源码0603-01-了解-大文件下载（NSOutputStream）

最新推荐文章于 2019-06-06 06:16:21 发布

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最新推荐文章于 2019-06-06 06:16:21 发布

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原文链接：http://www.cnblogs.com/laugh/p/6610855.html

本文介绍了如何使用NSOutputStream进行大文件下载，通过NSURLConnection与RunLoop的结合实现后台下载任务。文章详细展示了如何设置NSURLConnection代理并利用NSOutputStream将数据写入文件。

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NSOutputStream 数据流的使用

//  ViewController.m
//  01-了解-大文件下载（NSOutputStream）

#import "ViewController.h"

@interface ViewController () <NSURLConnectionDataDelegate>
/** 输出流对象 */
@property (nonatomic, strong) NSOutputStream *stream;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [NSURLConnection connectionWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"]] delegate:self];
}

#pragma mark - <NSURLConnectionDataDelegate>
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    // response.suggestedFilename : 服务器那边的文件名
    
    // 文件路径
    NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
    NSString *file = [caches stringByAppendingPathComponent:response.suggestedFilename];
    NSLog(@"%@", file);
    
    // 利用NSOutputStream往Path中写入数据（append为YES的话，每次写入都是追加到文件尾部）
    self.stream = [[NSOutputStream alloc] initToFileAtPath:file append:YES];
    // 打开流(如果文件不存在，会自动创建)
    [self.stream open];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [self.stream write:[data bytes] maxLength:data.length];
    NSLog(@"didReceiveData-------");
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    [self.stream close];
    NSLog(@"-------");
}

@end

//  ViewController.m
//  03-NSURLConnection与RunLoop
#import "ViewController.h"

@interface ViewController () <NSURLConnectionDataDelegate>
/** runLoop */
@property (nonatomic, assign) CFRunLoopRef runLoop;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        NSURLConnection *conn = [NSURLConnection connectionWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://120.25.226.186:32812/resources/images/minion_01.png"]] delegate:self];
        // 决定代理方法在哪个队列中执行
        [conn setDelegateQueue:[[NSOperationQueue alloc] init]];
        
        // 启动子线程的runLoop
//        [[NSRunLoop currentRunLoop] run];
        
        self.runLoop = CFRunLoopGetCurrent();
        
        // 启动runLoop
        CFRunLoopRun();
    });
}

#pragma mark - <NSURLConnectionDataDelegate>
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"didReceiveResponse----%@", [NSThread currentThread]);
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    
    NSLog(@"didReceiveData----%@", [NSThread currentThread]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"connectionDidFinishLoading----%@", [NSThread currentThread]);
    
    // 停止RunLoop
    CFRunLoopStop(self.runLoop);
}

@end