Comment lire les données de la ligne NSFileHandle par ligne?
https://stackoverflow.com/questions/3707427
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02-10-2019 - |
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J'ai un fichier texte contenant des données comme indiqué
par exemple.
PUFGUjVRallYZDNaazFtVjVObU1zWm5ZcUJUYU5ORk4zbGthNHNDVUdSMlFVQmpSVEoxUUNSallYaFhkanBITXBGR1NTQnpZRTltZE1OalVzSkdXQ0Z6WXR0V2RpTmpTdXgwTWs5V1lZSkZiWjFXT29OV2JSVlhaSTUwYUpwR040UUZXTzVHVXFoWFVRcFdWNHdVTUJ0Q1VHSmxXVlJVTlJCMVE1VTFWV
PUFGUjVRallYZDNaazFtVjVObU1zWm5ZcUJUYU5ORk4zbGthNHNDVUdSMlFVQmpSVEoxUUNSallYaFhkanBITXBGR1NTQnpZRTltZE1OalVzSkdXQ0Z6WXR0V2RpTmpTdXgwTWs5V1lZSkZiWjFXT29OV2JSVlhaSTUwYUpwR040UUZXTzVHVXFoWFVRcFdWNHdVTUJ0Q1VHSmxXVlJVTlJCMVE1VTFWV
Maintenant, je veux lire la ligne de données en ligne. Cela signifie d'abord que je veux lire
PUFGUjVRallYZDNaazFtVjVObU1zWm5ZcUJUYU5ORk4zbGthNHNDVUdSMlFVQmpSVEoxUUNSallYaFhkanBITXBGR1NTQnpZRTltZE1OalVzSkdXQ0Z6WXR0V2RpTmpTdXgwTWs5V1lZSkZiWjFXT29OV2JSVlhaSTUwYUpwR040UUZXTzVHVXFoWFVRcFdWNHdVTUJ0Q1VHSmxXVlJVTlJCMVE1VTFWV
et puis à côté restant. quelqu'un a une idée ??
La solution
Si votre fichier est petit, alors @ méthode de mipadi sera probablement très bien. Toutefois, si votre fichier est volumineux (> 1 Mo, peut-être?), Alors vous pouvez envisager de lire la ligne par ligne fichier. J'ai écrit une classe une fois pour le faire, que je vais coller ici:
//DDFileReader.h
@interface DDFileReader : NSObject {
NSString * filePath;
NSFileHandle * fileHandle;
unsigned long long currentOffset;
unsigned long long totalFileLength;
NSString * lineDelimiter;
NSUInteger chunkSize;
}
@property (nonatomic, copy) NSString * lineDelimiter;
@property (nonatomic) NSUInteger chunkSize;
- (id) initWithFilePath:(NSString *)aPath;
- (NSString *) readLine;
- (NSString *) readTrimmedLine;
#if NS_BLOCKS_AVAILABLE
- (void) enumerateLinesUsingBlock:(void(^)(NSString*, BOOL *))block;
#endif
@end
//DDFileReader.m
#import "DDFileReader.h"
@interface NSData (DDAdditions)
- (NSRange) rangeOfData_dd:(NSData *)dataToFind;
@end
@implementation NSData (DDAdditions)
- (NSRange) rangeOfData_dd:(NSData *)dataToFind {
const void * bytes = [self bytes];
NSUInteger length = [self length];
const void * searchBytes = [dataToFind bytes];
NSUInteger searchLength = [dataToFind length];
NSUInteger searchIndex = 0;
NSRange foundRange = {NSNotFound, searchLength};
for (NSUInteger index = 0; index < length; index++) {
if (((char *)bytes)[index] == ((char *)searchBytes)[searchIndex]) {
//the current character matches
if (foundRange.location == NSNotFound) {
foundRange.location = index;
}
searchIndex++;
if (searchIndex >= searchLength) { return foundRange; }
} else {
searchIndex = 0;
foundRange.location = NSNotFound;
}
}
return foundRange;
}
@end
@implementation DDFileReader
@synthesize lineDelimiter, chunkSize;
- (id) initWithFilePath:(NSString *)aPath {
if (self = [super init]) {
fileHandle = [NSFileHandle fileHandleForReadingAtPath:aPath];
if (fileHandle == nil) {
[self release]; return nil;
}
lineDelimiter = [[NSString alloc] initWithString:@"\n"];
[fileHandle retain];
filePath = [aPath retain];
currentOffset = 0ULL;
chunkSize = 10;
[fileHandle seekToEndOfFile];
totalFileLength = [fileHandle offsetInFile];
//we don't need to seek back, since readLine will do that.
