ios大檔案下載之開始和暫停

標籤：

  1 #import "HMViewController.h"  2   3 @interface HMViewController ()  4 @property (weak, nonatomic) IBOutlet UIProgressView *progressView;  5 /**  6  *  寫資料的檔案控制代碼  7  */  8 @property (nonatomic, strong) NSFileHandle *writeHandle;  9 /** 10  *  當前已下載資料的長度 11  */ 12 @property (nonatomic, assign) long long currentLength; 13 /** 14  *  完整檔案的總長度 15  */ 16 @property (nonatomic, assign) long long totalLength; 17  18 /** 19  * 連線物件 20  */ 21 @property (nonatomic, strong) NSURLConnection *conn; 22  23 /** 24  * 是否在下載 25  */ 26 @property (nonatomic, assign, getter = isDownloading) BOOL downloading; 27  28 - (IBAction)start:(UIButton *)button; 29 @end 30  31 @implementation HMViewController 32  33 - (void)viewDidLoad 34 { 35     [super viewDidLoad]; 36      37 } 38  39 // 按鈕文字: "開始", "暫停" 40 - (IBAction)start:(UIButton *)button { // self.currentLength == 200 41     if (self.isDownloading) { // 暫停下載 42         self.downloading = NO; 43          44         [button setTitle:@"開始" forState:UIControlStateNormal]; 45          46         // 取消當前的請求 47         [self.conn cancel]; 48         self.conn = nil; 49     } else { // 開始下載 50         self.downloading = YES; 51          52         [button setTitle:@"暫停" forState:UIControlStateNormal]; 53          54         NSURL *url = [NSURL URLWithString:@"http://192.168.1.200:8080/MJServer/resources/jre.zip"]; 55         // 預設就是GET請求 56         NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; 57         // 佈建要求頭資訊 58         NSString *value = [NSString stringWithFormat:@"bytes=%lld-", self.currentLength]; 59         [request setValue:value forHTTPHeaderField:@"Range"]; 60         self.conn = [NSURLConnection connectionWithRequest:request delegate:self]; 61     } 62 } 63  64 #pragma mark - NSURLConnectionDataDelegate 代理方法 65 /** 66  *  1. 當接受到伺服器的響應(連通了伺服器)就會調用 67  */ 68 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response 69 { 70 #warning 一定要判斷 71     if (self.totalLength) return; 72      73     // 0.檔案的儲存路徑 74     NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject]; 75     NSString *filepath = [caches stringByAppendingPathComponent:@"jre.zip"]; 76      77     // 1.建立一個空的檔案到沙箱中 78     NSFileManager *mgr = [NSFileManager defaultManager]; 79     // 剛建立完畢的大小是0位元組 80     [mgr createFileAtPath:filepath contents:nil attributes:nil]; 81      82     // 2.建立寫資料的檔案控制代碼 83     self.writeHandle = [NSFileHandle fileHandleForWritingAtPath:filepath]; 84      85     // 3.獲得完整檔案的長度 86     self.totalLength = response.expectedContentLength; 87 } 88  89 /** 90  *  2. 當接受到伺服器的資料就會調用(可能會被調用多次, 每次調用只會傳遞部分資料) 91  */ 92 - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 93 { 94     // 累加長度 95     self.currentLength += data.length; 96      97     // 顯示進度 98     double progress = (double)self.currentLength / self.totalLength; 99     self.progressView.progress = progress;100     101     // 移動到檔案的尾部102     [self.writeHandle seekToEndOfFile];103     // 從當前移動的位置(檔案尾部)開始寫入資料104     [self.writeHandle writeData:data];105 }106 107 /**108  *  3. 當伺服器的資料接受完畢後就會調用109  */110 - (void)connectionDidFinishLoading:(NSURLConnection *)connection111 {112     NSLog(@"connectionDidFinishLoading----");113     114     // 清空屬性值115     self.currentLength = 0;116     self.totalLength = 0;117     118     // 關閉串連(不再輸入資料到檔案中)119     [self.writeHandle closeFile];120     self.writeHandle = nil;121 }122 123 /**124  *  請求錯誤(失敗)的時候調用(請求逾時\斷網\沒有網, 一般指用戶端錯誤)125  */126 - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error127 {128     129 }130 @end

 

ios大檔案下載之開始和暫停