iOS - 文件操作(File Operating)
1. 沙盒 & NSData
/*_______________________________获取沙盒路径_________________________________________*/
//第一种获取方式
//NSHomeDirectory();获取到沙盒的目录路径
NSString *homePath = NSHomeDirectory();
NSLog(@"沙盒目录:%@",homePath);
NSString *docPath1 = [NSString stringWithFormat:@"%@/Documents",homePath];
NSString *docPath2 = [homePath stringByAppendingString:@"/Documents"];
NSLog(@"\ndocPath1:%@,\ndocPath2:%@",docPath1,docPath2);
//第二种获取方式.
/*
NSDocumentDicrectory: Documents文件夹
NSLibraryDirectory : Library文件夹
*/
/*
NSArray *array = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSLog(@"array:%@",array);
2. 沙盒 & NSData & NSFileManager
(NSFileManager:文件的创建、复制、删除、前切文件（注意:操作对象为文件，而不是文件内容）。)
//演示路径
NSString *path = @"/Users/apple/file.text";
//1.返回路径的组成部分
NSArray *array = [path pathComponents];
NSLog(@"pathComponents:%@",array);
//2.路径的最后组成部分
NSString *lastPathComponent = [path lastPathComponent];
NSLog(@"lastComponent:%@",lastPathComponent);
//3.追加子路径
NSString *newPath1 = [path lastPathComponent];
NSLog(@"newPath1=%@",newPath1);
NSString *newPath2 = [path stringByAppendingPathComponent:@"/appFile.text"];
NSLog(@"newPath2:%@",newPath2);
//4.删除最后的组成部分
NSString *deleteLast = [path stringByDeletingLastPathComponent];
NSLog(@"deleteLast:%@",deleteLast);
//5.删除扩展名
NSString *deleteExtension = [path stringByDeletingPathExtension];
NSLog(@"deleteExtension:%@",deleteExtension);
//6.获取路径最后组成部分的扩展名
NSString *extension =[path pathExtension];
NSLog(@"extension:%@",extension);
//7.追加扩展名
NSString *appendExt = [path stringByAppendingPathExtension:@"jpg"];
NSLog(@"appendExt:%@",appendExt);
//NSString->NSData
NSString *s = @"tsdfsdfsdfsdf";
NSData *data = [s dataUsingEncoding:NSUTF8StringEncoding];
//NSData->NSString
NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"str:%@",str);
//NSMutableData 可变的Data对象，可以追加数据
3. 沙盒 & NSData & NSFileManager
(NSFileManger:文件的创建、复制、删除、剪切文件（注意:操作对象为文件，而不是文件内容）)
/*___________________________________1.创建文件_____________________________________*/
/*
//获取当前app的沙盒目录
NSString *homePath = NSHomeDirectory();
//追加子路径
NSString *filePath = [homePath stringByAppendingPathComponent:@"Documents/file.text"];
//NSFileManager不能使用alloc创建，这个类设计为单例
NSFileManager *fileManager1 = [NSFileManager defaultManager];
NSFileManager *fileManager2 = [NSFileManager defaultManager];
NSLog(@"f1=%p,f2=%p",fileManager1,fileManager2); //观察地址，发现相同
//NSFileManager只能通过类方法defaultManager创建
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *string = @"自动化测试部";
//将NSString 转化为 NSData对象.
NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
//根据路径filePath创建对应的文件，注意:只能创建文件，不能创建目录(文件夹).
