问题
Is there a way to delete entire directories recursively in Java?
In the normal case it is possible to delete an empty directory. However when it comes to deleting entire directories with contents, it is not that simple anymore.
How do you delete entire directories with contents in Java?
回答1:
You should check out Apache's commons-io. It has a FileUtils class that will do what you want.
FileUtils.deleteDirectory(new File("directory"));
回答2:
With Java 7, we can finally do this with reliable symlink detection. (I don't consider Apache's commons-io to have reliable symlink detection at this time, as it doesn't handle links on Windows created with mklink.)
For the sake of history, here's a pre-Java 7 answer, which follows symlinks.
void delete(File f) throws IOException {
if (f.isDirectory()) {
for (File c : f.listFiles())
delete(c);
}
if (!f.delete())
throw new FileNotFoundException("Failed to delete file: " + f);
}
回答3:
In Java 7+ you can use Files class. Code is very simple:
Path directory = Paths.get("/tmp");
Files.walkFileTree(directory, new SimpleFileVisitor<Path>() {
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
Files.delete(file);
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
Files.delete(dir);
return FileVisitResult.CONTINUE;
}
});
回答4:
Java 7 added support for walking directories with symlink handling:
import java.nio.file.*;
public static void removeRecursive(Path path) throws IOException
{
Files.walkFileTree(path, new SimpleFileVisitor<Path>()
{
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
throws IOException
{
Files.delete(file);
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException
{
// try to delete the file anyway, even if its attributes
// could not be read, since delete-only access is
// theoretically possible
Files.delete(file);
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException
{
if (exc == null)
{
Files.delete(dir);
return FileVisitResult.CONTINUE;
}
else
{
// directory iteration failed; propagate exception
throw exc;
}
}
});
}
I use this as a fallback from platform-specific methods (in this untested code):
public static void removeDirectory(Path directory) throws IOException
{
// does nothing if non-existent
if (Files.exists(directory))
{
try
{
// prefer OS-dependent directory removal tool
if (SystemUtils.IS_OS_WINDOWS)
Processes.execute("%ComSpec%", "/C", "RD /S /Q \"" + directory + '"');
else if (SystemUtils.IS_OS_UNIX)
Processes.execute("/bin/rm", "-rf", directory.toString());
}
catch (ProcessExecutionException | InterruptedException e)
{
// fallback to internal implementation on error
}
if (Files.exists(directory))
removeRecursive(directory);
}
}
(SystemUtils is from Apache Commons Lang. Processes is private but its behavior should be obvious.)
回答5:
One-liner solution (Java8) to delete all files and directories recursively including starting directory:
Files.walk(Paths.get("c:/dir_to_delete/"))
.map(Path::toFile)
.sorted((o1, o2) -> -o1.compareTo(o2))
.forEach(File::delete);
We use a comparator for reversed order, otherwise File::delete won't be able to delete possibly non-empty directory. So, if you want to keep directories and only delete files just remove the comparator in sorted() or remove sorting completely and add files filter:
Files.walk(Paths.get("c:/dir_to_delete/"))
.filter(Files::isRegularFile)
.map(Path::toFile)
.forEach(File::delete);
回答6:
Just saw my solution is more or less the same as erickson's, just packaged as a static method. Drop this somewhere, it's much lighter weight than installing all of Apache Commons for something that (as you can see) is quite simple.
public class FileUtils {
/**
* By default File#delete fails for non-empty directories, it works like "rm".
* We need something a little more brutual - this does the equivalent of "rm -r"
* @param path Root File Path
* @return true iff the file and all sub files/directories have been removed
* @throws FileNotFoundException
*/
public static boolean deleteRecursive(File path) throws FileNotFoundException{
if (!path.exists()) throw new FileNotFoundException(path.getAbsolutePath());
boolean ret = true;
if (path.isDirectory()){
for (File f : path.listFiles()){
ret = ret && deleteRecursive(f);
}
}
return ret && path.delete();
}
}
回答7:
A solution with a stack and without recursive methods:
File dir = new File("/path/to/dir");
File[] currList;
Stack<File> stack = new Stack<File>();
stack.push(dir);
while (! stack.isEmpty()) {
if (stack.lastElement().isDirectory()) {
currList = stack.lastElement().listFiles();
if (currList.length > 0) {
for (File curr: currList) {
stack.push(curr);
}
} else {
stack.pop().delete();
}
} else {
stack.pop().delete();
}
}
回答8:
Guava had Files.deleteRecursively(File) supported until Guava 9.
