ios-断点续传

//断点续传

#import "ViewController.h"

#import "ResumeDowdload.h"

@interface ViewController ()
{
ResumeDowdload *_resume;
float _pv;
}

@property(nonatomic,weak)IBOutlet UIButton *cancelbutton;

@property(nonatomic,weak)IBOutlet UIButton *continuebutton;

@property(nonatomic,weak)IBOutlet UIImageView *imageView;

@property(nonatomic,weak)IBOutlet UIProgressView *progressView;

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];

self.imageView.backgroundColor = [UIColor grayColor];
_pv = 0.0;
self.progressView.hidden = YES;
// Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.
}

-(IBAction)downloadStart:(id)sender
{
//NSString *urlStr = @"http://farm3.staticflickr.com/2846/9823925914_78cd653ac9_b_d.jpg";
NSString *urlStr = @"http://10.0.166.136/6ca014e5jw1etbxl.png";
_resume = [[ResumeDowdload alloc]init];
_resume.fileUrl = urlStr;

_resume.delegate = self;

_resume.updataingMethod =@selector(updataing:);
_resume.updataingFinishMethod = @selector(updataFinish:);
_resume.updataingFailMethod = @selector(updataFail:);

//开始下载
[_resume requestFromUrl];
self.progressView.hidden = NO;
self.progressView.progress = _pv;

}
/**
*  下载失败
*
*  @param rd <#rd description#>
*/
-(void)updataFail:(ResumeDowdload *)rd{
NSLog(@"文件下载失败：%@",[rd localPath]);
}

/**
*  下载完成
*
*  @param rd <#rd description#>
*/
-(void)updataFinish:(ResumeDowdload *)rd{
self.progressView.hidden = YES;
if ([rd localPath]) {
self.imageView.image = [UIImage imageWithContentsOfFile:rd.localPath];
}
NSLog(@"文件下载完成");
}

-(void)updataing:(ResumeDowdload *)rd{
_pv = [rd.downloadSize longLongValue]/[rd.fileSize longLongValue];
self.progressView.progress = _pv;
NSLog(@"进度条：%f",_pv);
}

-(IBAction)downloadStop:(id)sender
{
if (_resume) {
[_resume stopDownload];
}
}

@end

#import <Foundation/Foundation.h>

@interface ResumeDowdload : NSObject<NSURLConnectionDataDelegate>
{
//网络连接
NSURLConnection *_httpConnection;
//文件句柄
NSFileHandle *_fileHandle;
}

//要下载文件的地址
@property(nonatomic,retain)NSString *fileUrl;

//要下载文件的大小
@property(nonatomic,retain)NSNumber *fileSize;

//已经下载了的大小
@property(nonatomic,retain)NSNumber *downloadSize;

//从指定的网址获取数据
-(void)requestFromUrl;

//代理对象
@property(nonatomic,assign)id delegate;

//更新下载进度的回调方法
@property(nonatomic,assign)SEL updataingMethod;

//更新下载完成的回调方法
@property(nonatomic,assign)SEL updataingFinishMethod;

//更新下载失败的回调方法
@property(nonatomic,assign)SEL updataingFailMethod;

@property(nonatomic,assign)SEL method;

//停止下载
-(void)stopDownload;

//获取当前文件的路径
-(NSString *)localPath;

@end

#import "ResumeDowdload.h"
#import "NSString+MD5Addition.h"

@implementation ResumeDowdload

-(id)init
{
if (self = [super init]) {

}
return self;
}

//从指定的网址获取数据
-(void)requestFromUrl
{
//断点续传请求部分

NSURL *url = [NSURL URLWithString:self.fileUrl];
//用可变的
//将网址转换成可变请求对象
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

//获取当前下载的大小
NSString *rangeStr = [NSString stringWithFormat:@"bytes=%lld-",[self.downloadSize longLongValue]];
//根据当前下载的大小设置请求数据范围
[request setValue:rangeStr forHTTPHeaderField:@"Range"];

//创建连接
_httpConnection = [[NSURLConnection alloc]initWithRequest:request delegate:self];

NSLog(@"downloadSize:%@",self.downloadSize);

}

//停止下载
-(void)stopDownload
{
//如果句柄存在 则关闭文件，自行释放
if(_fileHandle){
[_fileHandle closeFile];
_fileHandle = nil;
}
//停止下载
[_httpConnection cancel];
//释放对象
_httpConnection = nil;
}

//获取当前文件的路径
-(NSString *)localPath
{
//返回当前沙盒的路径
NSString *path = NSHomeDirectory();

//根据文件的url加密后命名文件名，保证
NSString *fileName = [self.fileUrl stringFromMD5];

path = [path stringByAppendingPathComponent:[NSString stringWithFormat:@"Documents/%@",fileName]];

return path;

}

#pragma mark -用代理形式异步请求-
//调用它就证明，连接有响应，已经下载完响应头，开始下载
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{

NSLog(@"%@",NSStringFromSelector(_cmd));

//文件为什么要关闭
if(_fileHandle){
[_fileHandle closeFile];
}
//获取总文件大小
self.fileSize = [NSNumber numberWithLongLong :response.expectedContentLength];
//如果当前不存在文件，则创建一个
NSFileManager *mg = [NSFileManager defaultManager];
if (![mg fileExistsAtPath:[self localPath]]) {
//创建 判断 查找 contents 是指数据 当前没有
[mg createFileAtPath:[self localPath] contents:nil attributes:nil];
}
//获取文件句柄 是更新用的（更具文件路径获取文件句柄，用来操作文件），更新类型的句柄
_fileHandle = [NSFileHandle fileHandleForUpdatingAtPath:[self localPath]];

//将文件指针移动到文件结尾
[_fileHandle seekToEndOfFile];

//设置已经下载文件的大小
self.downloadSize = [NSNumber numberWithLongLong:[_fileHandle offsetInFile]];

NSLog(@"downloadSize:%@",self.downloadSize);
/**
*  要下载之前，先要取到文件的句柄，将文件的句柄移动到末尾，给我们返回当前文件的大小
*/
}
//调用它证明正在接受数据,响应体，根据数据大小,反复不间断的接收
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
//不间断的接受数据

//将接受到的数据写入文件
[_fileHandle writeData:data];

//计算已经下载的大小   先写入再计算
unsigned long long newDownloadSize = [self.downloadSize longLongValue] + [data length];

//重新设置已经下载的大小

self.downloadSize = [NSNumber numberWithLongLong:newDownloadSize];
/**
*  PS：此时句柄在末尾，写入即追加数据，重新设置已经下载的大小
*/
NSLog(@"downloadSize:%@",self.downloadSize);
//需要通知代理进行更新
//检查代理是否实现了这个方法
if([self.delegate respondsToSelector:self.updataingMethod])
{

[self.delegate performSelector:self.updataingMethod withObject:self];
}

NSLog(@"%s",__func__);
}
//调用它就证明已经下载完毕 下载成功
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{

//文件下载完成 关闭文件，让Handle 释放(释放对象)
if(_fileHandle)
{
[_fileHandle closeFile];
_fileHandle = nil;
}

if ([self.delegate respondsToSelector:self.updataingFinishMethod]) {
[self.delegate performSelector:self.updataingMethod withObject:self];
}

NSLog(@"%s",__func__);
}

//连接发生错误下载失败
//1.断网了
//2.
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
NSLog(@"下载失败");
if ([self.delegate respondsToSelector:self.updataingFailMethod]) {
[self.delegate performSelector:self.updataingMethod withObject:self];
}

NSLog(@"%s",__func__);
}

@end