}
return self;
}
- (void) dealloc {
[fileHandle closeFile];
[fileHandle release], fileHandle = nil;
[filePath release], filePath = nil;
[lineDelimiter release], lineDelimiter = nil;
currentOffset = 0ULL;
[super dealloc];
}
- (NSString *) readLine {
if (currentOffset >= totalFileLength) { return nil; }
NSData * newLineData = [lineDelimiter dataUsingEncoding:NSUTF8StringEncoding];
[fileHandle seekToFileOffset:currentOffset];
NSMutableData * currentData = [[NSMutableData alloc] init];
BOOL shouldReadMore = YES;
NSAutoreleasePool * readPool = [[NSAutoreleasePool alloc] init];
while (shouldReadMore) {
if (currentOffset >= totalFileLength) { break; }
NSData * chunk = [fileHandle readDataOfLength:chunkSize];
NSRange newLineRange = [chunk rangeOfData_dd:newLineData];
if (newLineRange.location != NSNotFound) {
//include the length so we can include the delimiter in the string
chunk = [chunk subdataWithRange:NSMakeRange(0, newLineRange.location+[newLineData length])];
shouldReadMore = NO;
}
[currentData appendData:chunk];
currentOffset += [chunk length];
}
[readPool release];
NSString * line = [[NSString alloc] initWithData:currentData encoding:NSUTF8StringEncoding];
[currentData release];
return [line autorelease];
}
- (NSString *) readTrimmedLine {
return [[self readLine] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
}
#if NS_BLOCKS_AVAILABLE
- (void) enumerateLinesUsingBlock:(void(^)(NSString*, BOOL*))block {
NSString * line = nil;
BOOL stop = NO;
while (stop == NO && (line = [self readLine])) {
block(line, &stop);
}
}
#endif
@end
Ensuite utiliser, vous feriez:
DDFileReader * reader = [[DDFileReader alloc] initWithFilePath:pathToMyFile];
NSString * line = nil;
while ((line = [reader readLine])) {
NSLog(@"read line: %@", line);
}
[reader release];
Ou (pour 10.6+ et iOS 4 +):
DDFileReader * reader = [[DDFileReader alloc] initWithFilePath:pathToMyFile];
[reader enumerateLinesUsingBlock:^(NSString * line, BOOL * stop) {
NSLog(@"read line: %@", line);
}];
[reader release];
Joyeux Noël. :)
Autres conseils
Je récrit ce pour être conforme ARC:
//
// DDFileReader.m
// PBX2OPML
//
// Created by michael isbell on 11/6/11.
// Copyright (c) 2011 BlueSwitch. All rights reserved.
//
//DDFileReader.m
#import "DDFileReader.h"
@interface NSData (DDAdditions)
- (NSRange) rangeOfData_dd:(NSData *)dataToFind;
@end
@implementation NSData (DDAdditions)
- (NSRange) rangeOfData_dd:(NSData *)dataToFind {
const void * bytes = [self bytes];
NSUInteger length = [self length];
const void * searchBytes = [dataToFind bytes];
NSUInteger searchLength = [dataToFind length];
NSUInteger searchIndex = 0;
NSRange foundRange = {NSNotFound, searchLength};
for (NSUInteger index = 0; index < length; index++) {
if (((char *)bytes)[index] == ((char *)searchBytes)[searchIndex]) {
//the current character matches
if (foundRange.location == NSNotFound) {
foundRange.location = index;
}
searchIndex++;
if (searchIndex >= searchLength) { return foundRange; }
} else {
searchIndex = 0;
foundRange.location = NSNotFound;
}
}
return foundRange;
}
@end
@implementation DDFileReader
@synthesize lineDelimiter, chunkSize;
- (id) initWithFilePath:(NSString *)aPath {
if (self = [super init]) {
fileHandle = [NSFileHandle fileHandleForReadingAtPath:aPath];
if (fileHandle == nil) {
return nil;
}
lineDelimiter = @"\n";
currentOffset = 0ULL; // ???
chunkSize = 10;
[fileHandle seekToEndOfFile];
totalFileLength = [fileHandle offsetInFile];
//we don't need to seek back, since readLine will do that.
