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ios开发网络学习三：NSURLConnection小文件大文件下载
一：小文件下载
#import "ViewController.h"@interface ViewController ()<NSURLConnectionDataDelegate>/** 注释 */@property (nonatomic, strong) NSMutableData *fileData;@property (nonatomic, assign) NSInteger totalSize;@property (weak, nonatomic) IBOutlet UIImageView *imageView;@end@implementation ViewController-(NSMutableData *)fileData{ if (_fileData =http://www.mamicode.com/= nil) { _fileData = [NSMutableData data]; } return _fileData;}-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{ [self download3];}//耗时操作[NSData dataWithContentsOfURL:url]-(void)download1{ //1.url NSURL *url = [NSURL URLWithString:@"http://img5.imgtn.bdimg.com/it/u=1915764121,2488815998&fm=21&gp=0.jpg"]; //2.下载二进制数据 NSData *data =http://www.mamicode.com/ [NSData dataWithContentsOfURL:url]; //3.转换 UIImage *image = [UIImage imageWithData:data];}//1.无法监听进度//2.内存飙升-(void)download2{ //1.url // NSURL *url = [NSURL URLWithString:@"http://imgsrc.baidu.com/forum/w%3D580/sign=54a8cc6f728b4710ce2ffdc4f3cec3b2/d143ad4bd11373f06c0b5bd1a40f4bfbfbed0443.jpg"]; NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"]; //2.创建请求对象 NSURLRequest *request = [NSURLRequest requestWithURL:url]; //3.发送请求 [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) { //4.转换// UIImage *image = [UIImage imageWithData:data];// // self.imageView.image = image; //NSLog(@"%@",connectionError); //4.写数据到沙盒中 NSString *fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject]stringByAppendingPathComponent:@"123.mp4"]; [data writeToFile:fullPath atomically:YES]; }];}//内存飙升-(void)download3{ //1.url // NSURL *url = [NSURL URLWithString:@"http://imgsrc.baidu.com/forum/w%3D580/sign=54a8cc6f728b4710ce2ffdc4f3cec3b2/d143ad4bd11373f06c0b5bd1a40f4bfbfbed0443.jpg"]; NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"]; //2.创建请求对象 NSURLRequest *request = [NSURLRequest requestWithURL:url]; //3.发送请求 [[NSURLConnection alloc]initWithRequest:request delegate:self];}#pragma mark ----------------------#pragma mark NSURLConnectionDataDelegate/** * 1:当接收到服务器响应的时候调用：只调用一次 * */-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{ NSLog(@"didReceiveResponse"); //得到文件的总大小(本次请求的文件数据的总大小) self.totalSize = response.expectedContentLength;}/** * 2:当下载数据的时候调用，可能被调用多次：在此方法内部有时需要拼接data，也可以在此方法中获得下载的进度 * */-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{ // NSLog(@"%zd",data.length); [self.fileData appendData:data]; //进度=已经下载/文件的总大小 NSLog(@"%f",1.0 * self.fileData.length /self.totalSize);}/** * 3:下载失败的时候的调用 * */-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{}/** * 4:下载成功的时候调用 * */-(void)connectionDidFinishLoading:(NSURLConnection *)connection{ NSLog(@"connectionDidFinishLoading"); //4.写数据到沙盒中 NSString *fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject]stringByAppendingPathComponent:@"123.mp4"]; [self.fileData writeToFile:fullPath atomically:YES]; NSLog(@"%@",fullPath);}/** * 三种方法的区别：1：耗时操作[NSData dataWithContentsOfURL:url] 2：sendAsynchronousRequest，无法监听进度 3：可以进行进度的监听，以及对下载完成后数据的处理 */@end
（1）第一种方式（NSData）
```objc
//使用NSDta直接加载网络上的url资源（不考虑线程）
-(void)dataDownload
{
//1.确定资源路径
NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/images/minion_01.png"];
//2.根据URL加载对应的资源
NSData *data = http://www.mamicode.com/[NSData dataWithContentsOfURL:url];
//3.转换并显示数据
UIImage *image = [UIImage imageWithData:data];