BOOL success = [fileManager createFileAtPath:filePath contents:data attributes:nil];
if (success) {
NSLog(@"文件创建成功");
}else {
NSLog(@"文件创建失败");
}
//创建文件夹
NSString *filePath2 = [homePath stringByAppendingPathComponent:@"Documents/demo"];
NSError *error;
BOOL success2 = [fileManager createDirectoryAtPath:filePath2 withIntermediateDirectories:YES attributes:nil error:&error];
if (!success2) {
NSLog(@"创建失败:%@",error);
}
*/
/*___________________________________2.读取文件_____________________________________*/
/*
//获取当前app的沙盒根目录
NSString *homePath = NSHomeDirectory();
//追加子路径
NSString *filePath = [homePath stringByAppendingPathComponent:@"Documents/file.text"];
NSFileManager *fileManager = [NSFileManager defaultManager];
//根据路径读取文件中的数据
NSData *data = [fileManager contentsAtPath:filePath];
//NSData 转 NSString
NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"%@",string);
*/
/*___________________________________3.移动(前切)文件_____________________________________*/
/*
//获取当前app的沙盒根目录
NSString *homePath = NSHomeDirectory();
//源路径
NSString *filePath = [homePath stringByAppendingPathComponent:@"Documents/file.text"];
//目标路径
NSString *targetPath = [homePath stringByAppendingPathComponent:@"Documents/demo/file2.text"];
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOL success = [fileManager moveItemAtPath:filePath toPath:targetPath error:nil];
if (!success) {
NSLog(@"移动失败");
}
//一个思考:怎么实现给移动至此的文件改名字?? Method:通过剪切，文件从当前目录移动至当前目录
*/
/*___________________________________4.复制文件_____________________________________*/
/*
//获取当前app的沙盒目录
NSString *hoemPath = NSHomeDirectory();
//源路径
NSString *filePath = [hoemPath stringByAppendingPathComponent:@"Documents/demo/file3.text"];
//目标路径
NSString *targetPath = [hoemPath stringByAppendingPathComponent:@"Documents/file.text"];
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOL success = [fileManager copyItemAtPath:filePath toPath:targetPath error:nil];
if (!success) {
NSLog(@"复制失败");
}
*/
/*___________________________________3.删除文件_____________________________________*/
/*
//获取当前app的沙盒目录
NSString *hoemPath = NSHomeDirectory();
//源路径
NSString *filePath = [hoemPath stringByAppendingPathComponent:@"Documents/demo/file3.text"];
NSFileManager *fileManager = [NSFileManager defaultManager];
//判断文件是否存在
BOOL fileExist = [fileManager fileExistsAtPath:filePath];
if (fileExist) {
//removeItemAtPath:删除文件.
BOOL success = [fileManager removeItemAtPath:filePath error:nil];
if (success) {
NSLog(@"删除成功");
}
*/
/*___________________________________4.获取文件的属性_____________________________________*/
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *homePath = NSHomeDirectory();
//目标路径
NSString *filePath = [homePath stringByAppendingPathComponent:@"Documents/file.text"];
//获取到文件的属性
NSDictionary *fileAttr = [fileManager attributesOfItemAtPath:filePath error:nil];
NSLog(@"%@",fileAttr);
NSNumber *fileSize = [fileAttr objectForKey:NSFileSize];
long sizeValue = [fileSize longValue];
NSLog(@"文件大小:%ld",sizeValue);
//如下读取文件的大小不可取，因为将文件中的数据全都读到内存中，文件大时，太占内存了。
//NSData *data = [fileManager contentsAtPath:filePath];
//NSInteger len = data.length;
4. 读写文件 & NSFileHandle -文件内容操作
(Attention:NSFileHandle区别NSFileManager(主要对目录操作),NSFileHandle(主要对文件内容操作))
/*_______________________________NSString读、写文件__________________________________________*/
/*
//1.NSString写文件
NSString *s = @"自动化测试部门";
//文件路径
NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/filetext"];
//将字符串写入文件
BOOL success = [s writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:nil];
if (success) {
NSLog(@"字符串写入成功");
}
//2.NSString读文件
//创建字符串时同时读取文件路径对应的文件中的内容
NSString *string = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
NSLog(@"string=%@",string);
*/
/*_______________________________NSData读、写文件__________________________________________*/
/*
//1.NSData读文件
//文件路径
NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/file.text"];
//创建NSData时，同时读取文件中的内容
NSData *data = [[NSData alloc] initWithContentsOfFile:path];
NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"%@",string);
//2.NSData写文件
//[data writeToFile:<#(nonnull NSString *)#> atomically:<#(BOOL)#>]
*/
/*
注意:NSArray、NSDictionary 中只能存放NSNumber、NSString、NSData、NSDate、NSArray、NSDictionary
