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#import "ViewController.h"
#define FileName @"121212.mp4"
@interface ViewController ()<NSURLSessionDataDelegate>
@property (weak, nonatomic) IBOutlet UIProgressView *proessView;
/** 接受响应体信息 */
@property (nonatomic, strong) NSFileHandle *handle;
@property (nonatomic, assign) NSInteger totalSize;
@property (nonatomic, assign) NSInteger currentSize;
@property (nonatomic, strong) NSString *fullPath;
@property (nonatomic, strong) NSURLSessionDataTask *dataTask;
@property (nonatomic, strong) NSURLSession *session;
@end
@implementation ViewController
-(void)viewDidLoad
{
[super viewDidLoad];
//1.读取保存的文件总大小的数据,0
//2.获得当前已经下载的数据的大小
//3.计算得到进度信息
}
-(NSString *)fullPath
{
if (_fullPath == nil) {
//获得文件全路径
_fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:FileName];
}
return _fullPath;
}
-(NSURLSession *)session
{
if (_session == nil) {
//3.创建会话对象,设置代理
/*
第一个参数:配置信息 [NSURLSessionConfiguration defaultSessionConfiguration]
第二个参数:代理
第三个参数:设置代理方法在哪个线程中调用
*/
_session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[NSOperationQueue mainQueue]];
}
return _session;
}
-(NSURLSessionDataTask *)dataTask
{
if (_dataTask == nil) {
//1.url
NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"];
//2.创建请求对象s
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
//3 设置请求头信息,告诉服务器请求那一部分数据
self.currentSize = [self getFileSize];
NSString *range = [NSString stringWithFormat:@"bytes=%zd-",self.currentSize];
[request setValue:range forHTTPHeaderField:@"Range"];
//4.创建Task
_dataTask = [self.session dataTaskWithRequest:request];
}
return _dataTask;
}
-(NSInteger)getFileSize
{
//获得指定文件路径对应文件的数据大小
NSDictionary *fileInfoDict = [[NSFileManager defaultManager]attributesOfItemAtPath:self.fullPath error:nil];
NSLog(@"%@",fileInfoDict);
NSInteger currentSize = [fileInfoDict[@"NSFileSize"] integerValue];
return currentSize;
}
- (IBAction)startBtnClick:(id)sender
{
[self.dataTask resume];
}
- (IBAction)suspendBtnClick:(id)sender
{
NSLog(@"_________________________suspend");
[self.dataTask suspend];
}
//注意:dataTask的取消是不可以恢复的
- (IBAction)cancelBtnClick:(id)sender
{
NSLog(@"_________________________cancel");
[self.dataTask cancel];
self.dataTask = nil;
}
- (IBAction)goOnBtnClick:(id)sender
{
NSLog(@"_________________________resume");
[self.dataTask resume];
}
#pragma mark ----------------------
#pragma mark NSURLSessionDataDelegate
/**
* 1.接收到服务器的响应 它默认会取消该请求
*
* @param session 会话对象
* @param dataTask 请求任务
* @param response 响应头信息
* @param completionHandler 回调 传给系统
*/
-(void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler
{
//获得文件的总大小
//expectedContentLength 本次请求的数据大小
self.totalSize = response.expectedContentLength + self.currentSize;
if (self.currentSize == 0) {
//创建空的文件
[[NSFileManager defaultManager]createFileAtPath:self.fullPath contents:nil attributes:nil];
}
//创建文件句柄
self.handle = [NSFileHandle fileHandleForWritingAtPath:self.fullPath];
//移动指针
[self.handle seekToEndOfFile];
/*
NSURLSessionResponseCancel = 0,取消 默认
NSURLSessionResponseAllow = 1, 接收
NSURLSessionResponseBecomeDownload = 2, 变成下载任务
NSURLSessionResponseBecomeStream 变成流
*/
completionHandler(NSURLSessionResponseAllow);
}
/**
* 接收到服务器返回的数据 调用多次
*
* @param session 会话对象
* @param dataTask 请求任务
* @param data 本次下载的数据
*/
-(void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data
{
//写入数据到文件
[self.handle writeData:data];
//计算文件的下载进度
self.currentSize += data.length;
NSLog(@"%f",1.0 * self.currentSize / self.totalSize);
self.proessView.progress = 1.0 * self.currentSize / self.totalSize;
}
/**
* 请求结束或者是失败的时候调用
*
* @param session 会话对象
* @param dataTask 请求任务
* @param error 错误信息
*/
-(void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
NSLog(@"%@",self.fullPath);
//关闭文件句柄
[self.handle closeFile];
self.handle = nil;
}
-(void)dealloc
{
//清理工作
//finishTasksAndInvalidate
[self.session invalidateAndCancel];
}
@end
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原文地址：http://www.cnblogs.com/liuzhenjie/p/5480169.html
