OC中文件读取类(NSFileHandle)介绍和常用使用方法

NSFileHandle

1.NSFileManager类主要对于文件的操作(删除，修改，移动，赋值等等)

    //判断是否有 tagetPath 文件路径，没有就创建

    NSFileManager *fileManage = [NSFileManager defaultManager];

    BOOL success = [fileManage createFileAtPath:tagetPath contents:nil attributes:nil];

    if (success) {

    NSLog(@"create success");

    }

2.NSFileHandle类主要对文件的内容进行读取和写入操作

①NSFileHandle处理文件的步骤

1:创建一个NSFileHandle对象

    //创建流
    NSFileHandle *inFileHandle = [NSFileHandle fileHandleForReadingAtPath:srcPath];

    NSFileHandle *outFileHandle = [NSFileHandle fileHandleForWritingAtPath:tagetPath];

2:对打开的文件进行I/O操作

    //获取文件路径
    NSString *homePath = NSHomeDirectory();

    NSString *filePath = [homePath stringByAppendingPathComponent:@"phone/Date.text"];

    NSFileHandle *fileHandle = [NSFileHandle fileHandleForUpdatingAtPath:filePath];

　//定位到最后
 　[fileHandle seekToEndOfFile];

 　//定位到某个位置，100字节之后
    [fileHandle seekToFileOffset:100];

   //追加的数据
    NSString *str = @"add world";

    NSData *stringData = [str dataUsingEncoding:NSUTF8StringEncoding];

    //追加写入数据
    [fileHandle writeData:stringData];

3:关闭文件对象操作

　　//关闭流
    [fileHandle closeFile];

常用处理方法，读

//读取文件内容
void readByFile(){

    //文件路径
    NSString *homePath = NSHomeDirectory();

    NSString *filePath = [homePath stringByAppendingPathComponent:@"phone/cellPhone.text"];
    NSFileHandle *fileHandle = [NSFileHandle fileHandleForReadingAtPath:filePath];
    NSInteger length = [fileHandle availableData].length;

    //跳转到指定位置
    [fileHandle seekToFileOffset:length/2];
    NSData *data = [fileHandle readDataToEndOfFile];
    NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"%@",str);

    [fileHandle closeFile];

}

复制文件

void copy2Other(){
    NSString *homePath = NSHomeDirectory();
    NSString *filePath = [homePath stringByAppendingPathComponent:@"phone/cellPhone.text"];
    NSString *tagetPath = [homePath stringByAppendingPathComponent:@"phone/cellPhone_bak.text"];

    //是否有这个文件，没有则创建
    NSFileManager *fileManage =[NSFileManager defaultManager];
    BOOL success = [fileManage createFileAtPath:tagetPath contents:nil attributes:nil];
    if (success) {
        NSLog(@"create success");
    }

    //通过 NSFileHandle 读取源文件,写入另一文件中
    NSFileHandle *outFileHandle = [NSFileHandle fileHandleForWritingAtPath:tagetPath];
    NSFileHandle *inFileHandle = [NSFileHandle fileHandleForReadingAtPath:filePath];
    NSData *data = [inFileHandle readDataToEndOfFile];
    [outFileHandle writeData:data];

    //关闭流
    [inFileHandle closeFile];
    [outFileHandle closeFile];
}