java nio: walkFileTree实现文件夹复制移动删除

客官°小女子只卖身不卖艺 2022-07-13 14:53 466阅读 0赞

从java 1.7开始，java提供了java.noi.file.Files类用于更方便的实现文件/文件夹操作。  
在Files中提供了丰富的静态方法用于文件操作,Files也提供了文件移动和复制操作(`Files.move,Files.copy`)，但是对于不为的空文件夹,不能调用`Files.move,Files.copy`实现文件夹下所有文件的复制和移动。  
根据`Files.move,Files.copy`的说明，如果要移动/复制包含子目录的文件夹，需要用Files.walkFileTree方法配合`Files.move,Files.copy`来实现。以下是实现代码:

NioFileUtil.java

package net.gdface.iadb;
    
    import java.io.IOException;
    import java.nio.file.CopyOption;
    import java.nio.file.DirectoryNotEmptyException;
    import java.nio.file.FileVisitResult;
    import java.nio.file.Files;
    import java.nio.file.Path;
    import java.nio.file.SimpleFileVisitor;
    import java.nio.file.StandardCopyOption;
    import java.nio.file.attribute.BasicFileAttributes;
    
    /**
     * 使用于NIO实现文件夹的复制/移动,删除<br>
     * 需要java 1.7以上版本支持
     * @author guyadong
     *
     */
    public class NioFileUtil {
        
        /**
         * 复制文件夹
         * @param source
         * @param target
         * @param options
         * @throws IOException
         * @see {@link #operateDir(boolean, Path, Path, CopyOption...)}
         */
        public static void copyDir(Path source, Path target, CopyOption... options) throws IOException{
            operateDir(false, source, target, options);
        }
        /**
         * 移动文件夹
         * @param source
         * @param target
         * @param options
         * @throws IOException
         * @see {@link #operateDir(boolean, Path, Path, CopyOption...)}
         */
        public static void moveDir(Path source, Path target, CopyOption... options) throws IOException{
            operateDir(true, source, target, options);
        }
        /**
         * 复制/移动文件夹
         * @param move 操作标记，为true时移动文件夹,否则为复制
         * @param source 要复制/移动的源文件夹
         * @param target 源文件夹要复制/移动到的目标文件夹
         * @param options 文件复制选项 
         * @throws IOException
         * @see Files#move(Path, Path, CopyOption...)
         * @see Files#copy(Path, Path, CopyOption...)
         * @see Files#walkFileTree(Path, java.nio.file.FileVisitor)
         */
        public static void operateDir(boolean move,Path source, Path target, CopyOption... options) throws IOException{
            if(null==source||!Files.isDirectory(source))
                throw new IllegalArgumentException("source must be directory");
            Path dest = target.resolve(source.getFileName());
            // 如果相同则返回
            if(Files.exists(dest)&&Files.isSameFile(source, dest))return;
            // 目标文件夹不能是源文件夹的子文件夹
            // isSub方法实现参见另一篇博客 http://blog.csdn.net/10km/article/details/54425614
            if(isSub(source,dest))
                throw new IllegalArgumentException("dest must not  be sub directory of source");
            boolean clear=true;     
            for(CopyOption option:options)
                if(StandardCopyOption.REPLACE_EXISTING==option){
                    clear=false;
                    break;
                }
            // 如果指定了REPLACE_EXISTING选项则不清除目标文件夹
            if(clear)
                deleteIfExists(dest);
            Files.walkFileTree(source, 
                    new SimpleFileVisitor<Path>() {
    
                        @Override
                        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
                            // 在目标文件夹中创建dir对应的子文件夹
                            Path subDir = 0==dir.compareTo(source)?dest:dest.resolve(dir.subpath(source.getNameCount(), dir.getNameCount()));
                            Files.createDirectories(subDir);
                            return FileVisitResult.CONTINUE;
                        }
    
                        @Override
                        public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                            if(move)
                                Files.move(file, dest.resolve(file.subpath(source.getNameCount(), file.getNameCount())),options);
                            else
                                Files.copy(file, dest.resolve(file.subpath(source.getNameCount(), file.getNameCount())),options);
                            return FileVisitResult.CONTINUE;
                        }
    
                        @Override
                        public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
                            // 移动操作时删除源文件夹
                            if(move)
                                Files.delete(dir);
                            return super.postVisitDirectory(dir, exc);
                        }
                    });
        }
    
        /**
         * 强制删除文件/文件夹(含不为空的文件夹)<br>
         * @param dir
         * @throws IOException
         * @see Files#deleteIfExists(Path)
         * @see Files#walkFileTree(Path, java.nio.file.FileVisitor)
         */
        public static void deleteIfExists(Path dir) throws IOException {
            try {
                Files.deleteIfExists(dir);
            } catch (DirectoryNotEmptyException e) {
                Files.walkFileTree(dir, new SimpleFileVisitor<Path>() {
                    @Override
                    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                        Files.delete(file);
                        return FileVisitResult.CONTINUE;
                    }
    
                    @Override
                    public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
                        Files.delete(dir);
                        return super.postVisitDirectory(dir, exc);
                    }
                });
            }
        }
    
    }

测试代码

public void testCopy() throws IOException{
            Path start = Paths.get("d:\\tmp\\storeroot\\origin");
            Path target = Paths.get("E:\\tmp\\storeroot");
            NioFileUtil.copyDir(start, target);
        }

关于Files.walkFileTree方法的使用说明，参见这篇博客[《walkFileTree、FileVisitor（遍历文件/目录）》][walkFileTree_FileVisitor],说得很详细了

[walkFileTree_FileVisitor]: http://blog.csdn.net/lirx_tech/article/details/51424569