iOS開發中利用AFNetworking進行斷點下載
在iOS開發中我們如果要下載一個大的檔案可能會有斷點下載的需求即能夠對下載任務進行暫停,之後再開始下載任務,下面即將給出利用AFNetworking進行斷點下載的程式碼。核心思想:將下載的檔案的長度記錄下載,然後再次下載的時候即傳送網路請求的時候在請求頭中設定下載資料的位置。關鍵程式碼:
// 設定HTTP請求頭中的Range
NSString *range = [NSStringstringWithFormat:@"bytes=%zd-", self.currentLength];
[request setValue:range forHTTPHeaderField:@"Range"
全部程式碼:
.m檔案中的程式碼:
#import "AFNetworkingOfflineResumeDownloadFileViewController.h"
#import <AFNetworking.h>
@interface AFNetworkingOfflineResumeDownloadFileViewController ()
/** 下載進度條 */
@property (weak, nonatomic) IBOutletUIProgressView *progressView;
/** 下載進度條Label */
@property (weak
/** AFNetworking斷點下載(支援離線)需用到的屬性 **********/
/** 檔案的總長度 */
@property (nonatomic, assign) NSInteger fileLength;
/** 當前下載長度 */
@property (nonatomic, assign) NSInteger currentLength;
/** 檔案控制代碼物件 */
@property (nonatomic, strong) NSFileHandle *fileHandle;
/**
@property (nonatomic, strong) NSURLSessionDataTask *downloadTask;
/* AFURLSessionManager */
@property (nonatomic, strong) AFURLSessionManager *manager;
@end
@implementation AFNetworkingOfflineResumeDownloadFileViewController
- (void)viewDidLoad {
[superviewDidLoad];
self.navigationItem.title = @"AFNetworking斷點下載(支援離線)";
}
/**
* manager的懶載入
*/
- (AFURLSessionManager *)manager {
if (!_manager) {
NSURLSessionConfiguration *configuration = [NSURLSessionConfigurationdefaultSessionConfiguration];
// 1. 建立會話管理者
_manager = [[AFURLSessionManageralloc] initWithSessionConfiguration:configuration];
}
return_manager;
}
/**
* downloadTask的懶載入
*/
- (NSURLSessionDataTask *)downloadTask {
if (!_downloadTask) {
// 建立下載URL
NSURL *url = [NSURLURLWithString:@"http://dldir1.qq.com/qqfile/QQforMac/QQ_V5.4.0.dmg"];
// 2.建立request請求
NSMutableURLRequest *request = [NSMutableURLRequestrequestWithURL:url];
// 設定HTTP請求頭中的Range
NSString *range = [NSStringstringWithFormat:@"bytes=%zd-", self.currentLength];
[request setValue:range forHTTPHeaderField:@"Range"];
__weaktypeof(self) weakSelf = self;
_downloadTask = [self.managerdataTaskWithRequest:request completionHandler:^(NSURLResponse * _Nonnull response, id_Nullable responseObject, NSError * _Nullable error) {
NSLog(@"dataTaskWithRequest");
// 清空長度
weakSelf.currentLength = 0;
weakSelf.fileLength = 0;
// 關閉fileHandle
[weakSelf.fileHandlecloseFile];
weakSelf.fileHandle = nil;
}];
// 第一次收到伺服器的響應的block
[self.managersetDataTaskDidReceiveResponseBlock:^NSURLSessionResponseDisposition(NSURLSession * _Nonnull session, NSURLSessionDataTask * _Nonnull dataTask, NSURLResponse * _Nonnull response) {
NSLog(@"NSURLSessionResponseDisposition");
if (weakSelf.currentLength){
returnNSURLSessionResponseAllow;
}else{
// 獲得下載檔案的總長度:請求下載的檔案長度 + 當前已經下載的檔案長度
// weakSelf.fileLength = response.expectedContentLength + self.currentLength;
weakSelf.fileLength = response.expectedContentLength;
// 沙盒檔案路徑
NSString *path = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"QQ_V5.4.0.dmg"];
NSLog(@"File downloaded to: %@",path);
// 建立一個空的檔案到沙盒中
NSFileManager *manager = [NSFileManagerdefaultManager];
if (![manager fileExistsAtPath:path]) {
// 如果沒有下載檔案的話,就建立一個檔案。如果有下載檔案的話,則不用重新建立(不然會覆蓋掉之前的檔案)
[manager createFileAtPath:path contents:nilattributes:nil];
}
// 建立檔案控制代碼
weakSelf.fileHandle = [NSFileHandlefileHandleForWritingAtPath:path];
// 允許處理伺服器的響應,才會繼續接收伺服器返回的資料
returnNSURLSessionResponseAllow;
}
}];
// 收到伺服器返回的資料的block
[self.managersetDataTaskDidReceiveDataBlock:^(NSURLSession * _Nonnull session, NSURLSessionDataTask * _Nonnull dataTask, NSData * _Nonnull data) {
NSLog(@"setDataTaskDidReceiveDataBlock");
// 指定資料的寫入位置 -- 檔案內容的最後面
[weakSelf.fileHandleseekToEndOfFile];
// 向沙盒寫入資料
[weakSelf.fileHandlewriteData:data];
// 拼接檔案總長度
weakSelf.currentLength += data.length;
// 獲取主執行緒,不然無法正確顯示進度。
NSOperationQueue* mainQueue = [NSOperationQueuemainQueue];
[mainQueue addOperationWithBlock:^{
// 下載進度
if (weakSelf.fileLength == 0) {
weakSelf.progressView.progress = 0.0;
weakSelf.progressLabel.text = [NSStringstringWithFormat:@"當前下載進度:00.00%%"];
} else {
weakSelf.progressView.progress = 1.0 * weakSelf.currentLength / weakSelf.fileLength;
weakSelf.progressLabel.text = [NSStringstringWithFormat:@"當前下載進度:%.2f%%",100.0 * weakSelf.currentLength / weakSelf.fileLength];
}
}];
}];
}
return_downloadTask;
}
/**
* 點選按鈕 -- 使用AFNetworking斷點下載(支援離線)
*/
- (IBAction)OfflinResumeDownloadBtnClicked:(UIButton *)sender {
// 按鈕狀態取反
sender.selected = !sender.isSelected;
if (sender.selected) { // [開始下載/繼續下載]
// 沙盒檔案路徑
NSString *path = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"QQ_V5.4.0.dmg"];
NSInteger currentLength = [selffileLengthForPath:path];
if (currentLength > 0) { // [繼續下載]
self.currentLength = currentLength;
}
[self.downloadTaskresume];
} else {
// 暫停下載
[self.downloadTasksuspend];
self.downloadTask = nil;
}
}
/**
* 獲取已下載的檔案大小
*/
- (NSInteger)fileLengthForPath:(NSString *)path {
NSInteger fileLength = 0;
NSFileManager *fileManager = [[NSFileManageralloc] init]; // default is not thread safe
if ([fileManager fileExistsAtPath:path]) {
NSError *error = nil;
NSDictionary *fileDict = [fileManager attributesOfItemAtPath:path error:&error];
if (!error && fileDict) {
fileLength = [fileDict fileSize];
}
}
return fileLength;
}
@end