把一个文件夹下文件分别归类

实用场景： 例如在一个文件目录下面文件很多，现在要把这么多的文件分别移动(剪切)到各自的小目录下面，可以定制每个文件目录下存放的文件数量。

代码如下：

package com.test.file;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * divide a heap of files into specified category
 * 
 * @author qgao
 */
public class FileUtils {
  public FileUtils() {

  }

  /**
   * classify a heap of files ,store them in some folders each folder have the
   * same number of files
   * 
   * @param pathname
   * @throws IOException
   */
  public void classifyFile(String pathname, int num, String prefix)
      throws IOException {
    if (num <= 0)
      return;
    File dir = new File(pathname);
    File[] files = dir.listFiles();
    int count = 0;
    int folder = 0;
    File tmpFolder = null;

    for (int i = 0; i < files.length; i++) {
      if (files[i].isFile()) {
        if (count % num == 0) {
          File temp =
              new File(pathname + File.separator + prefix
                  + String.valueOf(folder++));

          temp.mkdir();

          tmpFolder = temp;
        }
        this.cutFile(files[i], tmpFolder);
        count++;
      }
    }

  }

  public void classifyFile(String pathname, String prefix) throws IOException {
    this.classifyFile(pathname, 10, prefix);
  }

  public void classifyFile(String pathname) throws IOException {
    this.classifyFile(pathname, 10, "");
  }

  /**
   * cut a file from one folder to anther foler
   * 
   * @param file the source file
   * @param temp the target folder
   * @throws IOException
   */
  public void cutFile(File file, File folderPath) throws IOException {
    File srcFile = file;
    if (srcFile.isFile()) {
      File desFile =
          new File(folderPath.getAbsolutePath() + File.separator
              + srcFile.getName());
      FileInputStream input = new FileInputStream(srcFile);
      FileOutputStream output = new FileOutputStream(desFile);
      try {

        byte[] buffer = new byte[4096];
        int n = 0;
        while (-1 != (n = input.read(buffer))) {
          System.out.println(n);
          output.write(buffer, 0, n);
        }

      } finally {
        try {
          if (input != null) {
            input.close();
          }
          if (output != null) {
            output.close();
          }
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
      srcFile.delete();
    } else
      return;
  }
}