Java : FileVisitor con ejemplos

FileVisitor (Java SE 22 & JDK 22) en Java con ejemplos.
Encontrará muestras de código para la mayoría de los métodos FileVisitor<T>.

Nota :

Este artículo puede utilizar software de traducción para su comodidad. Consulte también la versión original en inglés.

Summary

Un visitante de archivos. Se proporciona una implementación de esta interfaz para los métodos Files.walkFileTree para visitar cada archivo en un árbol de archivos. (Traducción automática)

Class diagram

// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//└─target-dir
//    ├─dir1
//    │      aaa.txt
//    │      bbb.txt
//    │
//    └─dir2
//            ccc.txt
//            ddd.txt

// An example to delete a target directory with contents.
final FileVisitor<Path> visitor = new SimpleFileVisitor<>() {
    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
        System.out.println("visitFile          : " + file);

        Files.delete(file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
        System.out.println("postVisitDirectory : " + dir);

        if (exc != null) {
            throw exc;
        }

        Files.delete(dir);
        return FileVisitResult.CONTINUE;
    }
};

final var targetDir = Path.of("R:", "java-work", "target-dir");
System.out.println("target dir : " + targetDir);
System.out.println("exists : " + Files.exists(targetDir));

System.out.println("-- walkFileTree : start --");
Files.walkFileTree(targetDir, visitor);

System.out.println("-- walkFileTree : end --");
System.out.println("exists : " + Files.exists(targetDir));

// Result
// ↓
//target dir : R:\java-work\target-dir
//exists : true
//-- walkFileTree : start --
//visitFile          : R:\java-work\target-dir\dir1\aaa.txt
//visitFile          : R:\java-work\target-dir\dir1\bbb.txt
//postVisitDirectory : R:\java-work\target-dir\dir1
//visitFile          : R:\java-work\target-dir\dir2\ccc.txt
//visitFile          : R:\java-work\target-dir\dir2\ddd.txt
//postVisitDirectory : R:\java-work\target-dir\dir2
//postVisitDirectory : R:\java-work\target-dir
//-- walkFileTree : end --
//exists : false

Methods

FileVisitResult postVisitDirectory (T dir, IOException exc)

Se invoca para un directorio después de que se hayan visitado las entradas del directorio y todos sus descendientes. (Traducción automática)

// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//│  aaa.txt
//│  bbb.txt
//│
//├─dir1
//│  │  ccc.txt
//│  │  ddd.txt
//│  │
//│  └─dir1-2
//│          eee.txt
//│          fff.txt
//│
//└─dir2
//        ggg.txt
//        hhh.txt

final var start = Path.of("R:", "java-work");
System.out.println("start dir : " + start);

final var visitor = new FileVisitor<Path>() {
    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
        System.out.println("preVisitDirectory  : " + dir);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
        System.out.println("visitFile          : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFileFailed(Path file, IOException exc) {
        System.out.println("visitFileFailed    : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
        System.out.println("postVisitDirectory : " + dir);
        return FileVisitResult.CONTINUE;
    }
};

System.out.println("-- walkFileTree : start --");
Files.walkFileTree(start, visitor);

System.out.println("-- walkFileTree : end --");

// Result
// ↓
//start dir : R:\java-work
//-- walkFileTree : start --
//preVisitDirectory  : R:\java-work
//visitFile          : R:\java-work\aaa.txt
//visitFile          : R:\java-work\bbb.txt
//preVisitDirectory  : R:\java-work\dir1
//visitFile          : R:\java-work\dir1\ccc.txt
//visitFile          : R:\java-work\dir1\ddd.txt
//preVisitDirectory  : R:\java-work\dir1\dir1-2
//visitFile          : R:\java-work\dir1\dir1-2\eee.txt
//visitFile          : R:\java-work\dir1\dir1-2\fff.txt
//postVisitDirectory : R:\java-work\dir1\dir1-2
//postVisitDirectory : R:\java-work\dir1
//preVisitDirectory  : R:\java-work\dir2
//visitFile          : R:\java-work\dir2\ggg.txt
//visitFile          : R:\java-work\dir2\hhh.txt
//postVisitDirectory : R:\java-work\dir2
//postVisitDirectory : R:\java-work
//-- walkFileTree : end --

final var start = Path.of("R:", "java-work");
System.out.println("start dir : " + start);

final var visitor = new FileVisitor<Path>() {
    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
        System.out.println("preVisitDirectory  : " + dir);

        if (Path.of("dir1").equals(dir.getFileName())) {
            System.out.println("                     dir1 SKIP!");
            return FileVisitResult.SKIP_SUBTREE;
        }

        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
        System.out.println("visitFile          : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFileFailed(Path file, IOException exc) {
        System.out.println("visitFileFailed    : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
        System.out.println("postVisitDirectory : " + dir);
        return FileVisitResult.CONTINUE;
    }
};

System.out.println("-- walkFileTree : start --");
Files.walkFileTree(start, visitor);

