02-IOSCore - NSFileHandle、合并文件、文件指针、文件查看器

【day0201_NSFileHandle】：文件句柄

1 NSFileHandle 文件对接器、文件句柄

常用API:

- (NSData *)readDataToEndOfFile;读取数据到最后

- (NSData *)readDataOfLength:(NSUInteger)length; 读取长度

- (void)writeData:(NSData *)data; 写数据

- (unsignedlonglong)seekToEndOfFile; 将文件指针移至最后，并返回文件长度

- (void)seekToFileOffset:(unsignedlonglong)offset; 指定文件指针位置

- (void)closeFile; 关闭文件，一般写完/读完数据要关闭文件

+ (id)fileHandleForReadingAtPath:(NSString *)path; 根据路径读取数据

+ (id)fileHandleForWritingAtPath:(NSString *)path; 根据路径写数据

案例代码：

/*

写入：NSString -> 文件

读取：文件 -> NSString

*/

- (void)viewDidLoad

{

[superviewDidLoad];

NSString *homePath = NSHomeDirectory();

NSLog(@"%@",homePath);

NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];

NSString *filePath = [documentsPath stringByAppendingPathComponent:@"hello.txt"];

NSString *fileContent = @"你好";

// 写入：

// 怎么把fileContent写到hello.txt呢

// 先把fileContent->NSData  ,  然后写到hello.txt中

// NSString -> NSData

NSData *data = [fileContent dataUsingEncoding:NSUTF8StringEncoding];

// NSData -> 文件完整步骤

// 准备空文件hello.txt

NSFileManager *fileManager = [NSFileManagerdefaultManager];

[fileManager createFileAtPath:filePath contents:nilattributes:nil];

// 创建文件对接器

NSFileHandle *fileHandle = [NSFileHandlefileHandleForWritingAtPath:filePath];

// 写入数据

[fileHandle writeData:data];

// 关闭文件对接器

[fileHandle closeFile];

// 写入文件还有更快捷的方法

//    [fileManager createFileAtPath:filePath contents:data attributes:nil];

// 读取

// 文件 -> NSData -> NSString

// 创建文件对接器

NSFileHandle *readHandle = [NSFileHandlefileHandleForReadingAtPath:filePath];

// 读数据

NSData *data1 = [readHandle readDataToEndOfFile];

// 关闭对接器

[readHandle closeFile];

// data -> string

NSString *str = [[NSStringalloc] initWithData:data1 encoding:NSUTF8StringEncoding];

NSLog(@"%@",str);

// string根据路径可以直接获取数据

NSString *str2 = [NSStringstringWithContentsOfFile:filePath encoding:NSUTF8StringEncodingerror:nil]; // 读取文件以UTF8显示

// 识别编码

NSStringEncoding encode;

NSString *str3 = [NSStringstringWithContentsOfFile:filePath usedEncoding:&encode error:nil]; // 该方法做了两件事，首先根据路径读取数据，然后把该数据的编码赋值给encode

NSLog(@"%d",encode); // 4 表示UTF8编码

}

【day0202_copyFileContent】：copy文件

练习：

先用NSString -> 文件

往Documents下写一个文件source.txt

文件的内容随便，有中文

需要写代码拷贝文件 -> copy .txt

源文件 -> NSData-> 新文件

FileHandle   NSData

- (void)viewDidLoad

{

[superviewDidLoad];

NSLog(@"%@",NSHomeDirectory());

NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDirectory, YES)[0];

NSString *filePath = [documentsPath stringByAppendingPathComponent:@"sourcefile.txt"];

NSData *data = [@"中文!"dataUsingEncoding:NSUTF8StringEncoding];

[[NSFileManagerdefaultManager] createFileAtPath:filePath contents:nilattributes:nil];

[[NSFileManagerdefaultManager] createFileAtPath:filePath contents:data attributes:nil];

// 文件 -> data

NSFileHandle *readHandle = [NSFileHandlefileHandleForReadingAtPath:filePath];

NSData *dataFromFile = [readHandle readDataToEndOfFile];

// data -> 新文件copy.txt

NSString *copyPath = [documentsPath stringByAppendingPathComponent:@"copy.txt"];

[[NSFileManagerdefaultManager] createFileAtPath:copyPath contents:dataFromFile attributes:nil];

// copy图片

NSData *picData = [NSDatadataWithContentsOfFile:@"/Users/.../01.jpg"];

NSString *picPath = [documentsPath stringByAppendingPathComponent:@"01.jpg"];

[[NSFileManagerdefaultManager] createFileAtPath:picPath contents:picData attributes:nil];

}

【day0203_merge合并文件】

合并一些文件的内容到新文件中

- (void)viewDidLoad

{

[superviewDidLoad];

NSLog(@"%@",NSHomeDirectory());

// 获取documents路径

NSString *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];

// 源文件名数组

NSArray *sourceNames = @[@"a.txt", @"b.txt", @"c.txt",];

// 合并文件名

NSString *outputName = @"combine.txt";

// 合并文件路径

NSString *outputFilePath = [documents stringByAppendingPathComponent:outputName];

// 创建合并文件

[[NSFileManagerdefaultManager] createFileAtPath:outputFilePath contents:nilattributes:nil];

// 创建filehandle

NSFileHandle *writeHandle = [NSFileHandlefileHandleForWritingAtPath:outputFilePath];

