iOS断点续传:NSURLSession和NSURLSessionDataTask实现

小鱼儿 2022-07-30 15:24 213阅读 0赞

苹果提供的NSURLSessionDownloadTask虽然能实现断点续传，但是有些情况是无法处理的，比如程序强制退出或没有调用

cancelByProducingResumeData取消方法，这时就无法断点续传了。

使用NSURLSession和NSURLSessionDataTask实现断点续传的过程是：

1、配置NSMutableURLRequest对象的Range请求头字段信息

2、创建使用代理的NSURLSession对象

3、使用NSURLSession对象和NSMutableURLRequest对象创建NSURLSessionDataTask对象，启动任务。

4、在NSURLSessionDataDelegate的didReceiveData方法中追加获取下载数据到目标文件。

下面是具体实现，封装了一个续传管理器。可以直接拷贝到你的工程里，也可以参考我提供的DEMO：http://pan.baidu.com/s/1c0BHToW

//  MQLResumeManager.h

//  Created by MQL on 15/10/21.

\#import <Foundation/Foundation.h>

@interface MQLResumeManager : NSObject

/\*\*

\*  创建断点续传管理对象，启动下载请求

\*  @param url          文件资源地址

\*  @param targetPath   文件存放路径

\*  @param success      文件下载成功的回调块

\*  @param failure      文件下载失败的回调块

\*  @param progress     文件下载进度的回调块

\*  @return 断点续传管理对象

\*/

\+(MQLResumeManager\*)resumeManagerWithURL:(NSURL\*)url

targetPath:(NSString\*)targetPath

success:(void (^)())success

failure:(void (^)(NSError\*error))failure

progress:(void (^)(longlongtotalReceivedContentLength,long longtotalContentLength))progress;

/\*\*

\*  启动断点续传下载请求

\*/

\-(void)start;

/\*\*

\*  取消断点续传下载请求

\*/

\-(void)cancel;

@end

//  MQLResumeManager.m

//  Created by MQL on 15/10/21.

\#import "MQLResumeManager.h"

typedef void (^completionBlock)();

typedef void (^progressBlock)();

@interface MQLResumeManager ()<NSURLSessionDelegate,NSURLSessionTaskDelegate>

@property (nonatomic,strong)NSURLSession \*session;   //注意一个session只能有一个请求任务

@property(nonatomic,readwrite,retain)NSError \*error;//请求出错

@property(nonatomic,readwrite,copy)completionBlockcompletionBlock;

@property(nonatomic,readwrite,copy)progressBlock progressBlock;

@property (nonatomic,strong)NSURL \*url;          //文件资源地址

@property (nonatomic,strong)NSString \*targetPath;//文件存放路径

@property longlong totalContentLength;            //文件总大小

@property longlong totalReceivedContentLength;    //已下载大小

/\*\*

\*  设置成功、失败回调block

\*  @param success 成功回调block

\*  @param failure 失败回调block

\*/

\- (void)setCompletionBlockWithSuccess:(void (^)())success

failure:(void (^)(NSError\*error))failure;

/\*\*

\*  设置进度回调block

\*  @param progress

\*/

\-(void)setProgressBlockWithProgress:(void (^)(longlongtotalReceivedContentLength,long longtotalContentLength))progress;

/\*\*

\*  获取文件大小

\*  @param path 文件路径

\*  @return 文件大小

\*/

\- (long long)fileSizeForPath:(NSString \*)path;

@end

@implementation MQLResumeManager

/\*\*

\*  设置成功、失败回调block

\*  @param success 成功回调block

\*  @param failure 失败回调block

\*/

\- (void)setCompletionBlockWithSuccess:(void (^)())success

failure:(void (^)(NSError\*error))failure\{

\_\_weak typeof(self) weakSelf =self;

self.completionBlock = ^ \{

dispatch\_async(dispatch\_get\_main\_queue(), ^\{

if (weakSelf.error) \{

if (failure) \{

failure(weakSelf.error);

\} else \{

if (success) \{

success();

\});

\};

/\*\*

\*  设置进度回调block

\*  @param progress

\*/

\-(void)setProgressBlockWithProgress:(void (^)(longlongtotalReceivedContentLength,long longtotalContentLength))progress\{

\_\_weak typeof(self) weakSelf =self;

self.progressBlock = ^\{

dispatch\_async(dispatch\_get\_main\_queue(), ^\{

progress(weakSelf.totalReceivedContentLength, weakSelf.totalContentLength);

\});

\};

/\*\*

\*  获取文件大小

\*  @param path 文件路径

\*  @return 文件大小

\*/

\- (long long)fileSizeForPath:(NSString \*)path \{

long long fileSize =0;

NSFileManager \*fileManager = \[NSFileManagernew\];// not thread safe

if (\[fileManager fileExistsAtPath:path\]) \{

NSError \*error = nil;

NSDictionary \*fileDict = \[fileManager attributesOfItemAtPath:path error:&error\];

if (!error && fileDict) \{

fileSize = \[fileDict fileSize\];

return fileSize;

/\*\*

\*  创建断点续传管理对象，启动下载请求

\*  @param url          文件资源地址

\*  @param targetPath   文件存放路径

\*  @param success      文件下载成功的回调块

\*  @param failure      文件下载失败的回调块

\*  @param progress     文件下载进度的回调块

\*  @return 断点续传管理对象

\*/

\+(MQLResumeManager\*)resumeManagerWithURL:(NSURL\*)url

targetPath:(NSString\*)targetPath

success:(void (^)())success

failure:(void (^)(NSError\*error))failure

progress:(void (^)(longlongtotalReceivedContentLength,long longtotalContentLength))progress\{

