Question

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;

public class DirectoryContents {

    public static void main(String[] args) throws IOException {

        File f = new File("."); 
        FileFilter directoryFilter = new FileFilter() {
            public boolean accept(File file) {
            return file.isDirectory();
            }
        };

        File[] files = f.listFiles(directoryFilter);
        for (File file : files) {
            if (file.isDirectory())
                System.out.print("directory:"); 
            else
                System.out.print("     file:");

            System.out.println(file.getCanonicalPath());
        }
    }
}

我能够列出父目录中的所有子目录。但是我想在java.Is中搜索特定的子目录吗？

directory:C:\projects\workspace\testing

如何仅列出子目录（z1）而不是文件？（子目录z1存在于各种子目录中）

directory:C:\projects\workspace\testing\z1
directory:C:\projects\workspace\testing\f5\z1
directory:C:\projects\workspace\testing\f5\a\g\h\d

输出应该是包含z1

的目录

Answer 1

Java 7使这种类型的东西变得容易，具有很大的灵活性。我会使用带有glob模式的Java 7 PathMatcher（如果需要复杂性，则使用正则表达式模式）并在FileVistor中使用它。然后只需通过Files.walkFileTree()浏览文件树。

import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.PathMatcher;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;

public class StackOverflow20443793
{
    //Our FileVisitor Implementation. We extend SimpleFileVisitor to save work
    protected class Finder extends SimpleFileVisitor<Path>
    {
        private final PathMatcher matcher;

        Finder(String pattern)
        {
            matcher = FileSystems.getDefault().getPathMatcher("glob:" + pattern);
        }

        void find(Path path)
        {
            Path name = path.getFileName();
            if ((name != null) && matcher.matches(name))
            {
                processDirectory(path);
            }
        }


        @Override
        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException
        {
            //Since we only care about directories, we only override 
            // the preVisitDirectory method. The super does null checks for us
            super.preVisitDirectory(dir, attrs);
            find(dir);
            return FileVisitResult.CONTINUE;
        }
    }


    private void findAndProcessSubDirectories(Path startingDirectory, String pattern) throws IOException
    {
        Finder finder = new Finder(pattern);
        Files.walkFileTree(startingDirectory, finder);
    }

    private void processDirectory(Path dir)
    {
        System.out.println(dir);
    }

    public static void main(String... args) throws Exception
    {
        StackOverflow20443793 runner = new StackOverflow20443793();
        //Find all directories in path named "z1"
        runner.findAndProcessSubDirectories(Paths.get("P:\\tmp\\findExample"), "z1");
        System.out.println("=====");
        //Find all directories in path named "z*"
        runner.findAndProcessSubDirectories(Paths.get("P:\\tmp\\findExample"), "z*");

        System.exit(0);
    }
}

输出：

    C:\projects\workspace\testing\f5\a\g\h\d\z1
    C:\projects\workspace\testing\f5\z1
    C:\projects\workspace\testing\z1
    =====
    C:\projects\workspace\testing\f5\a\g\h\d\z1
    C:\projects\workspace\testing\f5\z1
    C:\projects\workspace\testing\z1
    C:\projects\workspace\testing\z2

有关更多信息和示例，请参阅http://docs.oracle.com/javase/tutorial/essential/io/find.html和我链接的JavaDoc。

Answer 2

两件事：

搜索子目录的最简单方法是递归。
您需要在打印前检查文件名。您可以使用".*z1.*

regular expressions

总之类似

private static final FileFilter directoryFilter = new FileFilter() {
  public boolean accept(File file) {
    return file.isDirectory();
  }
};

private static void printDirectories(File dir, string pattern) {
  // Print this directory if it matches the pattern
  if (dir.getName().matches(pattern)) {
    System.out.println(dir.getAbsolutePath());
  }
  // Search all sub directories
  for (String string : f.listFiles(directoryFilter)) {
    printDirectories(subDir);
  }
}

public static void main(String[] args) {
  printDirectories(new File("."), ".*z1.*");
}

允许通配符从父目录中搜索子目录？

2 个答案: