有很多答案，但我决定加上我自己的，因为它有点不同。它是基于OOP的;)

我创建了DirectoryCleaner类，每当我需要清理某个目录时，它都会帮助我。

public class DirectoryCleaner {
    private final File mFile;

    public DirectoryCleaner(File file) {
        mFile = file;
    }

    public void clean() {
        if (null == mFile || !mFile.exists() || !mFile.isDirectory()) return;
        for (File file : mFile.listFiles()) {
            delete(file);
        }
    }

    private void delete(File file) {
        if (file.isDirectory()) {
            for (File child : file.listFiles()) {
                delete(child);
            }
        }
        file.delete();

    }
}

可以用下面的方法来解决这个问题:

File dir = new File(Environment.getExternalStorageDirectory(), "your_directory_name");
new DirectoryCleaner(dir).clean();
dir.delete();

从目录中删除所有文件的简单方法:

它是一个通用函数，用于删除目录中的所有图像

deleteAllImageFile(背景);

public static void deleteAllFile(Context context) {
File directory = context.getExternalFilesDir(null);
        if (directory.isDirectory()) {
            for (String fileName: file.list()) {
                new File(file,fileName).delete();
            }
        }    
    } 

看到android.os。FileUtils，它隐藏在API 21上

public static boolean deleteContents(File dir) {
    File[] files = dir.listFiles();
    boolean success = true;
    if (files != null) {
        for (File file : files) {
            if (file.isDirectory()) {
                success &= deleteContents(file);
            }
            if (!file.delete()) {
                Log.w("Failed to delete " + file);
                success = false;
            }
        }
    }
    return success;
}

来源:https://android.googlesource.com/platform/frameworks/base/ + /主/核心/ java / android / os / FileUtils.java # 414

这是另一种(现代)解决方法。

public class FileUtils {
    public static void delete(File fileOrDirectory) {
        if(fileOrDirectory != null && fileOrDirectory.exists()) {
            if(fileOrDirectory.isDirectory() && fileOrDirectory.listFiles() != null) {      
                Arrays.stream(fileOrDirectory.listFiles())
                      .forEach(FileUtils::delete);
            }
            fileOrDirectory.delete();
        }
    }
}

从API 26开始在Android上运行

public class FileUtils {

    public static void delete(File fileOrDirectory)  {
        if(fileOrDirectory != null) {
            delete(fileOrDirectory.toPath());
        }
    }

    public static void delete(Path path)  {
        try {
            if(Files.exists(path)) {
                Files.walk(path)
                        .sorted(Comparator.reverseOrder())
                        .map(Path::toFile)
//                      .peek(System.out::println)
                        .forEach(File::delete);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

如果你不需要递归删除东西，你可以尝试这样做:

File file = new File(context.getExternalFilesDir(null), "");
    if (file != null && file.isDirectory()) {
        File[] files = file.listFiles();
        if(files != null) {
            for(File f : files) {   
                f.delete();
            }
        }
    }

//To delete all the files of a specific folder & subfolder
public static void deleteFiles(File directory, Context c) {
    try {
        for (File file : directory.listFiles()) {
            if (file.isFile()) {
                final ContentResolver contentResolver = c.getContentResolver();
                String canonicalPath;
                try {
                    canonicalPath = file.getCanonicalPath();
                } catch (IOException e) {
                    canonicalPath = file.getAbsolutePath();
                }
                final Uri uri = MediaStore.Files.getContentUri("external");
                final int result = contentResolver.delete(uri,
                        MediaStore.Files.FileColumns.DATA + "=?", new String[]{canonicalPath});
                if (result == 0) {
                    final String absolutePath = file.getAbsolutePath();
                    if (!absolutePath.equals(canonicalPath)) {
                        contentResolver.delete(uri,
                                MediaStore.Files.FileColumns.DATA + "=?", new String[]{absolutePath});
                    }
                }
                if (file.exists()) {
                    file.delete();
                    if (file.exists()) {
                        try {
                            file.getCanonicalFile().delete();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                        if (file.exists()) {
                            c.deleteFile(file.getName());
                        }
                    }
                }
            } else
                deleteFiles(file, c);
        }
    } catch (Exception e) {
    }
}

这是你的解决方案，它也将刷新画廊以及。