Java NIO.2 —— 文件或目录拷贝操作

import java.nio.file.FileSystemLoopException;
 import java.nio.file.attribute.FileTime;
 import java.io.IOException;
 import java.nio.file.FileVisitOption;
 import java.nio.file.FileVisitResult;
 import java.nio.file.FileVisitor;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.attribute.BasicFileAttributes;
 import java.util.EnumSet;
 import static java.nio.file.StandardCopyOption.REPLACE_EXISTING;
 import static java.nio.file.StandardCopyOption.COPY_ATTRIBUTES;
 
class CopyTree implements FileVisitor {
 
   private final Path copyFrom;
    private final Path copyTo;
 
   public CopyTree(Path copyFrom, Path copyTo) {
         this.copyFrom = copyFrom;
         this.copyTo = copyTo;
     }
 
   static void copySubTree(Path copyFrom, Path copyTo) throws IOException {
         try {
             Files.copy(copyFrom, copyTo, REPLACE_EXISTING, COPY_ATTRIBUTES);
         } catch (IOException e) {
             System.err.println("Unable to copy " + copyFrom + " [" + e + "]");
         }
 
    }
 
   @Override
    public FileVisitResult postVisitDirectory(Object dir, IOException exc) 
                                                                     throws IOException {
         if (exc == null) {
             Path newdir = copyTo.resolve(copyFrom.relativize((Path) dir));
             try {
                 FileTime time = Files.getLastModifiedTime((Path) dir);
                 Files.setLastModifiedTime(newdir, time);
             } catch (IOException e) {
                 System.err.println("Unable to copy all attributes to: " + newdir+" ["+e+ "]");
             }
         } else {
             throw exc;
         }
 
        return FileVisitResult.CONTINUE;
     }
 
    @Override
     public FileVisitResult preVisitDirectory(Object dir, BasicFileAttributes attrs) 
                                                                      throws IOException {
         System.out.println("Copy directory: " + (Path) dir);
         Path newdir = copyTo.resolve(copyFrom.relativize((Path) dir));
         try {
             Files.copy((Path) dir, newdir, REPLACE_EXISTING, COPY_ATTRIBUTES);
         } catch (IOException e) {
             System.err.println("Unable to create " + newdir + " [" + e + "]");
             return FileVisitResult.SKIP_SUBTREE;
         }
 
        return FileVisitResult.CONTINUE;
     }
 
    @Override
     public FileVisitResult visitFile(Object file, BasicFileAttributes attrs) 
                                                                      throws IOException {
         System.out.println("Copy file: " + (Path) file);
         copySubTree((Path) file, copyTo.resolve(copyFrom.relativize((Path) file)));
         return FileVisitResult.CONTINUE;
     }
 
    @Override
     public FileVisitResult visitFileFailed(Object file, IOException exc) 
                                                                     throws IOException {
         if (exc instanceof FileSystemLoopException) {
             System.err.println("Cycle was detected: " + (Path) file);
         } else {
             System.err.println("Error occurred, unable to copy:" +(Path) file+" ["+ exc + "]");
         }
 
        return FileVisitResult.CONTINUE;
     }
 }
 
class Main {
 
    public static void main(String[] args) throws IOException {
 
        Path copyFrom = Paths.get("C:/rafaelnadal");
         Path copyTo = Paths.get("C:/rafaelnadal_copy");
 
        CopyTree walk = new CopyTree(copyFrom, copyTo);
         EnumSet opts = EnumSet.of(FileVisitOption.FOLLOW_LINKS);
 
        Files.walkFileTree(copyFrom, opts, Integer.MAX_VALUE, walk);
     }
 }