Java 8: Copy directory recursively?

问题:

I see that Java 8 has significantly cleaned up reading the contents of a file into a String:

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

I am wondering if there is something similar (cleaner/less code/more concise) for copying directories recursively. In Java 7 land, it's still something like:

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();     } } 

Any improvements here in Java 8?

回答1:

How about the following code

public  void copyFolder(File src, File dest) throws IOException{         try (Stream<Path> stream = Files.walk(src.toPath())) {             stream.forEach(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();                 }              });          }      } 

回答2:

This version uses Files.walk and Path parameters as Java 8 suggests.

    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(); } } 

回答3:

In this way the code looks a bit simpler

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);     } } 

回答4:

my 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();             }         }     } } 

回答5:

and one more version:

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; } 

its code use java8 Files.walkFileTree function.

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