}
return self;
}
- (void) dealloc {
[fileHandle closeFile];
currentOffset = 0ULL;
}
- (NSString *) readLine {
if (currentOffset >= totalFileLength) { return nil; }
NSData * newLineData = [lineDelimiter dataUsingEncoding:NSUTF8StringEncoding];
[fileHandle seekToFileOffset:currentOffset];
NSMutableData * currentData = [[NSMutableData alloc] init];
BOOL shouldReadMore = YES;
@autoreleasepool {
while (shouldReadMore) {
if (currentOffset >= totalFileLength) { break; }
NSData * chunk = [fileHandle readDataOfLength:chunkSize];
NSRange newLineRange = [chunk rangeOfData_dd:newLineData];
if (newLineRange.location != NSNotFound) {
//include the length so we can include the delimiter in the string
chunk = [chunk subdataWithRange:NSMakeRange(0, newLineRange.location+[newLineData length])];
shouldReadMore = NO;
}
[currentData appendData:chunk];
currentOffset += [chunk length];
}
}
NSString * line = [[NSString alloc] initWithData:currentData encoding:NSUTF8StringEncoding];
return line;
}
- (NSString *) readTrimmedLine {
return [[self readLine] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
}
#if NS_BLOCKS_AVAILABLE
- (void) enumerateLinesUsingBlock:(void(^)(NSString*, BOOL*))block {
NSString * line = nil;
BOOL stop = NO;
while (stop == NO && (line = [self readLine])) {
block(line, &stop);
}
}
#endif
@end
J'ai commencé un projet GitHub basé sur le code source de Dave DeLong . Nous vous invitons à améliorer le code. Maintenant, je peux lire les fichiers avant et en arrière.
NSString *fh = [NSString stringWithContentsOfFile:filePath encoding:fileEncoding error:NULL];
for (NSString *line in [fh componentsSeparatedByString:@"\n"]) {
// Do something with the line
}
Il n'y a pas d'API Cocoa, ou intégré dans des constructions de langage, pour lire un fichier ligne par ligne.
La réponse à cette question pour GRANDE Les fichiers texte ne nécessite pas une fonction personnalisée. Objective-C est un surensemble de c, et a donc les méthodes c pour faire exactement cela.
FILE* file = fopen("path to my file", "r");
size_t length;
char *cLine = fgetln(file,&length);
while (length>0) {
char str[length+1];
strncpy(str, cLine, length);
str[length] = '\0';
NSString *line = [NSString stringWithFormat:@"%s",str];
% Do what you want here.
cLine = fgetln(file,&length);
}
Notez que fgetln ne gardera pas votre retour à la ligne. De plus, nous +1 la longueur de la str parce que nous voulons faire de la place pour la terminaison NULL.
Voici une méthode que j'ai utilisé pour la lecture d'une ligne individuelle d'un nsInputStream. Notez qu'il est optimisé pour une meilleure lisibilité et non pour la vitesse. ; -)
- (NSString*) readLine: (NSInputStream*) inputStream {
NSMutableData* data = [NSMutableData data];
uint8_t oneByte;
do {
int actuallyRead = [inputStream read: &oneByte maxLength: 1];
if (actuallyRead == 1) {
[data appendBytes: &oneByte length: 1];
}
} while (oneByte != '\n');
return [[NSString alloc] initWithData: data encoding: NSUTF8StringEncoding];
Je trouve que GitX utilise un lecteur de ligne aussi bien.
Commander de dépôt de brotherbard sur GitHub ou site web de Michael Stapelberg .
Yang @ Joe
Agréable! Je vais regarder de plus près les prochains jours.
Je serais heureux si vous voulez fourchette mon dépôt sur GitHub et envoyez-moi une demande de traction .
J'ai modifié le FileReader à une catégorie NSFileHandle, espérons que cela pourrait aider les autres
@interface NSFileHandle (Readline)
- (NSString*)readLine;
- (NSString*)readLineBackwards;
@end
#import "NSFileHandle+Readline.h"
#import "NSDataExtensions.h"
@implementation NSFileHandle (Readline)
- (NSString*)readLine {
NSString * _lineDelimiter = @"\n";
NSData* newLineData = [_lineDelimiter dataUsingEncoding:NSUTF8StringEncoding];
NSMutableData* currentData = [[NSMutableData alloc] init];
BOOL shouldReadMore = YES;
NSUInteger _chunkSize = 10;
while (shouldReadMore) {
NSData* chunk = [self readDataOfLength:_chunkSize]; // always length = 10
if ([chunk length] == 0) {
break;
}
// Find the location and length of the next line delimiter.
