recursion - con - Java 8: ¿Copiar directorio recursivamente?

copiar directorio java

Question

Veo que Java 8 ha limpiado significativamente la lectura del contenido de un archivo en una cadena:

String contents = new String(Files.readAllBytes(Paths.get(new URI(someUrl))));

Me pregunto si hay algo similar (más limpio / menos código / más conciso) para copiar directorios de forma recursiva. En la tierra de Java 7, sigue siendo algo como:

public void copyFolder(File src, File dest) throws IOException{
if(src.isDirectory()){
if(!dest.exists()){
dest.mkdir();
}
String files[] = src.list();
for (String file : files) {
File srcFile = new File(src, file);
File destFile = new File(dest, file);
copyFolder(srcFile,destFile);
}
} else {
InputStream in = new FileInputStream(src);
OutputStream out = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
while ((length = in.read(buffer)) > 0){
out.write(buffer, 0, length);
}
in.close();
out.close();
}
}

¿Alguna mejora aquí en Java 8?

Answer 1

¿Qué tal el siguiente código?

public void copyFolder(File src, File dest) throws IOException {
try (Stream<Path> stream = Files.walk(src.toPath())) {
stream.forEachOrdered(sourcePath -> {
try {
Files.copy(
/*Source Path*/
sourcePath,
/*Destination Path */
src.toPath().resolve(dest.toPath().relativize(sourcePath)));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
});
}
}

Answer 2

De esta manera el código se ve un poco más simple.

public void copyFolder(Path src, Path dest) throws IOException {
Files.walk(src)
.forEach(source -> copy(source, dest.resolve(src.relativize(source))));
}
private void copy(Path source, Path dest) {
try {
Files.copy(source, dest, REPLACE_EXISTING);
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
}

Answer 3

Esta versión usa los parámetros Files.walk y Path como sugiere Java 8.

public static void copyFolder(Path src, Path dest) {
try {
Files.walk( src ).forEach( s -> {
try {
Path d = dest.resolve( src.relativize(s) );
if( Files.isDirectory( s ) ) {
if( !Files.exists( d ) )
Files.createDirectory( d );
return;
}
Files.copy( s, d );// use flag to override existing
} catch( Exception e ) {
e.printStackTrace();
}
});
} catch( Exception ex ) {
ex.printStackTrace();
}
}

Answer 4

mi version:

static private void copyFolder(File src, File dest) {
// checks
if(src==null || dest==null)
return;
if(!src.isDirectory())
return;
if(dest.exists()){
if(!dest.isDirectory()){
//System.out.println("destination not a folder " + dest);
return;
}
} else {
dest.mkdir();
}
if(src.listFiles()==null || src.listFiles().length==0)
return;
for(File file: src.listFiles()){
File fileDest = new File(dest, file.getName());
//System.out.println(fileDest.getAbsolutePath());
if(file.isDirectory()){
copyFolder(file, fileDest);
}else{
if(fileDest.exists())
continue;
try {
Files.copy(file.toPath(), fileDest.toPath());
} catch (IOException e) {
//e.printStackTrace();
}
}
}
}

Answer 5

y una versión más:

static void copyFolder(File src, File dest){
// checks
if(src==null || dest==null)
return;
if(!src.isDirectory())
return;
if(dest.exists()){
if(!dest.isDirectory()){
//System.out.println("destination not a folder " + dest);
return;
}
} else {
dest.mkdir();
}
if(src.listFiles()==null || src.listFiles().length==0)
return;
String strAbsPathSrc = src.getAbsolutePath();
String strAbsPathDest = dest.getAbsolutePath();
try {
Files.walkFileTree(src.toPath(), new SimpleFileVisitor<Path>() {
@Override
public FileVisitResult visitFile(Path file,
BasicFileAttributes attrs) throws IOException {
File dstFile = new File(strAbsPathDest + file.toAbsolutePath().toString().substring(strAbsPathSrc.length()));
if(dstFile.exists())
return FileVisitResult.CONTINUE;
if(!dstFile.getParentFile().exists())
dstFile.getParentFile().mkdirs();
//System.out.println(file + " " + dstFile.getAbsolutePath());
Files.copy(file, dstFile.toPath());
return FileVisitResult.CONTINUE;
}
});
} catch (IOException e) {
//e.printStackTrace();
return;
}
return;
}

Su código usa la función java8 Files.walkFileTree.