From Guava 10:
Deprecated. This method suffers from poor symlink detection and race conditions. This functionality can be supported suitably only by shelling out to an operating system command such as
rm -rfordel /s. This method is scheduled to be removed from Guava in Guava release 11.0.
Therefore, there is no such method in Guava 11.
回答9:
If you have Spring, you can use FileSystemUtils.deleteRecursively:
import org.springframework.util.FileSystemUtils;
boolean success = FileSystemUtils.deleteRecursively(new File("directory"));
回答10:
for(Path p : Files.walk(directoryToDelete).
sorted((a, b) -> b.compareTo(a)). // reverse; files before dirs
toArray(Path[]::new))
{
Files.delete(p);
}
Or if you want to handle the IOException:
Files.walk(directoryToDelete).
sorted((a, b) -> b.compareTo(a)). // reverse; files before dirs
forEach(p -> {
try { Files.delete(p); }
catch(IOException e) { /* ... */ }
});
回答11:
public void deleteRecursive(File path){
File[] c = path.listFiles();
System.out.println("Cleaning out folder:" + path.toString());
for (File file : c){
if (file.isDirectory()){
System.out.println("Deleting file:" + file.toString());
deleteRecursive(file);
file.delete();
} else {
file.delete();
}
}
path.delete();
}
回答12:
static public void deleteDirectory(File path)
{
if (path == null)
return;
if (path.exists())
{
for(File f : path.listFiles())
{
if(f.isDirectory())
{
deleteDirectory(f);
f.delete();
}
else
{
f.delete();
}
}
path.delete();
}
}
回答13:
Two ways to fail with symlinks and the above code... and don't know the solution.
Way #1
Run this to create a test:
echo test > testfile
mkdir dirtodelete
ln -s badlink dirtodelete/badlinktodelete
Here you see your test file and test directory:
$ ls testfile dirtodelete
testfile
dirtodelete:
linktodeleteThen run your commons-io deleteDirectory(). It crashes saying the file is not found. Not sure what the other examples do here. The Linux rm command would simply delete the link, and rm -r on the directory would also.
Exception in thread "main" java.io.FileNotFoundException: File does not exist: /tmp/dirtodelete/linktodeleteWay #2
Run this to create a test:
mkdir testdir
echo test > testdir/testfile
mkdir dirtodelete
ln -s ../testdir dirtodelete/dirlinktodelete
Here you see your test file and test directory:
$ ls dirtodelete testdir
dirtodelete:
dirlinktodelete
testdir:
testfile
Then run your commons-io deleteDirectory() or the example code people posted. It deletes not only the directory, but your testfile which is outside the directory being deleted. (It dereferences the directory implicitly, and deletes the contents). rm -r would delete the link only. You need to use something like this delete the dereferenced files: "find -L dirtodelete -type f -exec rm {} \;".
$ ls dirtodelete testdir
ls: cannot access dirtodelete: No such file or directory
testdir:回答14:
You could use:
org.apache.commons.io.FileUtils.deleteQuietly(destFile);
Deletes a file, never throwing an exception. If file is a directory, delete it and all sub-directories. The difference between File.delete() and this method are: A directory to be deleted does not have to be empty. No exceptions are thrown when a file or directory cannot be deleted.