NSRange newLineRange = [chunk rangeOfData:newLineData];
if (newLineRange.location != NSNotFound) {
// Include the length so we can include the delimiter in the string.
NSRange subDataRange = NSMakeRange(0, newLineRange.location + [newLineData length]);
unsigned long long newOffset = [self offsetInFile] - [chunk length] + newLineRange.location + [newLineData length];
[self seekToFileOffset:newOffset];
chunk = [chunk subdataWithRange:subDataRange];
shouldReadMore = NO;
}
[currentData appendData:chunk];
}
NSString* line = [currentData stringValueWithEncoding:NSASCIIStringEncoding];
return line;
}
- (NSString*)readLineBackwards {
NSString * _lineDelimiter = @"\n";
NSData* newLineData = [_lineDelimiter dataUsingEncoding:NSUTF8StringEncoding];
NSUInteger _chunkSize = 10;
NSMutableData* currentData = [[NSMutableData alloc] init];
BOOL shouldReadMore = YES;
while (shouldReadMore) {
unsigned long long offset;
NSUInteger currentChunkSize = _chunkSize;
if ([self offsetInFile] <= _chunkSize) {
offset = 0;
currentChunkSize = [self offsetInFile];
shouldReadMore = NO;
} else {
offset = [self offsetInFile] - _chunkSize;
}
NSLog(@"seek to offset %qu, offset in file is %qu", offset, [self offsetInFile]);
[self seekToFileOffset:offset];
NSData* chunk = [self readDataOfLength:currentChunkSize];
NSRange newLineRange = [chunk rangeOfDataBackwardsSearch:newLineData];
if (newLineRange.location == NSNotFound) {
[self seekToFileOffset:offset];
}
if (newLineRange.location != NSNotFound) {
NSUInteger subDataLoc = newLineRange.location;
NSUInteger subDataLen = currentChunkSize - subDataLoc;
chunk = [chunk subdataWithRange:NSMakeRange(subDataLoc, subDataLen)];
NSLog(@"got chunk data %@", [chunk stringValueWithEncoding:NSASCIIStringEncoding]);
shouldReadMore = NO;
[self seekToFileOffset:offset + newLineRange.location];
}
[currentData prepend:chunk];
}
NSString* line = [[NSString alloc] initWithData:currentData encoding:NSASCIIStringEncoding];
return [line autorelease];
}
@end
//
// NSDataExtensions.m
// LineReader
//
// Created by Tobias Preuss on 08.10.10.
// Copyright 2010 Tobias Preuss. All rights reserved.
//
#import "NSDataExtensions.h"
// -----------------------------------------------------------------------------
// NSData additions.
// -----------------------------------------------------------------------------
/**
Extension of the NSData class.
Data can be found forwards or backwards. Further the extension supplies a function
to convert the contents to string for debugging purposes.
@param Additions Category labeled Additions.
@returns An initialized NSData object or nil if the object could not be created.
*/
@implementation NSData (Additions)
/**
Returns a range of data.
@param dataToFind Data object specifying the delimiter and encoding.
@returns A range.
*/
- (NSRange)rangeOfData:(NSData*)dataToFind {
const void* bytes = [self bytes];
NSUInteger length = [self length];
const void* searchBytes = [dataToFind bytes];
NSUInteger searchLength = [dataToFind length];
NSUInteger searchIndex = 0;
NSRange foundRange = {NSNotFound, searchLength};
for (NSUInteger index = 0; index < length; index++) {
// The current character matches.
if (((char*)bytes)[index] == ((char*)searchBytes)[searchIndex]) {
// Store found location if not done earlier.
if (foundRange.location == NSNotFound) {
foundRange.location = index;
}
// Increment search character index to check for match.
searchIndex++;
// All search character match.
// Break search routine and return found position.
if (searchIndex >= searchLength) {
return foundRange;
}
}
// Match does not continue.
// Return to the first search character.
