NSURLConnection实现大文件断点下载：主要通过设置请求头告诉服务器要下载视频某一部分，以及句柄。
#import"ViewController.h"
@interfaceViewController()
@property(weak,nonatomic)IBOutletUIProgressView*progressView;
@property(nonatomic,assign)NSIntegertotalSize;
@property(nonatomic,assign)NSIntegercurrentSize;
/**文件句柄*/
@property(nonatomic,strong)NSFileHandle*handle;
/**沙盒路径*/
@property(nonatomic,strong)NSString*fullPath;
/**连接对象*/
@property(nonatomic,strong)NSURLConnection*connect;
@end
@implementationViewController
- (IBAction)startBtnClick:(id)sender {
[selfdownload];
}
- (IBAction)cancelBtnClick:(id)sender {
[self.connectcancel];
}
- (IBAction)goOnBtnClick:(id)sender {
[selfdownload];
}
//内存飙升
-(void)download
{
//1.url
NSURL*url = [NSURLURLWithString:@"http://www.33lc.com/article/UploadPic/2012-10/2012102514201759594.jpg"];
//2.创建请求对象
NSMutableURLRequest*request = [NSMutableURLRequestrequestWithURL:url];
//设置请求头信息,告诉服务器值请求一部分数据range
/*
bytes=0-100
bytes=-100 最后100个字节
bytes=100-请求100之后的所有数据
*/
NSString*range = [NSStringstringWithFormat:@"bytes=%zd-",self.currentSize];
[requestsetValue:rangeforHTTPHeaderField:@"Range"];
NSLog(@"+++++++%@",range);
//3.发送请求
NSURLConnection*connect = [[NSURLConnectionalloc]initWithRequest:requestdelegate:self];
self.connect= connect;
}
#pragma mark ----------------------
#pragma mark NSURLConnectionDataDelegate
-(void)connection:(NSURLConnection*)connection didReceiveResponse:(NSURLResponse*)response
{
NSLog(@"didReceiveResponse");
//1.得到文件的总大小(本次请求的文件数据的总大小!=文件的总大小)
// self.totalSize = response.expectedContentLength + self.currentSize;
if(self.currentSize>0) {
return;
}
self.totalSize= response.expectedContentLength;
//2.写数据到沙盒中
self.fullPath= [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory,NSUserDomainMask,YES)lastObject]stringByAppendingPathComponent:@"123.jpg"];
NSLog(@"%@",self.fullPath);
//3.创建一个空的文件
[[NSFileManagerdefaultManager]createFileAtPath:self.fullPathcontents:nilattributes:nil];
//NSDictionary *dict = [[NSFileManager defaultManager]attributesOfItemAtPath:self.fullPath error:nil];
//4.创建文件句柄(指针)
self.handle= [NSFileHandlefileHandleForWritingAtPath:self.fullPath];
}
-(void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
{
//1.移动文件句柄到数据的末尾
[self.handleseekToEndOfFile];
//2.写数据
[self.handlewriteData:data];
//3.获得进度
self.currentSize+= data.length;
//进度=已经下载/文件的总大小
NSLog(@"%f",1.0*self.currentSize/self.totalSize);
self.progressView.progress=1.0*self.currentSize/self.totalSize;
//NSLog(@"%@",self.fullPath);
}
-(void)connection:(NSURLConnection*)connection didFailWithError:(NSError*)error
{
}
-(void)connectionDidFinishLoading:(NSURLConnection*)connection
{
//1.关闭文件句柄
[self.handlecloseFile];
self.handle=nil;
NSLog(@"connectionDidFinishLoading");
NSLog(@"%@",self.fullPath);
}
@end