回答15:
An optimal solution that handles exception consistently with the approach that an exception thrown from a method should always describe what that method was trying (and failed) to do:
private void deleteRecursive(File f) throws Exception {
try {
if (f.isDirectory()) {
for (File c : f.listFiles()) {
deleteRecursive(c);
}
}
if (!f.delete()) {
throw new Exception("Delete command returned false for file: " + f);
}
}
catch (Exception e) {
throw new Exception("Failed to delete the folder: " + f, e);
}
}
回答16:
In legacy projects, I need to create native Java code. I create this code similar to Paulitex code. See that:
public class FileHelper {
public static boolean delete(File fileOrFolder) {
boolean result = true;
if(fileOrFolder.isDirectory()) {
for (File file : fileOrFolder.listFiles()) {
result = result && delete(file);
}
}
result = result && fileOrFolder.delete();
return result;
}
}
And the unit test:
public class FileHelperTest {
@Before
public void setup() throws IOException {
new File("FOLDER_TO_DELETE/SUBFOLDER").mkdirs();
new File("FOLDER_TO_DELETE/SUBFOLDER_TWO").mkdirs();
new File("FOLDER_TO_DELETE/SUBFOLDER_TWO/TEST_FILE.txt").createNewFile();
}
@Test
public void deleteFolderWithFiles() {
File folderToDelete = new File("FOLDER_TO_DELETE");
Assert.assertTrue(FileHelper.delete(folderToDelete));
Assert.assertFalse(new File("FOLDER_TO_DELETE").exists());
}
}
回答17:
Here is a bare bones main method that accepts a command line argument, you may need to append your own error checking or mold it to how you see fit.
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
public class DeleteFiles {
/**
* @param intitial arguments take in a source to read from and a
* destination to read to
*/
public static void main(String[] args)
throws FileNotFoundException,IOException {
File src = new File(args[0]);
if (!src.exists() ) {
System.out.println("FAILURE!");
}else{
// Gathers files in directory
File[] a = src.listFiles();
for (int i = 0; i < a.length; i++) {
//Sends files to recursive deletion method
fileDelete(a[i]);
}
// Deletes original source folder
src.delete();
System.out.println("Success!");
}
}
/**
* @param srcFile Source file to examine
* @throws FileNotFoundException if File not found
* @throws IOException if File not found
*/
private static void fileDelete(File srcFile)
throws FileNotFoundException, IOException {
// Checks if file is a directory
if (srcFile.isDirectory()) {
//Gathers files in directory
File[] b = srcFile.listFiles();
for (int i = 0; i < b.length; i++) {
//Recursively deletes all files and sub-directories
fileDelete(b[i]);
}
// Deletes original sub-directory file
srcFile.delete();
} else {
srcFile.delete();
}
}
}
I hope that helps!
回答18:
Below code recursively delete all contents in a given folder.
boolean deleteDirectory(File directoryToBeDeleted) {
File[] allContents = directoryToBeDeleted.listFiles();
if (allContents != null) {
for (File file : allContents) {
deleteDirectory(file);
}
}
return directoryToBeDeleted.delete();
}
回答19:
Maybe a solution for this problem might be to reimplement the delete method of the File class using the code from erickson's answer:
public class MyFile extends File {
... <- copy constructor
public boolean delete() {
if (f.isDirectory()) {
for (File c : f.listFiles()) {
return new MyFile(c).delete();
}
} else {
return f.delete();
}
}
}
回答20:
Without Commons IO and < Java SE 7
public static void deleteRecursive(File path){
path.listFiles(new FileFilter() {
@Override
public boolean accept(File pathname) {
if (pathname.isDirectory()) {
pathname.listFiles(this);
pathname.delete();
} else {
pathname.delete();
}
return false;
}
});
path.delete();
}
回答21:
While files can easily be deleted using file.delete(), directories are required to be empty to be deleted. Use recursion to do this easily. For example:
public static void clearFolders(String[] args) {
for(String st : args){
File folder = new File(st);
if (folder.isDirectory()) {
File[] files = folder.listFiles();
if(files!=null) {
for(File f: files) {
if (f.isDirectory()){
clearFolders(new String[]{f.getAbsolutePath()});
f.delete();
} else {
f.delete();
}
}
}
}
}
}
回答22:
i coded this routine that has 3 safety criteria for safer use.
package ch.ethz.idsc.queuey.util;
import java.io.File;
import java.io.IOException;
/** recursive file/directory deletion
*
* safety from erroneous use is enhanced by three criteria
* 1) checking the depth of the directory tree T to be deleted
* against a permitted upper bound "max_depth"
* 2) checking the number of files to be deleted #F
* against a permitted upper bound "max_count"
* 3) if deletion of a file or directory fails, the process aborts */
public final class FileDelete {
/** Example: The command
* FileDelete.of(new File("/user/name/myapp/recordings/log20171024"), 2, 1000);
* deletes given directory with sub directories of depth of at most 2,
* and max number of total files less than 1000. No files are deleted
* if directory tree exceeds 2, or total of files exceed 1000.
