对NSURLConnection的简单封装

ゞ浴缸里的玫瑰 2022-08-10 00:39 185阅读 0赞

\#import <Foundation/Foundation.h>  
  
@class YGFileDownloader;  
@protocol YGFileDownloaderDelegate <NSObject>  
  
\-(void)fileDownloader:(YGFileDownloader \*)downloader downloadSize:(unsigned long long)downloadSize totalSize:(unsigned long long)totalSize;  
\-(void)fileDownloaderDidFinishLoad;  
\-(void)fileDownloaderFailWithError:(NSError \*)error;  
  
@end  
  
@interface YGFileDownloader : NSObject  
  
@property (nonatomic,weak) id<YGFileDownloaderDelegate> delegate;  
  
\+(instancetype)sharedInstance;  
\-(void)start:(NSString \*)urlStr;  
\-(void)stop;  
  
@end

\#import "YGFileDownloader.h"  
\#import "NSString+util.h"  
  
@interface YGFileDownloader () <NSURLConnectionDataDelegate>  
  
@property (nonatomic,strong) NSURLConnection \*connection;  
@property (nonatomic,copy) NSString \*downloadDocPath;//这个路径标识我们下载的文件所存储的那个目录，他是写死的，每次下载东西都能放在目录下面  
@property (nonatomic,strong) NSFileHandle \*fileHandle;  
@property (nonatomic) unsigned long long downloadFileSize;//当前下载了多少（字节）  
@property (nonatomic) unsigned long long totalFileSize;//文件总大小  
  
@end  
  
@implementation YGFileDownloader  
  
\-(NSString \*)downloadDocPath\{  
    if (\_downloadDocPath==nil) \{  
        //找到沙盒的Document目录  
        NSString \*documentPath=\[NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES) objectAtIndex:0\];  
        //上面这句代码和 \[NSHomeDirectory()stringByAppendingPathComponent:@"Documents"\];一样  
        NSString \*downloadPath=\[documentPath stringByAppendingPathComponent:@"YGFileDownload"\];  
        BOOL isSuccess=\[\[NSFileManager defaultManager\] createDirectoryAtPath:downloadPath withIntermediateDirectories:YES attributes:nil error:nil\];  
        if (isSuccess) \{  
            NSLog(@"创建文件夹成功");  
        \}  
        \_downloadDocPath=downloadPath;  
  
    \}  
    return \_downloadDocPath;  
\}  
  
\+(instancetype)sharedInstance\{//创建单例对象  
    static YGFileDownloader \*downloader=nil;  
    static dispatch\_once\_t onceToken;  
    dispatch\_once(&onceToken,^\{//大括号里的代码只会执行一次  
        downloader=\[\[YGFileDownloader alloc\] init\];  
    \});  
    return downloader;  
\}  
  
\-(void)start:(NSString \*)urlStr\{  
    NSString \*fullPath=\[self prepareStart:urlStr\];  
    //获取fullPath标识的文件的大小  
    \_downloadFileSize=\[self readDownloadFileSize:fullPath\];  
      
    NSMutableURLRequest \*request=\[\[NSMutableURLRequest alloc\] initWithURL:\[NSURL URLWithString:urlStr\]\];  
    \[request addValue:\[NSString stringWithFormat:@"bytes=%llu-",\_downloadFileSize\] forHTTPHeaderField:@"Range"\];//告诉服务器请求\_downloadFileSize以后的字节  
    self.connection=\[\[NSURLConnection alloc\] initWithRequest:request delegate:self\];  
      
\}  
\-(NSString \*)prepareStart:(NSString \*)urlStr\{//确保urlStr所对应的沙盒的位置上有文件  
    NSString \*fileName=urlStr.md5;//把url所对应的MD5值作为文件名  
      
    //fullPath代表这个文件具体的位置（路径）  
    NSString \*fullPath=\[self.downloadDocPath stringByAppendingString:fileName\];  
      
    //如果指定的这个路径下面不存在这个文件，我们就把他创建出来  
    BOOL fileExists=\[\[NSFileManager defaultManager\] fileExistsAtPath:fullPath\];  
    if (!fileExists) \{  
        \[\[NSFileManager defaultManager\] createFileAtPath:fullPath contents:nil attributes:nil\];  
    \}  
      
    //打开这个文件准备往里面写数据  
    self.fileHandle=\[NSFileHandle fileHandleForWritingAtPath:fullPath\];  
      
    return fullPath;  
    //这个函数的功能是在准备下载文件之前做一些准备工作：1.确保文件存在，2.打开文件准备往里面写数据，3.获取这个文件的确切路径，因为我们在往这个路径所标识的这个文件中写数据（我们下载的数据）  
\}  
\-(unsigned long long)readDownloadFileSize:(NSString \*)filePath\{//读取filePath文件的文件大小  
    NSDictionary \*fileInfo=\[\[NSFileManager defaultManager\] attributesOfItemAtPath:filePath error:nil\];  
    return \[fileInfo fileSize\];  
\}  
  
  
\-(void)stop\{  
    \[\_connection cancel\],\_connection=nil;  
    \[\_fileHandle closeFile\],\_fileHandle=nil;  
\}  
  
\#pragma mark - <NSURLConnectionDataDelegate>  
\-(void)connection:(NSURLConnection \*)connection didReceiveResponse:(NSURLResponse \*)response\{  
    \_totalFileSize=\_downloadFileSize+response.expectedContentLength;  
\}  
\-(void)connection:(NSURLConnection \*)connection didFailWithError:(NSError \*)error\{  
    if (\[self.delegate conformsToProtocol:@protocol(YGFileDownloaderDelegate)\]&&\[self.delegate respondsToSelector:@selector(fileDownloaderFailWithError:)\]) \{  
        \[self.delegate fileDownloaderFailWithError:error\];  
    \}  
\}  
\-(void)connectionDidFinishLoading:(NSURLConnection \*)connection\{  
    if (\[self.delegate respondsToSelector:@selector(fileDownloaderDidFinishLoad)\]) \{  
        \[self.delegate fileDownloaderDidFinishLoad\];  
    \}  
\}  
\-(void)connection:(NSURLConnection \*)connection didReceiveData:(NSData \*)data\{  
    \[\_fileHandle seekToEndOfFile\];//设置在末尾追加数据  
    \[\_fileHandle writeData:data\];//写入数据  
    \_downloadFileSize += data.length;  
    if (\[self.delegate conformsToProtocol:@protocol(YGFileDownloaderDelegate)\] && \[self.delegate respondsToSelector:@selector(fileDownloader:downloadSize:totalSize:)\]) \{  
        \[self.delegate fileDownloader:self downloadSize:\_downloadFileSize totalSize:\_totalFileSize\];  
    \}  
\}  
  
@end