Java da Fayllar bilan Ishlash

1. Files Синфи

Fayllar bilan ishlash uchun, java.nio.file.Files deb atalmish yaxshi bir sinf bor. U hayotning barcha holatlariga mos keluvchi metodlarga ega. Ushbu sinfning barcha metodlari statik va Path turidagi obyektlar bilan ishlaydi. Metodlar juda ko'p, shuning uchun faqat asosiylarini ko'rib chiqamiz:

Path createFile(Path path)

Path createDirectory(Path path)

Path createDirectories(Path path)

Path createTempFile(prefix, suffix)

Path createTempDirectory(prefix)

void delete(Path path)

Path copy(Path src, Path dest)

Path move(Path src, Path dest)

boolean isDirectory(Path path)

boolean isRegularFile(Path path)

boolean exists(Path path)

long size(Path path)

byte[] readAllBytes(Path path)

String readString(Path path)

List<String> readAllLines(Path path)

Path write(Path path, byte[])

Path writeString(Path path, String str)

DirectoryStream<Path> newDirectoryStream(Path dir)

2. Fayllar va kataloglar yaratish

Fayllar va kataloglarni yaratish juda oson. Misollarda ko'rib chiqamiz:

Files.createFile(Path.of("c:\\readme.txt"));

Files.createDirectory(Path.of("c:\\test"));

Files.createDirectories(Path.of("c:\\test\\1\\2\\3"));

3. Nusxalash, ko'chirish va o'chirish

Fayllarni nusxalash, ko'chirish va o'chirish ham oson. Kataloglarga nisbatan, ular bo'sh bo'lishi kerak.

Path path1 = Path.of("c:\\readme.txt");
Path path2 = Path.of("c:\\readme-copy.txt");
Files.copy(path1, path2);

Path path1 = Path.of("c:\\readme.txt");
Path path2 = Path.of("d:\\readme-new.txt");
Files.move(path1, path2);

Path path = Path.of("d:\\readme-new.txt");
Files.delete(path);

4. Fayl turini va mavjudligini tekshirish

Borganingizda tashqaridan olingan bir yo'l bor bo'lsa, bu fayl yoki katalog ekanligini bilishni xohlaysiz. Umuman olganda, bu fayl/katalog mavjudmi yoxud yo'qmi?

Buning uchun maxsus metodlar bor. Shuningdek, fayl uzunligini ham osonlik bilan tekshirish mumkin:

Files.isRegularFile(Path.of("c:\\readme.txt"));

true

Files.isDirectory(Path.of("c:\\test"));

true

 Files.exists(Path.of("c:\\test\\1\\2\\3"));

false

Files.size(Path.of("c:\\readme.txt"));

10112

5. Faylning mazmuni bilan ishlash

Va nihoyat, faylning mazmunini oson o'qish yoki yozish uchun bir qator metodlar mavjud. Misol:

Path path = Path.of("c:\\readme.txt");
List<String> list = Files.readAllLines(path);

for (String str : list)
   System.out.println(str);

6. Katalog mazmunini olish

Hozir eng qiziqarli metodni ko'rib chiqamiz — berilgan katalogdagi fayllar va ichki kataloglarni olish.

Buning uchun maxsus metod mavjud — newDirectoryStream(), bu maxsus turdagi obyektni DirectoryStream<Path> qaytaradi. Unda iterator bor (!), va ushbu iterator yordamida berilgan katalogdagi barcha fayllar va ichki kataloglarni olish mumkin.

Bu osonroq ko'rinadi:

Path path = Path.of("c:\\windows");

try (DirectoryStream<Path> files = Files.newDirectoryStream(path)) {
   for (Path path : files)
      System.out.println(path);
}

Obyekt DirectoryStream<Path> ikki xususiyatga ega. Birinchidan, unda fayllar yo'llarini qaytaruvchi iterator bor va biz ushbu obyektni for-each siklida ishlatishimiz mumkin.

Ikkinchidan, ushbu obyekt ma'lumotlar oqimi hisoblanadi va uni close() metodi yordamida yopish yoki try-with-resources ichida ishlatish kerak.

7. Files.newInputStream Методи

Java 5 dan boshlab FileInputStream va FileOutputStream sinflari eskirgan deb hisoblana boshlandi. Ushbu sinflar obyektlar yaratilganda diskda darhol fayl yaratishi ularga salbiy ta'sir ko'rsatgan edi. Va barcha fayl yaratish bilan bog'liq xatolar chiqarilishi mumkin edi.

Kelib chiqqan natijada, bu unchalik yaxshi qaror emas deb topildi. Shuning uchun fayl obyektlarini yaratish uchun utilitar sinf metodlardan foydalanish tavsiya etiladi – java.nio.Files.

Eski fayl yaratish yondashuvi va yangisini taqqoslanishi:

String src = "c:\\projects\\log.txt";
InputStream input = new FileInputStream( src );

String src = "c:\\projects\\log.txt";
InputStream input = Files.newInputStream( Path.of( src ) );

Aynan shunday o'zgarish FileOutputStream uchun ham mavjud:

String src = "c:\\projects\\log.txt";
OutputStream  output = new FileOutputStream( src );

String src = "c:\\projects\\log.txt";
OutputStream  output = Files.newOutputStream( Path.of( src ) );