System.out.println("-- walkFileTree : end --");

// Result
// ↓
//start dir : R:\java-work
//-- walkFileTree : start --
//preVisitDirectory  : R:\java-work
//visitFile          : R:\java-work\aaa.txt
//visitFile          : R:\java-work\bbb.txt
//preVisitDirectory  : R:\java-work\dir1
//                     dir1 SKIP!
//preVisitDirectory  : R:\java-work\dir2
//visitFile          : R:\java-work\dir2\ggg.txt
//visitFile          : R:\java-work\dir2\hhh.txt
//postVisitDirectory : R:\java-work\dir2
//postVisitDirectory : R:\java-work
//-- walkFileTree : end --

FileVisitResult preVisitDirectory (T dir, BasicFileAttributes attrs)

Se invoca para un directorio antes de que se visiten las entradas del directorio. (Traducción automática)

// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//│  aaa.txt
//│  bbb.txt
//│
//├─dir1
//│  │  ccc.txt
//│  │  ddd.txt
//│  │
//│  └─dir1-2
//│          eee.txt
//│          fff.txt
//│
//└─dir2
//        ggg.txt
//        hhh.txt

final var start = Path.of("R:", "java-work");
System.out.println("start dir : " + start);

final var visitor = new FileVisitor<Path>() {
    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
        System.out.println("preVisitDirectory  : " + dir);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
        System.out.println("visitFile          : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFileFailed(Path file, IOException exc) {
        System.out.println("visitFileFailed    : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
        System.out.println("postVisitDirectory : " + dir);
        return FileVisitResult.CONTINUE;
    }
};

System.out.println("-- walkFileTree : start --");
Files.walkFileTree(start, visitor);

System.out.println("-- walkFileTree : end --");

// Result
// ↓
//start dir : R:\java-work
//-- walkFileTree : start --
//preVisitDirectory  : R:\java-work
//visitFile          : R:\java-work\aaa.txt
//visitFile          : R:\java-work\bbb.txt
//preVisitDirectory  : R:\java-work\dir1
//visitFile          : R:\java-work\dir1\ccc.txt
//visitFile          : R:\java-work\dir1\ddd.txt
//preVisitDirectory  : R:\java-work\dir1\dir1-2
//visitFile          : R:\java-work\dir1\dir1-2\eee.txt
//visitFile          : R:\java-work\dir1\dir1-2\fff.txt
//postVisitDirectory : R:\java-work\dir1\dir1-2
//postVisitDirectory : R:\java-work\dir1
//preVisitDirectory  : R:\java-work\dir2
//visitFile          : R:\java-work\dir2\ggg.txt
//visitFile          : R:\java-work\dir2\hhh.txt
//postVisitDirectory : R:\java-work\dir2
//postVisitDirectory : R:\java-work
//-- walkFileTree : end --

final var start = Path.of("R:", "java-work");
System.out.println("start dir : " + start);

final var visitor = new FileVisitor<Path>() {
    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
        System.out.println("preVisitDirectory  : " + dir);

        if (Path.of("dir1").equals(dir.getFileName())) {
            System.out.println("                     dir1 SKIP!");
            return FileVisitResult.SKIP_SUBTREE;
        }

        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
        System.out.println("visitFile          : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFileFailed(Path file, IOException exc) {
        System.out.println("visitFileFailed    : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
        System.out.println("postVisitDirectory : " + dir);
        return FileVisitResult.CONTINUE;
    }
};

System.out.println("-- walkFileTree : start --");
Files.walkFileTree(start, visitor);

System.out.println("-- walkFileTree : end --");

// Result
// ↓
//start dir : R:\java-work
//-- walkFileTree : start --
//preVisitDirectory  : R:\java-work
//visitFile          : R:\java-work\aaa.txt
//visitFile          : R:\java-work\bbb.txt
//preVisitDirectory  : R:\java-work\dir1
//                     dir1 SKIP!
//preVisitDirectory  : R:\java-work\dir2
//visitFile          : R:\java-work\dir2\ggg.txt
//visitFile          : R:\java-work\dir2\hhh.txt
//postVisitDirectory : R:\java-work\dir2
//postVisitDirectory : R:\java-work
//-- walkFileTree : end --

FileVisitResult visitFile (T file, BasicFileAttributes attrs)

Se invoca para un archivo en un directorio. (Traducción automática)

// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//│  aaa.txt
//│  bbb.txt
//│
//├─dir1
//│  │  ccc.txt
//│  │  ddd.txt
//│  │
//│  └─dir1-2
//│          eee.txt
//│          fff.txt
//│
//└─dir2
//        ggg.txt
//        hhh.txt

final var start = Path.of("R:", "java-work");
System.out.println("start dir : " + start);

final var visitor = new FileVisitor<Path>() {
    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
        System.out.println("preVisitDirectory  : " + dir);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
        System.out.println("visitFile          : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFileFailed(Path file, IOException exc) {
        System.out.println("visitFileFailed    : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
        System.out.println("postVisitDirectory : " + dir);
        return FileVisitResult.CONTINUE;
    }
};