self.imageView.image = image;
}
```
（2）第二种方式（NSURLConnection-sendAsync）
```objc
//使用NSURLConnection发送异步请求下载文件资源
-(void)connectDownload
{
//1.确定请求路径
NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/images/minion_01.png"];
//2.创建请求对象
NSURLRequest *request = [NSURLRequest requestWithURL:url];
//3.使用NSURLConnection发送一个异步请求
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
//4.拿到并处理数据
UIImage *image = [UIImage imageWithData:data];
self.imageView.image = image;
}];
}
```
（3）第三种方式（NSURLConnection-delegate）
```objc
//使用NSURLConnection设置代理发送异步请求的方式下载文件
-(void)connectionDelegateDownload
{
//1.确定请求路径
NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"];
//2.创建请求对象
NSURLRequest *request = [NSURLRequest requestWithURL:url];
//3.使用NSURLConnection设置代理并发送异步请求
[NSURLConnection connectionWithRequest:request delegate:self];
}
#pragma mark--NSURLConnectionDataDelegate
//当接收到服务器响应的时候调用，该方法只会调用一次
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
//创建一个容器，用来接收服务器返回的数据
self.fileData = http://www.mamicode.com/[NSMutableData data];
//获得当前要下载文件的总大小（通过响应头得到）
NSHTTPURLResponse *res = (NSHTTPURLResponse *)response;
self.totalLength = res.expectedContentLength;
NSLog(@"%zd",self.totalLength);
//拿到服务器端推荐的文件名称
self.fileName = res.suggestedFilename;
}
//当接收到服务器返回的数据时会调用
//该方法可能会被调用多次
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// NSLog(@"%s",__func__);
//拼接每次下载的数据
[self.fileData appendData:data];
//计算当前下载进度并刷新UI显示
self.currentLength = self.fileData.length;
NSLog(@"%f",1.0* self.currentLength/self.totalLength);
self.progressView.progress = 1.0* self.currentLength/self.totalLength;
}
//当网络请求结束之后调用
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
//文件下载完毕把接受到的文件数据写入到沙盒中保存
//1.确定要保存文件的全路径
//caches文件夹路径
NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
NSString *fullPath = [caches stringByAppendingPathComponent:self.fileName];
//2.写数据到文件中
[self.fileData writeToFile:fullPath atomically:YES];
NSLog(@"%@",fullPath);
}
//当请求失败的时候调用该方法
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
NSLog(@"%s",__func__);
}
```
二：大文件下载
#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;@end@implementation ViewController/** * 1:大文件下载的时候，不断的拼接二进制数据，此时会导致内存的飙升，所以此时应该用文件句柄去写文件，创建一个空文件夹，创建文件句柄对象，将下载的文件一点一点拼接到空文件夹内。在文件下载完毕后，要关闭文件句柄，并设为nil空值 * */-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{ [self download3];}//内存飙升-(void)download3{ //1.url // NSURL *url = [NSURL URLWithString:@"http://imgsrc.baidu.com/forum/w%3D580/sign=54a8cc6f728b4710ce2ffdc4f3cec3b2/d143ad4bd11373f06c0b5bd1a40f4bfbfbed0443.jpg"]; NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"]; //2.创建请求对象 NSURLRequest *request = [NSURLRequest requestWithURL:url]; //3.发送请求 [[NSURLConnection alloc]initWithRequest:request delegate:self];}#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) self.totalSize = response.expectedContentLength; //2.写数据到沙盒中 self.fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject]stringByAppendingPathComponent:@"123.mp4"]; //3.创建一个空的文件 [[NSFileManager defaultManager] createFileAtPath:self.fullPath contents:nil attributes: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
（1）第一种方式（NSData）
```objc
//使用NSDta直接加载网络上的url资源（不考虑线程）
-(void)dataDownload
{
//1.确定资源路径
NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/images/minion_01.png"];
//2.根据URL加载对应的资源
