19

尝试对从Java 中递归删除目录中java.nio.file.DirectoryNotEmptyException获取的递归删除方法中的偶然问题进行故障排除

代码（归功于@TrevorRobinson）：

static void removeRecursive(Path path) throws IOException {
    Files.walkFileTree(path, new SimpleFileVisitor<Path>() {

        final Logger logger = LoggerFactory.getLogger(this.getClass());
        @Override
        public FileVisitResult visitFile(Path file,
                BasicFileAttributes attrs) throws IOException {
            logger.warn("Deleting " + file.getFileName());
            Files.delete(file);
            logger.warn("DELETED " + file.getFileName());
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult visitFileFailed(Path file, IOException exc) {
            // try to delete the file anyway, even if its attributes could
            // not be read, since delete-only access is theoretically possible
            // I NEVER SEE THIS
            logger.warn("Delete file " + file + " failed", exc);
            try {
                Files.delete(file);
            } catch (IOException e) {
                logger.warn(
                    "Delete file " + file + " failed again", exc);
            }
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult postVisitDirectory(Path dir, IOException exc)
                throws IOException {
            if (exc == null) {
                Files.delete(dir);
                return FileVisitResult.CONTINUE;
            }
            // directory iteration failed; propagate exception
            throw exc;
        }
    });
}

致电：

try {
    removeRecursive(Paths.get(unzipDirPath));
} catch (IOException e) {
    String msg = "Failed to delete folder " + unzipDirPath;
    if (e instanceof java.nio.file.DirectoryNotEmptyException) {
        msg += ". Still contains : ";
        final File[] listFiles = Paths.get(unzipDirPath).toFile().listFiles();
        if (listFiles != null) for (File file : listFiles) {
            msg += file.getAbsolutePath() + "\n";
        }
    }
    log.error(msg, e);
}

打印（20/40 迭代一次）：

22:03:34.190 [http-bio-8080-exec-47] WARN  g.u.d.m.server.servlets.Controller$1 - Deleting batt
22:03:34.192 [http-bio-8080-exec-47] WARN  g.u.d.m.server.servlets.Controller$1 - DELETED batt
22:03:34.192 [http-bio-8080-exec-47] WARN  g.u.d.m.server.servlets.Controller$1 - Deleting wifi
22:03:34.193 [http-bio-8080-exec-47] WARN  g.u.d.m.server.servlets.Controller$1 - DELETED wifi
22:03:34.196 [http-bio-8080-exec-47] ERROR g.u.d.m.s.s.DataCollectionServlet - Failed to delete folder C:\yada\. Still contains : C:\yada\dir\wifi

java.nio.file.DirectoryNotEmptyException: C:\yada\dir
    at sun.nio.fs.WindowsFileSystemProvider.implDelete(WindowsFileSystemProvider.java:265) ~[na:1.7.0_45]
    at sun.nio.fs.AbstractFileSystemProvider.delete(AbstractFileSystemProvider.java:103) ~[na:1.7.0_45]
    at java.nio.file.Files.delete(Files.java:1077) ~[na:1.7.0_45]
    at gr.uoa.di.monitoring.server.servlets.Controller$1.postVisitDirectory(Controller.java:128) ~[Controller$1.class:na]
    at gr.uoa.di.monitoring.server.servlets.Controller$1.postVisitDirectory(Controller.java:1) ~[Controller$1.class:na]
    at java.nio.file.FileTreeWalker.walk(FileTreeWalker.java:224) ~[na:1.7.0_45]
    at java.nio.file.FileTreeWalker.walk(FileTreeWalker.java:199) ~[na:1.7.0_45]
    at java.nio.file.FileTreeWalker.walk(FileTreeWalker.java:69) ~[na:1.7.0_45]
    at java.nio.file.Files.walkFileTree(Files.java:2600) ~[na:1.7.0_45]
    at java.nio.file.Files.walkFileTree(Files.java:2633) ~[na:1.7.0_45]
    at gr.uoa.di.monitoring.server.servlets.Controller.removeRecursive(Controller.java:96) ~[Controller.class:na]
    at gr.uoa.di.monitoring.server.servlets.DataCollectionServlet.doPost(DataCollectionServlet.java:153) ~[DataCollectionServlet.class:na]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:641) [servlet-api.jar:na]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) [servlet-api.jar:na]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) [catalina.jar:7.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) [catalina.jar:7.0.32]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) [catalina.jar:7.0.32]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) [catalina.jar:7.0.32]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) [catalina.jar:7.0.32]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) [catalina.jar:7.0.32]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) [catalina.jar:7.0.32]
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929) [catalina.jar:7.0.32]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) [catalina.jar:7.0.32]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) [catalina.jar:7.0.32]
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002) [tomcat-coyote.jar:7.0.32]
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585) [tomcat-coyote.jar:7.0.32]
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) [tomcat-coyote.jar:7.0.32]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_45]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_45]
    at java.lang.Thread.run(Thread.java:744) [na:1.7.0_45]