System.out.println("-- walkFileTree : start --");
Files.walkFileTree(start, visitor);

System.out.println("-- walkFileTree : end --");

// Result
// ↓
//start dir : R:\java-work
//-- walkFileTree : start --
//preVisitDirectory  : R:\java-work
//visitFile          : R:\java-work\aaa.txt
//visitFile          : R:\java-work\bbb.txt
//preVisitDirectory  : R:\java-work\dir1
//visitFile          : R:\java-work\dir1\ccc.txt
//visitFile          : R:\java-work\dir1\ddd.txt
//preVisitDirectory  : R:\java-work\dir1\dir1-2
//visitFile          : R:\java-work\dir1\dir1-2\eee.txt
//visitFile          : R:\java-work\dir1\dir1-2\fff.txt
//postVisitDirectory : R:\java-work\dir1\dir1-2
//postVisitDirectory : R:\java-work\dir1
//preVisitDirectory  : R:\java-work\dir2
//visitFile          : R:\java-work\dir2\ggg.txt
//visitFile          : R:\java-work\dir2\hhh.txt
//postVisitDirectory : R:\java-work\dir2
//postVisitDirectory : R:\java-work
//-- walkFileTree : end --

final var start = Path.of("R:", "java-work");
System.out.println("start dir : " + start);

final var visitor = new FileVisitor<Path>() {
    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
        System.out.println("preVisitDirectory  : " + dir);

        if (Path.of("dir1").equals(dir.getFileName())) {
            System.out.println("                     dir1 SKIP!");
            return FileVisitResult.SKIP_SUBTREE;
        }

        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
        System.out.println("visitFile          : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFileFailed(Path file, IOException exc) {
        System.out.println("visitFileFailed    : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
        System.out.println("postVisitDirectory : " + dir);
        return FileVisitResult.CONTINUE;
    }
};

System.out.println("-- walkFileTree : start --");
Files.walkFileTree(start, visitor);

System.out.println("-- walkFileTree : end --");

// Result
// ↓
//start dir : R:\java-work
//-- walkFileTree : start --
//preVisitDirectory  : R:\java-work
//visitFile          : R:\java-work\aaa.txt
//visitFile          : R:\java-work\bbb.txt
//preVisitDirectory  : R:\java-work\dir1
//                     dir1 SKIP!
//preVisitDirectory  : R:\java-work\dir2
//visitFile          : R:\java-work\dir2\ggg.txt
//visitFile          : R:\java-work\dir2\hhh.txt
//postVisitDirectory : R:\java-work\dir2
//postVisitDirectory : R:\java-work
//-- walkFileTree : end --

FileVisitResult visitFileFailed (T file, IOException exc)

Se invoca para un archivo que no se pudo visitar. (Traducción automática)

// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//├─dir1
//└─dir2
//        aaa.txt
//
//PS R:\java-work> ls | Get-Acl
//
//    Directory: R:\java-work
//
//Path Owner           Access
//---- -----           ------
//dir1 MY-PC\test-user BUILTIN\Administrators Deny  ReadData…
//dir2 MY-PC\test-user BUILTIN\Administrators Allow  FullControl…

// Intentionally deny read permission to the dir1 directory.

final var start = Path.of("R:", "java-work");
System.out.println("start dir : " + start);

final var visitor = new FileVisitor<Path>() {
    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
        System.out.println("preVisitDirectory  : " + dir);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
        System.out.println("visitFile          : " + file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFileFailed(Path file, IOException exc) {
        System.out.println("visitFileFailed    : " + file);
        System.out.println("IOException        : " + exc);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
        System.out.println("postVisitDirectory : " + dir);
        return FileVisitResult.CONTINUE;
    }
};

System.out.println("-- walkFileTree : start --");
Files.walkFileTree(start, visitor);

System.out.println("-- walkFileTree : end --");

// Result
// ↓
//start dir : R:\java-work
//-- walkFileTree : start --
//preVisitDirectory  : R:\java-work
//visitFileFailed    : R:\java-work\dir1
//IOException        : java.nio.file.AccessDeniedException: R:\java-work\dir1
//preVisitDirectory  : R:\java-work\dir2
//visitFile          : R:\java-work\dir2\aaa.txt
//postVisitDirectory : R:\java-work\dir2
//postVisitDirectory : R:\java-work
//-- walkFileTree : end --

Ejemplos de API
- File
- FileChannel
- FileLock
- Files
- FileStore (Storage)
- FileSystemException
- FileVisitor
  - SimpleFileVisitor
- Path
- StandardCopyOption

Java : FileVisitor con ejemplos

Summary

Methods

FileVisitResult postVisitDirectory (T dir, IOException exc)

FileVisitResult preVisitDirectory (T dir, BasicFileAttributes attrs)

FileVisitResult visitFile (T file, BasicFileAttributes attrs)

FileVisitResult visitFileFailed (T file, IOException exc)

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