FileUtils (Alluxio Parent 305-SNAPSHOT API)

java.lang.Object
- alluxio.util.io.FileUtils

```
@ThreadSafe
public final class FileUtils
extends Object
```
Provides utility methods for working with files and directories. By convention, methods take file path strings as parameters.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static void`	`changeLocalFileGroup(String path, String group)` Changes the local file's group.
`static void`	`changeLocalFilePermission(String filePath, String perms)` Changes local file's permission.
`static void`	`changeLocalFileToFullPermission(String filePath)` Changes local file's permission to be "rwxrwxrwx".
`static void`	`changeLocalFileUser(String path, String user)` Changes the local file's user.
`static void`	`createBlockPath(String path, String workerDataFolderPermissions)` Creates the local block path and all the parent directories.
`static void`	`createDir(String path)` Creates an empty directory and its intermediate directories if necessary.
`static void`	`createFile(String filePath)` Creates an empty file and its intermediate directories if necessary.
`static boolean`	`createStorageDirPath(String path, String workerDataFolderPermissions)` Creates the storage directory path, including any necessary but nonexistent parent directories.
`static void`	`delete(String path)` Deletes the file or directory.
`static void`	`deleteIfExists(String path)` Deletes the file or directory, if it exists.
`static void`	`deletePathRecursively(String path)` Deletes a file or a directory, recursively if it is a directory.
`static boolean`	`exists(String path)` Checks if a path exists.
`static short`	`getLocalFileMode(String filePath)` Gets local file's permission mode.
`static boolean`	`isStorageDirAccessible(String path)` Checks if a storage directory path is accessible.
`static void`	`move(String srcPath, String dstPath)` Moves file from one place to another, can across storage devices (e.g., from memory to SSD) when `File.renameTo(java.io.File)` may not work.
`static void`	`setLocalDirStickyBit(String dir)` Sticky bit can be set primarily on directories in UNIX / Linux.
`static Set<PosixFilePermission>`	`translateModeToPosixPermissions(int mode)` Translate mode to posix file permissions.
`static short`	`translatePosixPermissionToMode(Set<PosixFilePermission> permission)` Translate posix file permissions to short mode.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - changeLocalFileGroup
```
public static void changeLocalFileGroup(String path,
                                        String group)
                                 throws IOException
```
    Changes the local file's group.
    
    Parameters:
    
    path - that will change owner
    
    group - the new group
    
    Throws:
    
    IOException
  - changeLocalFilePermission
```
public static void changeLocalFilePermission(String filePath,
                                             String perms)
```
    Changes local file's permission.
    
    Parameters:
    
    filePath - that will change permission
    
    perms - the permission, e.g. "rwxr--r--"
  - changeLocalFileToFullPermission
```
public static void changeLocalFileToFullPermission(String filePath)
```
    Changes local file's permission to be "rwxrwxrwx".
    
    Parameters:
    
    filePath - that will change permission
  - getLocalFileMode
```
public static short getLocalFileMode(String filePath)
                              throws IOException
```
    Gets local file's permission mode.
    
    Parameters:
    
    filePath - the file path
    
    Returns:
    
    the file mode in short, e.g. 0777
    
    Throws:
    
    IOException
  - translatePosixPermissionToMode
```
public static short translatePosixPermissionToMode(Set<PosixFilePermission> permission)
```
    Translate posix file permissions to short mode.
    
    Parameters:
    
    permission - posix file permission
    
    Returns:
    
    mode for file
  - translateModeToPosixPermissions
```
public static Set<PosixFilePermission> translateModeToPosixPermissions(int mode)
```
    Translate mode to posix file permissions.
    
    Parameters:
    
    mode - the file mode
    
    Returns:
    
    posix file permissions
  - changeLocalFileUser
```
public static void changeLocalFileUser(String path,
                                       String user)
                                throws IOException
```
    Changes the local file's user.
    
    Parameters:
    
    path - that will change owner
    
    user - the new user
    
    Throws:
    
    IOException
  - setLocalDirStickyBit
```
public static void setLocalDirStickyBit(String dir)
```
    Sticky bit can be set primarily on directories in UNIX / Linux. If the sticky bit of is enabled on a directory, only the owner and the root user can delete / rename the files or directories within that directory. No one else can delete other users data in this directory(Where sticky bit is set). This is a security measure to avoid deletion of folders and their content (sub-folders and files), though other users have full permissions. Setting the sticky bit of a file is a no-op.
    
    Parameters:
    
    dir - absolute dir path to set the sticky bit
  - createBlockPath
```
public static void createBlockPath(String path,
                                   String workerDataFolderPermissions)
```
    Creates the local block path and all the parent directories. Also, sets the appropriate permissions.
    
    Parameters:
    
    path - the path of the block
    
    workerDataFolderPermissions - The permissions to set on the worker's data folder
  - move
```
public static void move(String srcPath,
                        String dstPath)
                 throws IOException
```
    Moves file from one place to another, can across storage devices (e.g., from memory to SSD) when File.renameTo(java.io.File) may not work.
    
    Parameters:
    
    srcPath - pathname string of source file
    
    dstPath - pathname string of destination file
    
    Throws:
    
    IOException
  - delete
```
public static void delete(String path)
```
    Deletes the file or directory.
    
    Parameters:
    
    path - pathname string of file or directory
  - deleteIfExists
```
public static void deleteIfExists(String path)
```
    Deletes the file or directory, if it exists.
    
    Parameters:
    
    path - pathname string of file or directory
  - deletePathRecursively
```
public static void deletePathRecursively(String path)
                                  throws IOException
```
    Deletes a file or a directory, recursively if it is a directory. If the path does not exist, nothing happens.
    
    Parameters:
    
    path - pathname to be deleted
    
    Throws:
    
    IOException
  - createStorageDirPath
```
public static boolean createStorageDirPath(String path,
                                           String workerDataFolderPermissions)
```
    Creates the storage directory path, including any necessary but nonexistent parent directories. If the directory already exists, do nothing. Also, appropriate directory permissions (w/ StickyBit) are set.
    
    Parameters:
    
    path - storage directory path to create
    
    workerDataFolderPermissions - the permissions to set for the worker's data folder
    
    Returns:
    
    true if the directory is created and false if the directory already exists
  - createFile
```
public static void createFile(String filePath)
```
    Creates an empty file and its intermediate directories if necessary.
    
    Parameters:
    
    filePath - pathname string of the file to create
  - createDir
```
public static void createDir(String path)
                      throws IOException
```
    Creates an empty directory and its intermediate directories if necessary.
    
    Parameters:
    
    path - path of the directory to create
    
    Throws:
    
    IOException
  - exists
```
public static boolean exists(String path)
```
    Checks if a path exists.
    
    Parameters:
    
    path - the given path
    
    Returns:
    
    true if path exists, false otherwise
  - isStorageDirAccessible
```
public static boolean isStorageDirAccessible(String path)
```
    Checks if a storage directory path is accessible.
    
    Parameters:
    
    path - the given path
    
    Returns:
    
    true if path exists, false otherwise

Class FileUtils

Method Summary

Methods inherited from class java.lang.Object

Method Detail

changeLocalFileGroup

changeLocalFilePermission

changeLocalFileToFullPermission

getLocalFileMode

translatePosixPermissionToMode

translateModeToPosixPermissions

changeLocalFileUser

setLocalDirStickyBit

createBlockPath

move

delete

deleteIfExists

deletePathRecursively

createStorageDirPath

createFile

createDir

exists

isStorageDirAccessible