iOS开发网络篇—多线程断点下载

 1 #import "YYViewController.h"
 2 #import "YYFileMultiDownloader.h"
 3 
 4 @interface YYViewController ()
 5 @property (nonatomic, strong) YYFileMultiDownloader *fileMultiDownloader;
 6 @end
 7 
 8 @implementation YYViewController
 9 -  (YYFileMultiDownloader *)fileMultiDownloader
10 {
11     if (!_fileMultiDownloader) {
12         _fileMultiDownloader = [[YYFileMultiDownloader alloc] init];
13         // 需要下载的文件远程URL
14         _fileMultiDownloader.url = @"http://192.168.1.200:8080/MJServer/resources/jre.zip";
15         // 文件保存到什么地方
16         NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
17         NSString *filepath = [caches stringByAppendingPathComponent:@"jre.zip"];
18         _fileMultiDownloader.destPath = filepath;
19     }
20     return _fileMultiDownloader;
21 }
22 
23 - (void)viewDidLoad
24 {
25     [super viewDidLoad];
26     
27 }
28 
29 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
30 {
31     [self.fileMultiDownloader start];
32 }
33 
34 @end

 1 #import <Foundation/Foundation.h>
 2 
 3 @interface YYFileDownloader : NSObject
 4 {
 5     BOOL _downloading;
 6 }
 7 /**
 8  * 所需要下载文件的远程URL(连接服务器的路径)
 9  */
10 @property (nonatomic, copy) NSString *url;
11 /**
12  * 文件的存储路径(文件下载到什么地方)
13  */
14 @property (nonatomic, copy) NSString *destPath;
15 
16 /**
17  * 是否正在下载(有没有在下载, 只有下载器内部才知道)
18  */
19 @property (nonatomic, readonly, getter = isDownloading) BOOL downloading;
20 
21 /**
22  * 用来监听下载进度
23  */
24 @property (nonatomic, copy) void (^progressHandler)(double progress);
25 
26 /**
27  * 开始(恢复)下载
28  */
29 - (void)start;
30 
31 /**
32  * 暂停下载
33  */
34 - (void)pause;
35 @end

1 #import "YYFileDownloader.h"
2 
3 @implementation YYFileDownloader
4 @end

 1 #import "YYFileDownloader.h"
 2 
 3 @interface YYFileSingleDownloader : YYFileDownloader
 4 /**
 5  *  开始的位置
 6  */
 7 @property (nonatomic, assign) long long begin;
 8 /**
 9  *  结束的位置
10  */
11 @property (nonatomic, assign) long long end; 
12 @end

  1 #import "YYFileSingleDownloader.h"
  2 @interface YYFileSingleDownloader() <NSURLConnectionDataDelegate>
  3 /**
  4  * 连接对象
  5  */
  6 @property (nonatomic, strong) NSURLConnection *conn;
  7 
  8 /**
  9  *  写数据的文件句柄
 10  */
 11 @property (nonatomic, strong) NSFileHandle *writeHandle;
 12 /**
 13  *  当前已下载数据的长度
 14  */
 15 @property (nonatomic, assign) long long currentLength;
 16 @end
 17 
 18 @implementation YYFileSingleDownloader
 19 
 20 - (NSFileHandle *)writeHandle
 21 {
 22     if (!_writeHandle) {
 23         _writeHandle = [NSFileHandle fileHandleForWritingAtPath:self.destPath];
 24     }
 25     return _writeHandle;
 26 }
 27 
 28 /**
 29  * 开始(恢复)下载
 30  */
 31 - (void)start
 32 {
 33     NSURL *url = [NSURL URLWithString:self.url];
 34     // 默认就是GET请求
 35     NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
 36     // 设置请求头信息
 37     NSString *value = [NSString stringWithFormat:@"bytes=%lld-%lld", self.begin + self.currentLength, self.end];
 38     [request setValue:value forHTTPHeaderField:@"Range"];
 39     self.conn = [NSURLConnection connectionWithRequest:request delegate:self];
 40     
 41     _downloading = YES;
 42 }
 43 
 44 /**
 45  * 暂停下载
 46  */
 47 - (void)pause
 48 {
 49     [self.conn cancel];
 50     self.conn = nil;
 51     
 52     _downloading = NO;
 53 }
 54 
 55 
 56 #pragma mark - NSURLConnectionDataDelegate 代理方法
 57 /**
 58  *  1. 当接受到服务器的响应(连通了服务器)就会调用
 59  */
 60 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
 61 {
 62     
 63 }
 64 
 65 /**
 66  *  2. 当接受到服务器的数据就会调用(可能会被调用多次, 每次调用只会传递部分数据)
 67  */
 68 - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
 69 {
 70     // 移动到文件的尾部
 71     [self.writeHandle seekToFileOffset:self.begin + self.currentLength];
 72     // 从当前移动的位置(文件尾部)开始写入数据
 73     [self.writeHandle writeData:data];
 74     
 75     // 累加长度
 76     self.currentLength += data.length;
 77     
 78     // 打印下载进度
 79     double progress = (double)self.currentLength / (self.end - self.begin);
 80     if (self.progressHandler) {
 81         self.progressHandler(progress);
 82     }
 83 }
 84 
 85 /**
 86  *  3. 当服务器的数据接受完毕后就会调用
 87  */
 88 - (void)connectionDidFinishLoading:(NSURLConnection *)connection
 89 {
 90     // 清空属性值
 91     self.currentLength = 0;
 92     
 93     // 关闭连接(不再输入数据到文件中)
 94     [self.writeHandle closeFile];
 95     self.writeHandle = nil;
 96 }
 97 
 98 /**
 99  *  请求错误(失败)的时候调用(请求超时\断网\没有网, 一般指客户端错误)
100  */
101 - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
102 {
103     
104 }
105 
106 @end

1 #import "YYFileDownloader.h"
2  
3 @interface YYFileMultiDownloader : YYFileDownloader
4  
5 @end