*
* abort criteria are described at top of class
*
* @param file
* @param max_depth
* @param max_count
* @return
* @throws Exception if criteria are not met */
public static FileDelete of(File file, int max_depth, int max_count) throws IOException {
return new FileDelete(file, max_depth, max_count);
}
// ---
private final File root;
private final int max_depth;
private int removed = 0;
/** @param root file or a directory. If root is a file, the file will be deleted.
* If root is a directory, the directory tree will be deleted.
* @param max_depth of directory visitor
* @param max_count of files to delete
* @throws IOException */
private FileDelete(final File root, final int max_depth, final int max_count) throws IOException {
this.root = root;
this.max_depth = max_depth;
// ---
final int count = visitRecursively(root, 0, false);
if (count <= max_count) // abort criteria 2)
visitRecursively(root, 0, true);
else
throw new IOException("more files to be deleted than allowed (" + max_count + "<=" + count + ") in " + root);
}
private int visitRecursively(final File file, final int depth, final boolean delete) throws IOException {
if (max_depth < depth) // enforce depth limit, abort criteria 1)
throw new IOException("directory tree exceeds permitted depth");
// ---
int count = 0;
if (file.isDirectory()) // if file is a directory, recur
for (File entry : file.listFiles())
count += visitRecursively(entry, depth + 1, delete);
++count; // count file as visited
if (delete) {
final boolean deleted = file.delete();
if (!deleted) // abort criteria 3)
throw new IOException("cannot delete " + file.getAbsolutePath());
++removed;
}
return count;
}
public int deletedCount() {
return removed;
}
public void printNotification() {
int count = deletedCount();
if (0 < count)
System.out.println("deleted " + count + " file(s) in " + root);
}
}
回答23:
Well, let's assume an example,
import java.io.File;
import java.io.IOException;
public class DeleteDirectory
{
private static final String folder = "D:/project/java";
public static void main(String[] args) throws IOException
{
File fl = new File(folder);
if(!fl.exists()) // checking if directory exists
{
System.out.println("Sorry!! directory doesn't exist.");
}
else
{
DeleteDirectory dd = new DeleteDirectory();
dd.deleteDirectory(fl);
}
}
public void deleteDirectory(File file) throws IOException
{
if(file.isDirectory())
{
if(file.list().length == 0)
{
deleteEmptyDirectory(file); // here if directory is empty delete we are deleting
}
else
{
File fe[] = file.listFiles();
for(File deleteFile : fe)
{
deleteDirectory(deleteFile); // recursive call
}
if(file.list().length == 0)
{
deleteEmptyDirectory(file);
}
}
}
else
{
file.delete();
System.out.println("File deleted : " + file.getAbsolutePath());
}
}
private void deleteEmptyDirectory(File fi)
{
fi.delete();
System.out.println("Directory deleted : " + fi.getAbsolutePath());
}
}
For more information refer below resources
Delete directory
回答24:
rm -rf was much more performant than FileUtils.deleteDirectory.
After extensive benchmarking, we found that using rm -rf was multiple times faster than using FileUtils.deleteDirectory.
Of course, if you have a small or simple directory, it won't matter but in our case we had multiple gigabytes and deeply nested sub directories where it would take over 10 minutes with FileUtils.deleteDirectory and only 1 minute with rm -rf.
Here's our rough Java implementation to do that:
// Delete directory given and all subdirectories and files (i.e. recursively).
//
static public boolean deleteDirectory( File file ) throws IOException, InterruptedException {
if ( file.exists() ) {
String deleteCommand = "rm -rf " + file.getAbsolutePath();
Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec( deleteCommand );
process.waitFor();
return true;
}
return false;
}
Worth trying if you're dealing with large or complex directories.
来源：https://stackoverflow.com/questions/779519/delete-directories-recursively-in-java