSUTF8StringEncoding error:nil] floatValue];
 34     } else {
 35         // 没有的话进度从0开始
 36         self.progressView.progress = 0;
 37     }
 38     
 39     // 设置显示进度的label内容
 40     self.progressLabel.text = [NSString stringWithFormat:@"%.2f%%",self.progressView.progress * 100];
 41     
 42     NSLog(@"%@",NSHomeDirectory());
 43 }
 44 
 45 /**
 46  *  开始下载
 47  */
 48 - (IBAction)start:(UIButton *)sender {
 49     if ([sender.currentTitle isEqualToString:@"开始下载"]) {
 50         // 如果已经开始下载,将按钮标题置为"暂停下载"
 51         [sender setTitle:@"暂停下载" forState:UIControlStateNormal];
 52         // 下载的url
 53         NSURL *url = [NSURL URLWithString:kURL];
 54         // 获取cache文件夹
 55         NSString *cachePath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];
 56         NSFileManager *fileManager = [NSFileManager defaultManager];
 57         // 在cache文件夹创建mv文件夹,用来存放下载成功地资料
 58         NSString *folderPath = [cachePath stringByAppendingPathComponent:@"mv"];
 59         // 在缓存文件夹里创建mvTemp文件夹用来临时存放下载信息
 60         NSString *tempPath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"mvTemp"];
 61         // 判断缓存文件夹和视频存放文件夹是否存在,如果不存在,就创建一个文件夹
 62         if (![fileManager fileExistsAtPath:folderPath]) {// 如果不存在视频文件夹
 63             [fileManager createDirectoryAtPath:folderPath withIntermediateDirectories:YES attributes:nil error:nil];
 64         }
 65         if (![fileManager fileExistsAtPath:tempPath]) { // 如果不存在缓存文件夹
 66             [fileManager createDirectoryAtPath:tempPath withIntermediateDirectories:YES attributes:nil error:nil];
 67         }
 68         
 69         // 缓存路径(缓存当前下载的容量值)
 70         NSString *tempFilePath = [tempPath stringByAppendingPathComponent:@"mv.temp"];
 71         
 72         // 保存重启程序下载的进度(保存当前下载的进度值)
 73         NSString *txtFilePath = [tempPath stringByAppendingPathComponent:@"mv.txt"];
 74         
 75         // 文件保存路径
 76         NSString *mvFilePath = [folderPath stringByAppendingPathComponent:@"mv.mp4"];
 77         
 78         // 初始化下载字节数为0
 79         unsigned long long downloadedBytes = 0;
 80         // 创建请求
 81         NSURLRequest *request = [NSURLRequest requestWithURL:url];
 82         if ([fileManager fileExistsAtPath:tempFilePath]) {//如果存在,说明有缓存文件
 83             // 计算缓存文件的大小
 84             downloadedBytes = [self fileSizeAtPath:tempFilePath];
 85             NSLog(@"%llu",downloadedBytes);
 86             // 创建可变请求
 87             NSMutableURLRequest *mutableRequest = [request mutableCopy];
 88             NSString *requestRange = [NSString stringWithFormat:@"bytes=%llu-",downloadedBytes];
 89             
 90             [mutableRequest setValue:requestRange forHTTPHeaderField:@"Range"];
 91             request = mutableRequest;
 92             NSLog(@"==============断点下载");
 93         }
 94         
 95         if (![fileManager fileExistsAtPath:mvFilePath]) {
 96             [[NSURLCache sharedURLCache] removeCachedResponseForRequest:request];
 97             self.operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
 98             [self.operation setOutputStream:[NSOutputStream outputStreamToFileAtPath:tempFilePath append:YES]];
 99             
100             // 设置下载进度的block
101             __block ViewController *vc = self;
102             [self.operation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {
103                 // 更新进度
104                 vc.progressView.progress = ((float)totalBytesRead + downloadedBytes)/ (totalBytesExpectedToRead + downloadedBytes);
105                 vc.progressLabel.text = [NSString stringWithFormat:@"%.2f%%",self.progressView.progress * 100];
106                 // 将进度写入缓存文件
107                 NSString *progress = [NSString stringWithFormat:@"%.3f",((float)totalBytesRead + downloadedBytes) / ( totalBytesExpectedToRead + downloadedBytes)];
108                 [progress writeToFile:txtFilePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
109             }];
110             
111             // 下载完成时调用
112             [self.operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation * _Nonnull operation, id  _Nonnull responseObject) {
113                 //把下载完成的文件转移到保存的路径
114                 [fileManager moveItemAtPath:tempFilePath toPath:mvFilePath error:nil];
115                 //删除保存进度的txt文档
116                 [fileManager removeItemAtPath:txtFilePath error:nil];
117             } failure:^(AFHTTPRequestOperation * _Nonnull operation, NSError * _Nonnull error) {
118                 
119             }];
120             
121             // 开始操作
122             [self.operation start];
123         }
124     } else {
125         [sender setTitle:@"开始下载" forState:UIControlStateNormal];
126         [self.operation cancel];
127         self.operation = nil;
128     }
129 }
130 
131 /**
132  *  计算缓存文件的大小
133  *
134  *  @param fileAbsolutePath 文件的绝对路径
135  *
136  *  @return 文件的大小
137  */
138 - (unsigned long long)fileSizeAtPath:(NSString *)fileAbsolutePath {
139     signed long long fileSize = 0;
140     NSFileManager *fileManager = [NSFileManager new];
141     if ([fileManager fileExistsAtPath:fileAbsolutePath]) {
142         NSError *error = nil;
143         NSDictionary *fileDict = [fileManager attributesOfItemAtPath:fileAbsolutePath error:&error];
144         if (!error && fileDict) {
145             fileSize = [fileDict fileSize];
146         }
147     }
148     return fileSize;
149 }
150 
151 @end