MQLResumeManager \*manager = \[\[MQLResumeManageralloc\]init\];

manager.url = url;

manager.targetPath = targetPath;

\[manager setCompletionBlockWithSuccess:successfailure:failure\];

\[manager setProgressBlockWithProgress:progress\];

manager.totalContentLength =0;

manager.totalReceivedContentLength =0;

return manager;

/\*\*

\*  启动断点续传下载请求

\*/

\-(void)start\{

NSMutableURLRequest \*request = \[\[NSMutableURLRequestalloc\]initWithURL:self.url\];

longlong downloadedBytes =self.totalReceivedContentLength = \[selffileSizeForPath:self.targetPath\];

if (downloadedBytes > 0) \{

NSString \*requestRange = \[NSStringstringWithFormat:@"bytes=%llu-", downloadedBytes\];

\[request setValue:requestRange forHTTPHeaderField:@"Range"\];

\}else\{

int fileDescriptor = open(\[self.targetPathUTF8String\],O\_CREAT |O\_EXCL |O\_RDWR,0666);

if (fileDescriptor > 0) \{

close(fileDescriptor);

NSURLSessionConfiguration \*sessionConfiguration = \[NSURLSessionConfigurationdefaultSessionConfiguration\];

NSOperationQueue \*queue = \[\[NSOperationQueuealloc\]init\];

self.session = \[NSURLSessionsessionWithConfiguration:sessionConfigurationdelegate:selfdelegateQueue:queue\];

NSURLSessionDataTask \*dataTask = \[self.sessiondataTaskWithRequest:request\];

\[dataTask resume\];

/\*\*

\*  取消断点续传下载请求

\*/

\-(void)cancel\{

if (self.session) \{

\[self.sessioninvalidateAndCancel\];

self.session =nil;

\#pragma mark -- NSURLSessionDelegate

/\* The last message a session delegate receives.  A session will only become

\* invalid because of a systemic error or when it has been

\* explicitly invalidated, in which case the error parameter will be nil.

\*/

\- (void)URLSession:(NSURLSession \*)session didBecomeInvalidWithError:(nullableNSError \*)error\{

NSLog(@"didBecomeInvalidWithError");

\#pragma mark -- NSURLSessionTaskDelegate

/\* Sent as the last message related to a specific task.  Error may be

\* nil, which implies that no error occurred and this task is complete.

\*/

\- (void)URLSession:(NSURLSession \*)session task:(NSURLSessionTask\*)task

didCompleteWithError:(nullable NSError \*)error\{

NSLog(@"didCompleteWithError");

if (error == nil &&self.error ==nil) \{

self.completionBlock();

\}else if (error !=nil)\{

if (error.code != -999) \{

self.error = error;

self.completionBlock();

\}else if (self.error !=nil)\{

self.completionBlock();

\#pragma mark -- NSURLSessionDataDelegate

/\* Sent when data is available for the delegate to consume.  It is

\* assumed that the delegate will retain and not copy the data.  As

\* the data may be discontiguous, you should use

\* \[NSData enumerateByteRangesUsingBlock:\] to access it.

\*/

\- (void)URLSession:(NSURLSession \*)session dataTask:(NSURLSessionDataTask \*)dataTask

didReceiveData:(NSData \*)data\{

//根据status code的不同，做相应的处理

NSHTTPURLResponse \*response = (NSHTTPURLResponse\*)dataTask.response;

if (response.statusCode ==200) \{

self.totalContentLength = dataTask.countOfBytesExpectedToReceive;

\}else if (response.statusCode ==206)\{

NSString \*contentRange = \[response.allHeaderFieldsvalueForKey:@"Content-Range"\];

if (\[contentRange hasPrefix:@"bytes"\]) \{

NSArray \*bytes = \[contentRangecomponentsSeparatedByCharactersInSet:\[NSCharacterSetcharacterSetWithCharactersInString:@" -/"\]\];

if (\[bytes count\] == 4) \{

self.totalContentLength = \[\[bytesobjectAtIndex:3\]longLongValue\];

\}else if (response.statusCode ==416)\{

NSString \*contentRange = \[response.allHeaderFieldsvalueForKey:@"Content-Range"\];

if (\[contentRange hasPrefix:@"bytes"\]) \{

NSArray \*bytes = \[contentRangecomponentsSeparatedByCharactersInSet:\[NSCharacterSetcharacterSetWithCharactersInString:@" -/"\]\];

if (\[bytes count\] == 3) \{

self.totalContentLength = \[\[bytesobjectAtIndex:2\]longLongValue\];

if (self.totalReceivedContentLength==self.totalContentLength) \{

//说明已下完

//更新进度

self.progressBlock();

\}else\{

//416 Requested Range Not Satisfiable

self.error = \[\[NSErroralloc\]initWithDomain:\[self.urlabsoluteString\]code:416userInfo:response.allHeaderFields\];

return;

\}else\{

//其他情况还没发现

return;

//向文件追加数据

NSFileHandle \*fileHandle = \[NSFileHandlefileHandleForUpdatingAtPath:self.targetPath\];

\[fileHandle seekToEndOfFile\]; //将节点跳到文件的末尾

\[fileHandle writeData:data\];//追加写入数据

\[fileHandle closeFile\];

//更新进度

self.totalReceivedContentLength += data.length;

self.progressBlock();

@end

iOS断点续传:NSURLSession和NSURLSessionDataTask实现

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