一、传统的下载文件的方式
- (void)downloaderWithUrl:(NSURL *)url
{
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request queue:[[NSOperationQueue alloc] init] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
if (!connectionError)
{
NSHTTPURLResponse *urlResponse = (NSHTTPURLResponse *)response;
if (urlResponse.statusCode == 200 || urlResponse.statusCode == 304)
{
[data writeToFile:@"/Users/gxiangzi/Desktop/a.mp4" atomically:YES];
NSLog(@"OK");
}
}else
{
NSLog(@"错误");
}
}];
}
但是这种方式存在着弊端:
1> 用不无法跟踪下载的进度，无法直观的显示下载进度
2> 文件下载的时候，都会先下载到内存之中，导致内存 > 所需文件的大小长度，会造成程序崩溃等现象(可以查看内存的耗费)
二、代理的方式下载程序(NSURLConnectionDownloadDelegate)
#import "GXDownloader.h"
@interface GXDownloader () <NSURLConnectionDownloadDelegate>
@end
@implementation GXDownloader
- (void)downloaderWithUrl:(NSURL*)url
{
NSURLRequest* request = [NSURLRequest requestWithURL:url];
[[NSURLConnection alloc] initWithRequest:request delegate:self];
}
#pragma mark - NSURLConnectionDownloadDelegate
/**
bytesWritten: 表示下载的数据字节数
totalBytesWritten:总的已经下载的字节数
expectedTotalBytes:期望的总的字节数
*/
- (void)connection:(NSURLConnection*)connection didWriteData:(long long)bytesWritten totalBytesWritten:(long long)totalBytesWritten expectedTotalBytes:(long long)expectedTotalBytes
{
float progress = (float)totalBytesWritten / expectedTotalBytes;
NSLog(@"%f", progress);
}
/**
* @param connection
* @param totalBytesWritten : 总的已经下载的字节数
* @param expectedTotalBytes : 期望总的字节数
*/
- (void)connectionDidResumeDownloading:(NSURLConnection*)connection totalBytesWritten:(long long)totalBytesWritten expectedTotalBytes:(long long)expectedTotalBytes
{
}
/**
* @param connection
* @param destinationURL:下载完的目标路径
*/
- (void)connectionDidFinishDownloading:(NSURLConnection*)connection destinationURL:(NSURL*)destinationURL
{
NSLog(@"%@", destinationURL);
}
优点：
1> 该种方式可以跟踪文件下载的进度；
2> 也可以解决内存消耗过大的问题
弊端： 这丫的 下载的文件没有 ，就是虽然你显示下载完成，但是你本地找不到该文件------没有任何卵用
三、第三种方式--代理(NSURLConnectionDataDelegate)
//
// GXDownloader.m
// 02-下载
//
// Created by gxiangzi on 15/8/21.
// Copyright (c) 2015年 hqu. All rights reserved.
//
#import "GXDownloader.h"
@interface GXDownloader () <NSURLConnectionDataDelegate>
// 文件的总长度
@property (nonatomic, assign) long long expectedContentLength;
// 已经接受到文件的长度
@property (nonatomic, assign) long long receivedContentLength;
// 已经接收到的文件的总长度
@property (nonatomic, strong) NSMutableData* receivedData;
@end
@implementation GXDownloader
- (void)downloaderWithUrl:(NSURL*)url
{
NSURLRequest* request = [NSURLRequest requestWithURL:url];
[[NSURLConnection alloc] initWithRequest:request delegate:self];
}
#pragma mark - NSURLConnectionDataDelegate
/**
* 已经接受到响应头
*/
- (void)connection:(NSURLConnection*)connection didReceiveResponse:(NSURLResponse*)response
{
self.expectedContentLength = response.expectedContentLength;
}
/**
* 文件接受到一点的时候就是用
*/
- (void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
{
// 把二进制数据进行拼接
[self.receivedData appendData:data];
// 拼接长度
self.receivedContentLength += data.length;
float progress = (float)self.receivedContentLength / self.expectedContentLength;
NSLog(@"下载进度: %.2f",progress);
}
/**
* 下载出错的时候调用
*/
- (void)connection:(NSURLConnection*)connection didFailWithError:(NSError*)error
{
}
/**
* 当下载完成的时候调用
*/
- (void)connectionDidFinishLoading:(NSURLConnection*)connection
{
NSLog(@"下载完成");
// IOS 的文件路径，只能讲软件操作的数据放在沙盒内
NSString *path = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
NSString *fileName = [path stringByAppendingPathComponent:@"love.mp4"];
NSLog(@"%@",fileName);
[self.receivedData writeToFile:fileName atomically:YES];
}
#pragma mark -懒加载
- (NSMutableData*)receivedData
{
if (!_receivedData) {
_receivedData = [NSMutableData data];
}
return _receivedData;
}
@end
优点:
1> 可以检测到进度的问题
2> 文件的写入的路径之中，文件可以存在
弊端：
占用的内存太大
为了解决上面的问题： 引入了NSHandle 和 NSOutputStream ------下一点 写入文件一点
四、NSHandle的使用
//
// GXDownloader.m
// 02-下载
//
// Created by gxiangzi on 15/8/21.
