文件下载
- 4.1 小文件下载
(1)第一种方式(NSData)
//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 = [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)
//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)
//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 = [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__);
}