ios开发网络学习四：NSURLConnection大文件断点下载

#import "ViewController.h"@interface ViewController ()<NSURLConnectionDataDelegate>
@property (weak, nonatomic) IBOutlet UIProgressView *progressView;@property (nonatomic, assign) NSInteger totalSize;
@property (nonatomic, assign) NSInteger currentSize;
/** 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@implementation ViewController- (IBAction)startBtnClick:(id)sender {
[self download];
}
- (IBAction)cancelBtnClick:(id)sender {
[self.connect cancel];
}
- (IBAction)goOnBtnClick:(id)sender {
[self download];
}//内存飙升
-(void)download
{
//1.url
// NSURL *url = [NSURL URLWithString:@"http://imgsrc.baidu.com/forum/w%3D580/sign=54a8cc6f728b4710ce2ffdc4f3cec3b2/d143ad4bd11373f06c0b5bd1a40f4bfbfbed0443.jpg"]; NSURL *url = [NSURL URLWithString:@"http://www.33lc.com/article/UploadPic/2012-10/2012102514201759594.jpg"]; //2.创建请求对象
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL: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
bytes=0- 请求100之后的所有数据
*/
NSString *range = [NSString stringWithFormat:@"bytes=%zd-",self.currentSize];
[request setValue:range forHTTPHeaderField:@"Range"];
NSLog(@"+++++++%@",range); //3.发送请求
NSURLConnection *connect = [[NSURLConnection alloc]initWithRequest:request delegate: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 >) {
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
[[NSFileManager defaultManager] createFileAtPath:self.fullPath contents:nil attributes:nil]; //NSDictionary *dict = [[NSFileManager defaultManager]attributesOfItemAtPath:self.fullPath error:nil]; //4.创建文件句柄(指针)
self.handle = [NSFileHandle fileHandleForWritingAtPath:self.fullPath];
}-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
//1.移动文件句柄到数据的末尾
[self.handle seekToEndOfFile]; //2.写数据
[self.handle writeData: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.handle closeFile];
self.handle = nil; NSLog(@"connectionDidFinishLoading");
NSLog(@"%@",self.fullPath);
}
@end