NSData *data = http://www.mamicode.com/[NSData dataWithContentsOfURL:url];
//3.转换并显示数据
UIImage *image = [UIImage imageWithData:data];
self.imageView.image = image;
}
```
（2）第二种方式（NSURLConnection-sendAsync）
```objc
//使用NSURLConnection发送异步请求下载文件资源
-(void)connectDownload
{
//1.确定请求路径
NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/images/minion_01.png"];
//2.创建请求对象
NSURLRequest *request = [NSURLRequest requestWithURL:url];
//3.使用NSURLConnection发送一个异步请求
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
//4.拿到并处理数据
UIImage *image = [UIImage imageWithData:data];
self.imageView.image = image;
}];
}
```
（3）第三种方式（NSURLConnection-delegate）
```objc
//使用NSURLConnection设置代理发送异步请求的方式下载文件
-(void)connectionDelegateDownload
{
//1.确定请求路径
NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"];
//2.创建请求对象
NSURLRequest *request = [NSURLRequest requestWithURL:url];
//3.使用NSURLConnection设置代理并发送异步请求
[NSURLConnection connectionWithRequest:request delegate:self];
}
#pragma mark--NSURLConnectionDataDelegate
//当接收到服务器响应的时候调用，该方法只会调用一次
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
//创建一个容器，用来接收服务器返回的数据
self.fileData = http://www.mamicode.com/[NSMutableData data];
//获得当前要下载文件的总大小（通过响应头得到）
NSHTTPURLResponse *res = (NSHTTPURLResponse *)response;
self.totalLength = res.expectedContentLength;
NSLog(@"%zd",self.totalLength);
//拿到服务器端推荐的文件名称
self.fileName = res.suggestedFilename;
}
//当接收到服务器返回的数据时会调用
//该方法可能会被调用多次
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// NSLog(@"%s",__func__);
//拼接每次下载的数据
[self.fileData appendData:data];
//计算当前下载进度并刷新UI显示
self.currentLength = self.fileData.length;
NSLog(@"%f",1.0* self.currentLength/self.totalLength);
self.progressView.progress = 1.0* self.currentLength/self.totalLength;
}
//当网络请求结束之后调用
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
//文件下载完毕把接受到的文件数据写入到沙盒中保存
//1.确定要保存文件的全路径
//caches文件夹路径
NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
NSString *fullPath = [caches stringByAppendingPathComponent:self.fileName];
//2.写数据到文件中
[self.fileData writeToFile:fullPath atomically:YES];
NSLog(@"%@",fullPath);
}
//当请求失败的时候调用该方法
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
NSLog(@"%s",__func__);
}
```
#####5.0 大文件的下载
（1）实现思路
边接收数据边写文件以解决内存越来越大的问题
（2）核心代码
```objc
//当接收到服务器响应的时候调用，该方法只会调用一次
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
//0.获得当前要下载文件的总大小（通过响应头得到）
NSHTTPURLResponse *res = (NSHTTPURLResponse *)response;
self.totalLength = res.expectedContentLength;
NSLog(@"%zd",self.totalLength);
//创建一个新的文件，用来当接收到服务器返回数据的时候往该文件中写入数据
//1.获取文件管理者
NSFileManager *manager = [NSFileManager defaultManager];
//2.拼接文件的全路径
//caches文件夹路径
NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
NSString *fullPath = [caches stringByAppendingPathComponent:res.suggestedFilename];
self.fullPath = fullPath;
//3.创建一个空的文件
[manager createFileAtPath:fullPath contents:nil attributes:nil];
}
//当接收到服务器返回的数据时会调用
//该方法可能会被调用多次
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
//1.创建一个用来向文件中写数据的文件句柄
//注意当下载完成之后，该文件句柄需要关闭，调用closeFile方法
NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:self.fullPath];
//2.设置写数据的位置(追加)
[handle seekToEndOfFile];
//3.写数据
[handle writeData:data];
//4.计算当前文件的下载进度
self.currentLength += data.length;
NSLog(@"%f",1.0* self.currentLength/self.totalLength);
self.progressView.progress = 1.0* self.currentLength/self.totalLength;
}
```
ios开发网络学习三：NSURLConnection小文件大文件下载