才能成功写入文件、写入文件我们成之为“属性列表文件”
*/
/*_______________________________NSArray读、写文件__________________________________________*/
//1.NSArray写文件
/*
NSString *s1 = @"zhangsan";
NSString *s2 = @"李四";
//文件路径
NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/array.plist"];
NSLog(@"path:%@",path);
NSArray *array = [[NSArray alloc] initWithObjects:s1,s2, nil];
BOOL success = [array writeToFile:path atomically:YES];
if (success) {
NSLog(@"写入成功");
}
*/
//数组、字典存入能存入NSNumber、NSData、NSDate、NSArray、NSDictionary以外的对象，则无法写入文件
/*
Person *p = [[Person alloc] init];
NSArray *array2 = [NSArray arrayWithObjects:p,@"demo", nil];
NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/array2.plist"];
BOOL success2 = [array2 writeToFile:path atomically:YES];
if (!success2) {
NSLog(@"写入失败");
}
*/
/*
//2.NSArray读文件
NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/array.plist"];
// NSString *path1 = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Property List.plist"];
NSArray *readArray = [[NSArray alloc] initWithContentsOfFile:path];
for (NSString *s in readArray) {
NSLog(@"s = %@",s);
}
*/
/*_______________________________NSDictionary读、写文件__________________________________________*/
//1.NSDictionary写入文件
NSDictionary *dic = @{
@"name":@"jack",
@"birthday":[NSDate date],
@"age":@22
};
NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/dic.plist"];
BOOL success = [dic writeToFile:path atomically:YES];
if (success) {
NSLog(@"写入成功");
}
//2.NSDictionary读文件
NSDictionary *readDic = [NSDictionary dictionaryWithContentsOfFile:path];
NSLog(@"readDic:%@",readDic);
5. 追加数据与定位读取
/*_____________________________________1.追加数据_____________________________________*/
/*
NSString *s = @"MLB-AE-SW";
//当前登陆用户的主目录
NSString *homePath = NSHomeDirectory();
NSString *path = [homePath stringByAppendingPathComponent:@"file.text"];
//写入文件
[s writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:nil];
*/
/*
NSString *homePath = NSHomeDirectory();
NSString *path = [homePath stringByAppendingPathComponent:@"file.text"];
//创建一个写入的NSFileHandle对象
NSFileHandle *writeHandle = [NSFileHandle fileHandleForWritingAtPath:path];
//将文件的偏移量设置到末尾,写入文件时则从末尾开始写入
[writeHandle seekToEndOfFile];
NSString *appendString = @"追加的数据";
NSData *data = [appendString dataUsingEncoding:NSUTF8StringEncoding];
//从当前偏移量开始写入数据
[writeHandle writeData:data];
//关闭文件
[writeHandle closeFile];
*/
/*_____________________________________2.定位读取_____________________________________*/
//当前登陆用户主目录
NSString *homePath = NSHomeDirectory();
NSString *path = [homePath stringByAppendingPathComponent:@"Documents/file.text"];
//通过NSFileManager获取文件大小
NSFileManager *fileManager = [NSFileManager defaultManager];
NSDictionary *fileAttr = [fileManager attributesOfItemAtPath:path error:nil];
NSNumber *fileSize = [fileAttr objectForKey:NSFileSize];
long long sizeValue = [fileSize longLongValue];
NSFileHandle *readHandle = [NSFileHandle fileHandleForReadingAtPath:path];
//将偏移量设置到中间位置
[readHandle seekToFileOffset:sizeValue/2];
//从当前偏移量读取到文件的末尾
NSData *data = [readHandle readDataToEndOfFile];
//NSData ---> NSString
NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"%@",string);
6. NSFileHandle实现复制文件的功能
NSString *homePath = NSHomeDirectory();
NSString *srcPath = [homePath stringByAppendingPathComponent:@"06 第六课 文件管理.pdf"];
//目标文件路径
NSString *targetPath = [homePath stringByAppendingPathComponent:@"Documents/06 第六课 文件管理.pdf"];
/*
注意:使用NSFileHandle只能读写译经存在的文件，不能创建文件
使用NSFileManager创建文件
*/
NSFileManager *fileManager = [NSFileManager defaultManager];
//创建目标文件
BOOL success = [fileManager createFileAtPath:targetPath contents:nil attributes:nil];
if (success) {
NSLog(@"目标文件创建成功!");
}
//创建用于读取文件的NSFileHandle对象
NSFileHandle *readHandle = [NSFileHandle fileHandleForReadingAtPath:srcPath];
//创建用于写入的NSFileHandle对象
NSFileHandle *writerHande = [NSFileHandle fileHandleForWritingAtPath:targetPath];
//从当前偏移量读到文件的末尾，偏移量默认是起始位置
//NSData *data = [readHandle readDataToEndOfFile];
//同上
NSData *data = [readHandle availableData]; //缺陷：每次读取文件全部内容(当文件很大时，程序就会crash)
//解决方式:一次读几个字节，一段一段的读.
//将数据写入目标文件
[writerHande writeData:data];
//关闭文件
[readHandle closeFile];
[writerHande closeFile];
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