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; }}