请注意，wifi报告为已删除 - 更奇怪的是，有时我会得到：

删除文件夹 C:\yada 失败。仍包含：C:\yada\dir

java.nio.file.DirectoryNotEmptyException: C:\yada\dir

我倾向于得出这样的结论，即有时删除时间太长 - 换句话说，问题在于java.nio.file.Files.delete(Path path)它不会阻塞（所以 C:\yada\dir 到了时候仍然包含文件，有时在我统计它时会被删除） . 那么我该如何解决这个问题呢？

另外：java.nio.file.Files.delete(Path path)必须扔吗？文档状态：

在某些操作系统上，当此 Java 虚拟机或其他程序打开并使用该文件时，可能无法删除该文件。

在这种情况下似乎不需要抛出异常。需要扔吗java.nio.file.Files.delete(Path path)？

4

5 回答 5

15

我遇到了同样的问题，结果发现问题是由代码中其他地方的未关闭目录文件流引起的，该目录与我从中删除内容的目录相同。返回的流对象：

Files.list(Path)

必须关闭，因此如果使用该方法，请务必在代码中使用 try-with-resources 构造。

所以我认为删除时间不会太长，我在重新尝试删除目录之前尝试了等待，但没有任何运气。您自己的程序很可能已锁定该资源。结果是尽管它成功返回，但对它的删除调用没有完成（看起来Windows最终会在您自己的程序释放文件后删除该文件）但是当然包含目录不能被删除，因为这确实还没有空的。

于 2015-09-09T17:41:33.643 回答
3

我知道这是一个非常古老的线程 - 但我遇到了同样的问题，我花了很长时间才修复它。我认为这种不当行为是由时间问题引起的（看起来它只发生在 Windows 上），所以我暂停了 postVisitDirectory 方法。那行得通，这就是我最终想出的：

一种在不抛出 DirectoryNotEmptyException 的情况下执行删除的方法：

private boolean isDeleted(Path dir) throws IOException {
    boolean deleted = false;
    try {
        Files.delete(dir);
        deleted = true;
    } catch (DirectoryNotEmptyException e) {
    // happens sometimes if Windows is too slow to remove children of a directory
    deleted = false;
    }
    return deleted;
}

及其在循环中的使用：

public FileVisitResult postVisitDirectory(Path dir, IOException e) throws IOException {
    if (e == null) {
        int maxTries = 5;
        int count = 0;
        boolean deleted = false;
        do {
            if ((deleted = this.isDeleted(dir))) {
                break;
            } else {
                // wait a bit and try again
                count++;
                try {
                    Thread.sleep(1);
                } catch (InterruptedException e1) {
                    Thread.currentThread().interrupt();
                    break;
                }
            }
        } while (count < maxTries);
        // gone?
        if (!deleted) {
            throw new DirectoryNotEmptyException(dir.toString());
        }
        // go ahead
        return FileVisitResult.CONTINUE;
    }
    throw e;
}

安迪

于 2016-08-09T03:47:03.457 回答
2

我会评论@user3485962 的答案，但没有足够的分数！

这是一个使用 try 的示例，该示例在创建列表后关闭流的资源：

    /**  
     * @param dir The directory to list.
     * @return A list of files and directories in dir.
     * @throws IOException If encountered.
     */
    public static List<Path> getList(Path dir) throws IOException {
        try (Stream<Path> s = Files.list(dir)) {
            return s.collect(Collectors.toList());
        }
    }
于 2019-12-05T09:45:22.717 回答
0

您可以将当前正在迭代的文件的名称临时存储在变量中并在DirectoryNotEmptyException. 发生此异常时，捕获它并抛出您自己的指定文件的异常。

try {
 Files.delete(file);
} catch (DirectoryNotEmptyException  e) {
 throw new MySpecificException(file.getFileName());
}

class MySpecificException extends Exception {
 public MySpecificException() { }

 public MySpecificException(string filename) {
  super(filename);
 }  
}

获取文件名可以通过e.getMessage();

我假设Files.delete()在遇到无法删除的文件时继续删除目录中的文件。如果是这种情况，我的方法仍然有效：只需返回目录中所有文件的列表，而不是目录的文件名。它应该只包含无法删除的文件，并且您仍然有您的解决方案。

于 2013-11-12T17:20:24.790 回答
-1

扩展我上面的评论。

当 Java 在做某事时遇到问题时，它会抛出Exception。与所有其他类型一样，异常可以继承自。API 将指定每个方法抛出的已检查异常。java.io和中的方法java.nio通常会抛出IOException或其中一个孩子。如果您想创建一个方法来告诉您为什么文件操作（在这种情况下是删除）失败，您可以执行以下操作：

@Override
public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException {
       //You don't need to try to delete the file again since this method was called
       //because the deletion failed. Instead...
       if (exc instanceof NoSuchFileException) {
            System.out.println("Could not find the file: " + file);
       } else if (exc instanceof DirectoryNotEmptyException) {
            System.out.println("The directory [+ " file + "] was not empty.");
       } else {
            System.out.println("Could not delete file [" + file
                + "]. There was a problem communicating with the file system");
       }

       return FileVisitResult.CONTINUE;
}

您可以根据需要更改实际的程序响应，但这应该会给您大致的想法。

于 2013-11-12T22:06:56.813 回答