NSFileManager类与文件操作

Posted 2022-01-29 亚洲小炫风

用于对文件与目录进行的多种操作的(创建,复制,重命名,删除等)

可以通过defaultManager类方法创建

-[NSFileManager defaultManager]

一些文件操作的概念:
-当前目录:.
-上级目录:..
-根目录 :/
-home目录 ~
-绝对路径:从根目录开始的路径
-相对路径:从当前目录开始的路径

常用的目录操作

1.获取当前目录:currentDirectoryPath
2.概念当前目录:changerCurrentDireactoryPath:path
3.创建目录:createDireactoryAtPath:path
4.复制目录(文件):copyItemAtPath:from toPath:to
5.移动目录(文件):moveItemAtPath:from toPath:to
6.删除目录(文件):removeItemAtPath:path

 NSFileManager *fileManager=[NSFileManager new];
    NSLog(@"=====>path:%@",  fileManager.currentDirectoryPath);
    [fileManager changeCurrentDirectoryPath:@".."];
    NSLog(@"=====>path:%@",  fileManager.currentDirectoryPath);
    
    //创建目录
    NSError *error=nil;
    NSString *dirPath=[NSHomeDirectory() stringByAppendingFormat:@"hello"];
    [fileManager createDirectoryAtPath:dirPath withIntermediateDirectories:NO attributes:nil error:&error];
    if(error==nil)
        [fileManager changeCurrentDirectoryPath:dirPath];
        NSLog(@"=====>path:%@",  fileManager.currentDirectoryPath);
    else
        NSLog(@"==========>error:%@",error);
    
    
    //删除目录
    if([fileManager removeItemAtPath:dirPath error:nil])
        NSLog(@"==========>删除成功");
    
    [fileManager createDirectoryAtPath:dirPath withIntermediateDirectories:NO attributes:nil error:nil];
    [fileManager createDirectoryAtPath:[NSHomeDirectory() stringByAppendingFormat:@"test"] withIntermediateDirectories:NO attributes:nil error:nil];
    
    NSDirectoryEnumerator<NSString *> *paths= [fileManager enumeratorAtPath:NSHomeDirectory()];
    NSString *path=nil;
    while(path=[paths nextObject])
    
        NSLog(@"=====>文件:%@",path);
    
   
    NSArray<NSString *> *path2= [fileManager contentsOfDirectoryAtPath:NSHomeDirectory() error:nil];
    for(NSString *path in path2)
    
        NSLog(@"=====>file:%@",path);
    

常用的文件操作
1.创建文件:crateFileAtPath:path contents:data attributes:attr
2.判断文件是否存在:filesExistsAtPath:path
3.判断两个文件内容是否一样:contentsEqualAtPath:andPath:
4.复制目录(文件):copyItemAtPath:from toPath:to
5.移动目录(文件):moveItemAtPath:from toPath:to
6.删除目录(文件):removeItemAtPath:path
7.获取目录(文件)属性
 NSDictionary *attr=[fm attributesOfItemAtPath:path];

 NSFileManager *manager=[NSFileManager defaultManager];
    NSString *content=@"hello world";
    NSData *data=[NSData dataWithBytes:[content UTF8String] length:content.length];

    NSString *path=[NSHomeDirectory() stringByAppendingFormat:@"/test.txt"];
    if([manager createFileAtPath:path contents:data attributes:nil])
        NSLog(@"创建成功");
    
    if([manager fileExistsAtPath:path])
        NSLog(@"=====>path:%@ 已经存在",path);
    
 
    NSArray<NSString *> *paths= [manager contentsOfDirectoryAtPath:NSHomeDirectory() error:nil];
    for(NSString *path in paths)
    
        NSLog(@"====>path:%@",path);
    

文件移动和属性
 

 NSFileManager *manager=[NSFileManager defaultManager];
    NSString *content=@"hello world";
    NSData *data=[NSData dataWithBytes:[content UTF8String] length:content.length];

    NSString *path=[NSHomeDirectory() stringByAppendingFormat:@"/test.txt"];
    if([manager createFileAtPath:path contents:data attributes:nil])
        NSLog(@"创建成功");
    
    if([manager fileExistsAtPath:path])
        NSLog(@"=====>path:%@ 已经存在",path);
    
 
    //移动文件:
    NSString *newPath=[NSHomeDirectory() stringByAppendingFormat:@"/test2.txt"];
    if([manager moveItemAtPath:path toPath:newPath error:nil])
        NSLog(@"=====>移动文件成功");
    
    NSArray<NSString *> *paths= [manager contentsOfDirectoryAtPath:NSHomeDirectory() error:nil];
    for(NSString *path in paths)
    
        NSLog(@"====>path:%@",path);
    
    
    //获取文件属性
    NSDictionary<NSFileAttributeKey, id> *attributes= [manager attributesOfItemAtPath:newPath error:nil];
    NSLog(@"=======>attributes:%@",attributes);
    /**
     =======>attributes:
         NSFileCreationDate = "2021-06-25 12:32:14 +0000";
         NSFileExtensionHidden = 0;
         NSFileGroupOwnerAccountID = 20;
         NSFileGroupOwnerAccountName = staff;
         NSFileModificationDate = "2021-06-25 12:32:14 +0000";
         NSFileOwnerAccountID = 501;
         NSFilePosixPermissions = 420;
         NSFileReferenceCount = 1;
         NSFileSize = 11;
         NSFileSystemFileNumber = 13287847;
         NSFileSystemNumber = 16777220;
         NSFileType = NSFileTypeRegular;
     */
    

数据缓冲区管理类
1.分为不可变(NSData)和可变的（NSMutableData)
2.与字符串的转换
NSString *str=@"this is a test file";
NSData *data=[str dataUsingEncoding:NSUTF8StringEncoding];
NSString *str2=[[NSString allow] initWithData encoding:NSUTF8Encoding];

从文件读取到缓冲区
NSData *data=[fm contentsAtPath:path];

从缓冲区写数据到文件
createFileAtPath:path contents:data attributes:attr

-(void)test
    NSFileManager *manager=  [NSFileManager defaultManager];
    NSString *path=[NSHomeDirectory() stringByAppendingFormat:@"/test2.txt"];
    NSString *str=@"我爱你\\n 你也爱我";
    NSData *content=[NSData dataWithBytes:[str UTF8String] length:str.length];
    if([manager createFileAtPath:path contents:content attributes:nil])
        NSLog(@"====>文件创建成功");
    

    //1. 通过创建NSFileHandle对象
    NSFileHandle *handle=[NSFileHandle fileHandleForReadingAtPath:path];
    //NSData *buffer=[handle readDataToEndOfFile];
    NSData *buffer=[handle readDataOfLength:str.length];
    NSString *fileStr=[[NSString alloc] initWithData:buffer encoding:NSUTF8StringEncoding];
    NSLog(@"=======>读取str:%@",fileStr);
    //3.
    [handle closeFile];
  

获取常用的特殊目录函数
1.返回当前用户的登录名
-NSString *NSUserName()
2.返回当前用户的完整用户名
-NSString *NSFullUserName()
3.返回当前用户主目录的路径
-NSString *NSHomeDirectory()
4.返回用户user的主目录
-NSString *NSHomeDirectoryForUser()
5.返回可用于创建临时文件的路径目录
-NSString *NSTemporayDirectory();