// Copyright (c) 2015年 hqu. All rights reserved.
//
#import "GXDownloader.h"
@interface GXDownloader () <NSURLConnectionDataDelegate>
// 文件的总长度
@property (nonatomic, assign) long long expectedContentLength;
// 已经接受到文件的长度
@property (nonatomic, assign) long long receivedContentLength;
@end
@implementation GXDownloader
- (void)downloaderWithUrl:(NSURL*)url
{
NSURLRequest* request = [NSURLRequest requestWithURL:url];
[[NSURLConnection alloc] initWithRequest:request delegate:self];
}
#pragma mark - NSURLConnectionDataDelegate
/**
* 已经接受到响应头
*/
- (void)connection:(NSURLConnection*)connection didReceiveResponse:(NSURLResponse*)response
{
self.expectedContentLength = response.expectedContentLength;
}
/**
* 文件接受到一点的时候就是用
*/
- (void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
{
// 拼接长度
self.receivedContentLength += data.length;
float progress = (float)self.receivedContentLength / self.expectedContentLength;
NSLog(@"%f",progress);
NSString* path = @"/Users/gxiangzi/Desktop/a.mp4";
NSFileHandle* handle = [NSFileHandle fileHandleForWritingAtPath:path];
// 如果handle 不会帮我们创建文件
if (handle == nil) {
[data writeToFile:path atomically:YES];
}
else {
//让offset指向文件的末尾,在末尾处追加数据
[handle seekToEndOfFile];
//写输入
[handle writeData:data];
//关闭 (等文件下载完成关闭更好)
[handle closeFile];
}
}
/**
* 当下载完成的时候调用
*/
- (void)connectionDidFinishLoading:(NSURLConnection*)connection
{
NSLog(@"下载完成");
}
@end
原理：下载一点数据 写一点数据
效果:能够达到占用很少内存
五、NSOutputStream的使用
//
// GXDownloader.m
// 02-下载
//
// Created by gxiangzi on 15/8/21.
// Copyright (c) 2015年 hqu. All rights reserved.
//
#import "GXDownloader.h"
@interface GXDownloader () <NSURLConnectionDataDelegate>
// 文件的总长度
@property (nonatomic, assign) long long expectedContentLength;
// 已经接受到文件的长度
@property (nonatomic, assign) long long receivedContentLength;
@property (nonatomic, strong) NSOutputStream* stream;
@end
@implementation GXDownloader
- (void)downloaderWithUrl:(NSURL*)url
{
NSURLRequest* request = [NSURLRequest requestWithURL:url];
[[NSURLConnection alloc] initWithRequest:request delegate:self];
}
#pragma mark - NSURLConnectionDataDelegate
/**
* 已经接受到响应头
*/
- (void)connection:(NSURLConnection*)connection didReceiveResponse:(NSURLResponse*)response
{
self.expectedContentLength = response.expectedContentLength;
NSString* path = @"/Users/gxiangzi/Desktop/a.mp4";
// 注意 此处的url 为本地的路径
// 前面加 file:// 无效
// 只能使用 [NSURL fileURLWithPath:path]
self.stream = [NSOutputStream outputStreamWithURL:[NSURL fileURLWithPath:path] append:YES];
[self.stream open];
}
/**
* 文件接受到一点的时候就是用
*/
- (void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
{
// 拼接长度
self.receivedContentLength += data.length;
float progress = (float)self.receivedContentLength / self.expectedContentLength;
NSLog(@"%f", progress);
[self.stream write:data.bytes maxLength:data.length];
}
/**
* 当下载完成的时候调用
*/
- (void)connectionDidFinishLoading:(NSURLConnection*)connection
{
NSLog(@"下载完成");
[self.stream close];
}
- (NSOutputStream *)stream
{
if (_stream == nil)
{
_stream = [[NSOutputStream alloc] init];
}
return _stream;
}
@end
时间： 2024-12-20 23:29:17