// Discard former found location.
else {
searchIndex = 0;
foundRange.location = NSNotFound;
}
}
return foundRange;
}
- (NSRange)rangeOfDataBackwardsSearch:(NSData*)dataToFind {
const void* bytes = [self bytes];
NSUInteger length = [self length];
const void* searchBytes = [dataToFind bytes];
NSUInteger searchLength = [dataToFind length];
NSUInteger searchIndex = 0;
NSRange foundRange = {NSNotFound, searchLength};
if (length < searchLength) {
return foundRange;
}
for (NSUInteger index = length - searchLength; index >= 0;) {
// NSLog(@"%c == %c", ((char*)bytes)[index], ((char*)searchBytes)[searchIndex]); /* DEBUG LOG */
if (((char*)bytes)[index] == ((char*)searchBytes)[searchIndex]) {
// The current character matches.
if (foundRange.location == NSNotFound) {
foundRange.location = index;
}
index++;
searchIndex++;
if (searchIndex >= searchLength) {
return foundRange;
}
}
else {
// Decrement to search backwards.
if (foundRange.location == NSNotFound) {
// Skip if first byte has been reached.
if (index == 0) {
foundRange.location = NSNotFound;
return foundRange;
}
index--;
}
// Jump over the former found location
// to avoid endless loop.
else {
index = index - 2;
}
searchIndex = 0;
foundRange.location = NSNotFound;
}
}
return foundRange;
}
- (NSString*)stringValueWithEncoding:(NSStringEncoding)encoding {
return [[NSString alloc] initWithData:self encoding:encoding];
}
@end
// -----------------------------------------------------------------------------
// NSMutableData additions.
// -----------------------------------------------------------------------------
/**
Extension of the NSMutableData class.
Data can be prepended in addition to the append function of the framework.
@param Additions Category labeled Additions.
@returns An initialized NSMutableData object or nil if the object could not be created.
*/
@implementation NSMutableData (Additions)
/**
Inserts the data before the data of the object.
@param data Data to be prepended.
*/
- (void)prepend:(NSData*)data {
NSMutableData* concat = [NSMutableData dataWithData:data];
[concat appendData:self];
[self setData:concat];
}
@end
Vous pouvez également consulter la bibliothèque CGIStream j'ai créé pour mon projet de serveur HTTP à https: //github.com/xcvista/ohttpd2/tree/master/CGIStream . Au lieu de descripteurs de fichiers, ce code fonctionne sur nsInputStream. Il est essentiellement un clone Objective-C de System.IO.StreamReader et System.IO.StreamWriter NET Framework de Microsoft.
Il fonctionnera avec non seulement des fichiers mais aussi des connecteurs réseau. Je l'utilise pour gérer le protocole HTTP, qui est le même nom du préfixe CGI.
Je cours dans la même situation avec d'autres circonstances, et voici ma solution à Swift 3. En supposant fichier texte à UTF8.
extension FileHandle {
func enumerateLines(_ block: @escaping (String, UnsafeMutablePointer<Bool>) -> Void) {
// find the end of file
var offset = self.offsetInFile
let eof = self.seekToEndOfFile()
self.seek(toFileOffset: offset)
let blockSize = 1024
var buffer = Data()
// process to the end of file
while offset + UInt64(buffer.count) < eof {
var found = false
// make sure buffer contains at least one CR, LF or null
while !found && offset + UInt64(buffer.count) < eof {
let block = self.readData(ofLength: blockSize)
buffer.append(block)
for byte in block {
if [0x0d, 0x0a, 0x00].contains(byte) {
found = true ; break
}
}
}
// retrieve lines within the buffer
var index = 0
var head = 0 // head of line
var done = false
buffer.enumerateBytes({ (pointer, count, stop) in
while index < count {
// find a line terminator
if [0x0d, 0x0a, 0x00].contains(pointer[index]) {
let lineData = Data(pointer[head ..< index])
if let line = String(bytes: lineData, encoding: .utf8) {
block(line, &stop) // stop requested
if pointer[index] == 0x0d && index+1 < count && pointer[index+1] == 0x0a {
index += 2 ; head = index
}
else { index += 1 ; head = index }
if stop { done = true ; return } // end of enumerateLines
}
else { return } // end of enumerateLines
}
else { index += 1 }
}
})
offset += UInt64(head)
buffer.replaceSubrange(0 ..< head, with: Data())
if done { // stop requested
self.seek(toFileOffset: offset)
return
}
}
}
Voici l'utilisation:
let fileURL = Bundle.main.url(forResource: "huge_file", withExtension: "txt")!
let fileHandle = try! FileHandle(forReadingFrom: fileURL)
fileHandle.enumerateLines { (line, stop) in
if someCondition { stop.pointee = true }
print(line)
}
/* let remaining = fileHandle.readDataToEndOfFile() */
https://gist.github.com/codelynx/c1de603a85e7503fe9597d027e93f4de
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