Java SimpleFileVisitor遍历文件夹与File遍历文件夹的速度对比

来源：互联网发布：mac上玩dota2 编辑：程序博客网时间：2024/05/29 14:21

测试对比File类递归与SimpleFileVisitor类遍历文件夹的耗时：

package other;import java.io.File;import java.io.IOException;import java.nio.file.FileVisitResult;import java.nio.file.Files;import java.nio.file.Path;import java.nio.file.Paths;import java.nio.file.SimpleFileVisitor;import java.nio.file.attribute.BasicFileAttributes;import java.util.ArrayList;import java.util.Arrays;import java.util.List;public class FilterMp3 {private List<File> musicList = new ArrayList<>();private List<File> musicList2 = new ArrayList<>();private long fLen = 1024*1024*3;private String filterD = "D:/";//遍历方法1：public List<File> getLocalMp3(){File[] rootDirectory = new File(filterD).listFiles();long start = System.currentTimeMillis();System.out.println("开始递归" + start);nextDirectory(rootDirectory);long end = System.currentTimeMillis();System.out.println("结束递归"+ end);System.out.println("mp3集合长度："+musicList.size() + " 耗时：" + (end - start) + "ms");return musicList;}private void nextDirectory(File[] directory){//System.out.println("directory:"+ Arrays.toString(directory));for(File f : directory){//System.out.println(f.getName());if(f.isDirectory() && !f.isHidden() && !f.getName().startsWith(".")){File[] child = f.listFiles();nextDirectory(child);}else if(f.getName().endsWith(".mp3") && f.length()>fLen){musicList.add(f);}}}//遍历方法2：private List<File> getMp3FromeFileVisitor() throws IOException{long start2 = System.currentTimeMillis();Files.walkFileTree(Paths.get(filterD), new SimpleFileVisitor<Path>(){@Overridepublic FileVisitResult visitFile(Path file,BasicFileAttributes attrs){if(file.getFileName().toString().endsWith(".mp3") && attrs.size()>fLen){musicList2.add(file.toFile());//System.out.println("文件："+file.toFile().getName());}return FileVisitResult.CONTINUE;}@Overridepublic FileVisitResult preVisitDirectory(Path dir,BasicFileAttributes attrs){//System.out.println("方法2访问文件夹：" + dir);return FileVisitResult.CONTINUE;}@Overridepublic FileVisitResult visitFileFailed(Path file,IOException e){return FileVisitResult.CONTINUE;}});long end2 = System.currentTimeMillis();System.out.println("方法2结果：" + musicList2.size()+" " + "用时：" +(end2 - start2) +"ms");return musicList2;}public static void main(String[] args) {FilterMp3 fm = new FilterMp3();fm.getLocalMp3();try {fm.getMp3FromeFileVisitor();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}

运行结果：SimpleFileVisitor遍历比File遍历快将近50%

开始递归1513145408629
结束递归1513145416589
mp3集合长度：196 耗时：7960ms
方法2结果：196 用时：4157ms

使用SimpleFileVisitor时每次读到.dll文件时就会报错提示“System information……”，在visitFileFailed()中使用return FileVisiResult.CONTINUE之后正常。

之所以SimpleFileVisitor比File快，可能就是SimpleFileVisitor忽略了系统文件吧？

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