private Optional<FileInfo> getNextFile() {7   /* Filter to exclude finished or hidden files */8   FileFilter filter = new FileFilter() {9     public boolean accept(File candidate) {
10       String fileName = candidate.getName();
11       if ((candidate.isDirectory()) ||
12           (fileName.endsWith(completedSuffix)) ||
13           (fileName.startsWith(".")) ||
14           ignorePattern.matcher(fileName).matches()) {
15         return false;
16       }
17       return true;
18     }
19   };
20   List<File> candidateFiles = Arrays.asList(spoolDirectory.listFiles(filter)); //获取spoolDirectory下满足条件的文件
21   if (candidateFiles.isEmpty()) {
22     return Optional.absent();
23   } else {
24     Collections.sort(candidateFiles, new Comparator<File>() { //按最后修改时间排序文件
25       public int compare(File a, File b) {
26         int timeComparison = new Long(a.lastModified()).compareTo(
27             new Long(b.lastModified()));
28         if (timeComparison != 0) {
29           return timeComparison;
30         }
31         else {
32           return a.getName().compareTo(b.getName());
33         }
34       }
35     });
36     File nextFile = candidateFiles.get(0); //因为每次获取到的文件处理完都会被标记为已完成，所以直接取拍完序的第一个
37     //修复传输大文件报错文件被修改的BUG
38     this.checkFileCpIsOver(nextFile);//此处被阻塞，直到文件拷贝文件或者超过20秒
39
40     try {
41       // roll the meta file, if needed
42       String nextPath = nextFile.getPath()

  private Optional<FileInfo> getNextFile() {List<File> candidateFiles = Collections.emptyList();if (consumeOrder != ConsumeOrder.RANDOM ||candidateFileIter == null ||!candidateFileIter.hasNext()) {candidateFiles = getCandidateFiles(spoolDirectory.toPath());listFilesCount++;candidateFileIter = candidateFiles.iterator();}if (!candidateFileIter.hasNext()) { // No matching file in spooling directory.return Optional.absent();}File selectedFile = candidateFileIter.next();if (consumeOrder == ConsumeOrder.RANDOM) { // Selected file is random.return openFile(selectedFile);} else if (consumeOrder == ConsumeOrder.YOUNGEST) {for (File candidateFile : candidateFiles) {long compare = selectedFile.lastModified() -candidateFile.lastModified();if (compare == 0) { // ts is same pick smallest lexicographically.selectedFile = smallerLexicographical(selectedFile, candidateFile);} else if (compare < 0) { // candidate is younger (cand-ts > selec-ts)selectedFile = candidateFile;}}} else { // default order is OLDESTfor (File candidateFile : candidateFiles) {long compare = selectedFile.lastModified() -candidateFile.lastModified();if (compare == 0) { // ts is same pick smallest lexicographically.selectedFile = smallerLexicographical(selectedFile, candidateFile);} else if (compare > 0) { // candidate is older (cand-ts < selec-ts).selectedFile = candidateFile;}}}firstTimeRead = true;//修复传输大文件报错文件被修改的BUG
    this.checkFileCpIsOver(selectedFile);//此处被阻塞，直到文件拷贝文件或者超过20秒return openFile(selectedFile);}

 /**** @Title: checkFileCpIsOver* @Description: TODO(用来检查文件拷贝是否完成)* @param @param currentFile    设定文件* @return void    返回类型* @throws*/
private void checkFileCpIsOver(File file) {long modified = file.lastModified();//目前文件的修改时间long length = file.length();//目前文件的大小try {Thread.sleep(1000);//等待1秒钟} catch (InterruptedException e) {// TODO Auto-generated catch block
      e.printStackTrace();}File currentFile = new File(file.getAbsolutePath());int count = 0;//记录循环次数，超过20次，也就是10秒后抛出异常while(currentFile.lastModified() != modified || currentFile.length() != length) {if(count > 20) {String message = "File Copy time too long. please check copy whether exception!" + "\n"+ "File at :" + file.getAbsolutePath() + "\n"+ "File current length is：" + currentFile.lastModified();new IllegalStateException(message);}count++;modified = currentFile.lastModified();length = currentFile.length();try {Thread.sleep(500);//等待500毫秒} catch (InterruptedException e) {// TODO Auto-generated catch block
          e.printStackTrace();}currentFile = new File(file.getAbsolutePath());}//一直到文件传输完成就可以退出
}