// 循环写入数据

for (NSString *sourceName in sourceNames) {

NSString *sourceFilePath = [documents stringByAppendingPathComponent:sourceName]; // 源文件路径

NSFileHandle *readHandle = [NSFileHandlefileHandleForReadingAtPath:sourceFilePath]; // 创建读取handle

NSData *readData = [readHandle readDataToEndOfFile]; // 读出数据

[writeHandle writeData:readData]; // 写到新文件中

[readHandle closeFile]; // 关闭读取文件

}

// 关闭文件

[writeHandle closeFile];

}

【day0204_FilePointer文件指针】

文件指针的使用

按指定字节拷贝文件

- (void)viewDidLoad

{

[superviewDidLoad];

NSLog(@"%@",NSHomeDirectory());

NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];

NSString *sourcePath = [documentsPath stringByAppendingPathComponent:@"source.txt"];

// 按每次1000字节的中专拷贝一张图片

NSString *picPath = @"/Users/tarena/yz/第三阶段(UI核心_Model赵哲)/day02/1-4.jpg";

// 拷贝

// 创建读取handle

NSFileHandle *readHandle = [NSFileHandlefileHandleForReadingAtPath:picPath];

unsignedlonglong picSize = [readHandle seekToEndOfFile]; // 图片大小

unsignedlonglong offset = 0;

NSString *path = [documentsPath stringByAppendingPathComponent:@"0.jpg"]; // document下图片路径

[[NSFileManagerdefaultManager] createFileAtPath:path contents:nilattributes:nil]; // 创建空jpg文件

NSFileHandle *writeHandle = [NSFileHandlefileHandleForWritingAtPath:path]; // 创建写handle

[readHandle seekToFileOffset:0]; // 设置文件指针

// 循环读取文件写入到document下空的jpg文件

NSData *data = nil;

while (offset + 1000 <= picSize) { // 一次读1000

data = [readHandle readDataOfLength:1000];

[writeHandle writeData:data];

offset += 1000;

NSLog(@"%llu",offset);

}

// 不足1000的读到最后

data = [readHandle readDataToEndOfFile];

[writeHandle writeData:data];

[readHandle closeFile];

[writeHandle closeFile];

// 文件指针的使用

NSFileHandle *readHandle = [NSFileHandle fileHandleForReadingAtPath:sourcePath];

unsignedlonglong fileSize = [readHandle seekToEndOfFile]; // 该方法会把文件指针移至最后并返回文件大小

NSLog(@"%llu",fileSize);

[readHandle seekToFileOffset:0]; // 设置指针位置

NSData *data = [readHandle readDataOfLength:3]; // 读取长度以字节为单位一个汉子占3个字节

NSString *str = [[NSStringalloc] initWithData:data encoding:NSUTF8StringEncoding];

NSLog(@"%@",str);

[readHandle closeFile];

}

【day0205_文件查看器】

MXDocumentsViewController.m

- (void)viewDidLoad

{

[superviewDidLoad];

if (!self.path) {

self.path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];

}

NSArray *fileNameArray = [[NSFileManagerdefaultManager] contentsOfDirectoryAtPath:self.patherror:nil];

self.files = [NSMutableArrayarray];

for (NSString *fileName in fileNameArray) {

NSString *filePath = [self.pathstringByAppendingPathComponent:fileName];

[self.filesaddObject:filePath];

}

NSLog(@"%@",self.files);

// Uncomment the following line to preserve selection between presentations.

// self.clearsSelectionOnViewWillAppear = NO;

// Uncomment the following line to display an Edit button in the navigation bar for this view controller.

// self.navigationItem.rightBarButtonItem = self.editButtonItem;

}

- (void)didReceiveMemoryWarning

{

[superdidReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

#pragma mark - Table view data source

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

{

returnself.files.count;

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

{

staticNSString *CellIdentifier = @"Cell";

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

// Configure the cell...

NSString *filePath = self.files[indexPath.row];

if ([[filePath pathExtension] isEqualToString:@"jpg"]) {

cell.textLabel.text = [filePath lastPathComponent];

cell.imageView.image = [UIImageimageWithContentsOfFile:filePath];

}elseif([[filePath pathExtension] isEqualToString:@"txt"]){

cell.textLabel.text = [filePath lastPathComponent];

}else{ //目录

cell.textLabel.text = [filePath lastPathComponent];

[cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];

}

return cell;

}

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{

NSString *filePath = self.files[indexPath.row];

if ([[filePath pathExtension] isEqualToString:@"jpg"]) {

[selfperformSegueWithIdentifier:@"pictureVC"sender:filePath];

}elseif([[filePath pathExtension] isEqualToString:@"txt"]){

[selfperformSegueWithIdentifier:@"txtVC"sender:filePath];

}else{ //目录

MXDocumentsViewController *docvc = [self.storyboardinstantiateViewControllerWithIdentifier:@"fileListTV"];

docvc.path = filePath;

[self.navigationControllerpushViewController:docvc animated:YES];

}

}

#pragma mark - Navigation

// In a story board-based application, you will often want to do a little preparation before navigation

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

{

if ([segue.identifierisEqualToString:@"pictureVC"]) {

MXPictureViewController *picvc = segue.destinationViewController;

picvc.path = sender;

}elseif ([segue.identifierisEqualToString:@"txtVC"]){

MXTxtViewController *txtvc = segue.destinationViewController;

txtvc.path = sender;

}

}