Files class will typically delegate to an instance of this
class.
A file system provider is a concrete implementation of this class that
implements the abstract methods defined by this class. A provider is
identified by a URI scheme. The default provider
is identified by the URI scheme "file". It creates the FileSystem that
provides access to the file systems accessible to the Java virtual machine.
The FileSystems class defines how file system providers are located
and loaded. The default provider is typically a system-default provider but
may be overridden if the system property java.nio.file.spi.DefaultFileSystemProvider is set. In that case, the
provider has a one argument constructor whose formal parameter type is
FileSystemProvider. All other providers have a zero argument constructor
that initializes the provider.
A provider is a factory for one or more FileSystem instances. Each
file system is identified by a URI where the URI's scheme matches
the provider's scheme. The default file system, for example,
is identified by the URI "file:///". A memory-based file system,
for example, may be identified by a URI such as "memory:///?name=logfs".
The newFileSystem method may be used to create a file
system, and the getFileSystem method may be used to
obtain a reference to an existing file system created by the provider. Where
a provider is the factory for a single file system then it is provider dependent
if the file system is created when the provider is initialized, or later when
the newFileSystem method is invoked. In the case of the default
provider, the FileSystem is created when the provider is initialized.
All of the methods in this class are safe for use by multiple concurrent threads.
- Since:
- 1.7
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Constructor Summary
ConstructorsModifierConstructorDescriptionprotectedInitializes a new instance of this class. -
Method Summary
Modifier and TypeMethodDescriptionabstract voidcheckAccess(Path path, AccessMode... modes) Checks the existence, and optionally the accessibility, of a file.abstract voidcopy(Path source, Path target, CopyOption... options) Copy a file to a target file.abstract voidcreateDirectory(Path dir, FileAttribute<?>... attrs) Creates a new directory.voidcreateLink(Path link, Path existing) Creates a new link (directory entry) for an existing file.voidcreateSymbolicLink(Path link, Path target, FileAttribute<?>... attrs) Creates a symbolic link to a target.abstract voidDeletes a file.booleandeleteIfExists(Path path) Deletes a file if it exists.booleanexists(Path path, LinkOption... options) Tests whether a file exists.abstract <V extends FileAttributeView>
VgetFileAttributeView(Path path, Class<V> type, LinkOption... options) Returns a file attribute view of a given type.abstract FileStoregetFileStore(Path path) Returns theFileStorerepresenting the file store where a file is located.abstract FileSystemgetFileSystem(URI uri) Returns an existingFileSystemcreated by this provider.abstract PathReturn aPathobject by converting the givenURI.abstract StringReturns the URI scheme that identifies this provider.static List<FileSystemProvider> Returns a list of the installed file system providers.abstract booleanTells whether or not a file is considered hidden.abstract booleanisSameFile(Path path, Path path2) Tests if two paths locate the same file.abstract voidmove(Path source, Path target, CopyOption... options) Move or rename a file to a target file.newAsynchronousFileChannel(Path path, Set<? extends OpenOption> options, ExecutorService executor, FileAttribute<?>... attrs) Opens or creates a file for reading and/or writing, returning an asynchronous file channel to access the file.abstract SeekableByteChannelnewByteChannel(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs) Opens or creates a file, returning a seekable byte channel to access the file.abstract DirectoryStream<Path> newDirectoryStream(Path dir, DirectoryStream.Filter<? super Path> filter) Opens a directory, returning aDirectoryStreamto iterate over the entries in the directory.newFileChannel(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs) Opens or creates a file for reading and/or writing, returning a file channel to access the file.abstract FileSystemnewFileSystem(URI uri, Map<String, ?> env) Constructs a newFileSystemobject identified by a URI.newFileSystem(Path path, Map<String, ?> env) Constructs a newFileSystemto access the contents of a file as a file system.newInputStream(Path path, OpenOption... options) Opens a file, returning an input stream to read from the file.newOutputStream(Path path, OpenOption... options) Opens or creates a file, returning an output stream that may be used to write bytes to the file.abstract <A extends BasicFileAttributes>
AreadAttributes(Path path, Class<A> type, LinkOption... options) Reads a file's attributes as a bulk operation.readAttributes(Path path, String attributes, LinkOption... options) Reads a set of file attributes as a bulk operation.<A extends BasicFileAttributes>
AreadAttributesIfExists(Path path, Class<A> type, LinkOption... options) Reads a file's attributes as a bulk operation if it exists.readSymbolicLink(Path link) Reads the target of a symbolic link.abstract voidsetAttribute(Path path, String attribute, Object value, LinkOption... options) Sets the value of a file attribute.
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Constructor Details
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FileSystemProvider
protected FileSystemProvider()Initializes a new instance of this class.During construction a provider may safely access files associated with the default provider but care needs to be taken to avoid circular loading of other installed providers. If circular loading of installed providers is detected then an unspecified error is thrown.
- Throws:
SecurityException- If a security manager has been installed and it deniesRuntimePermission("fileSystemProvider")
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-
Method Details
-
installedProviders
Returns a list of the installed file system providers.The first invocation of this method causes the default provider to be initialized (if not already initialized) and loads any other installed providers as described by the
FileSystemsclass.- Returns:
- An unmodifiable list of the installed file system providers. The list contains at least one element, that is the default file system provider
- Throws:
ServiceConfigurationError- When an error occurs while loading a service provider
-
getScheme
Returns the URI scheme that identifies this provider.- Returns:
- The URI scheme
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newFileSystem
Constructs a newFileSystemobject identified by a URI. This method is invoked by theFileSystems.newFileSystem(URI,Map)method to open a new file system identified by a URI.The
uriparameter is an absolute, hierarchical URI, with a scheme equal (without regard to case) to the scheme supported by this provider. The exact form of the URI is highly provider dependent. Theenvparameter is a map of provider specific properties to configure the file system.This method throws
FileSystemAlreadyExistsExceptionif the file system already exists because it was previously created by an invocation of this method. Once a file system isclosedit is provider-dependent if the provider allows a new file system to be created with the same URI as a file system it previously created.- Parameters:
uri- URI referenceenv- A map of provider specific properties to configure the file system; may be empty- Returns:
- A new file system
- Throws:
IllegalArgumentException- If the pre-conditions for theuriparameter aren't met, or theenvparameter does not contain properties required by the provider, or a property value is invalidIOException- An I/O error occurs creating the file systemSecurityException- If a security manager is installed and it denies an unspecified permission required by the file system provider implementationFileSystemAlreadyExistsException- If the file system has already been created
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getFileSystem
Returns an existingFileSystemcreated by this provider.This method returns a reference to a
FileSystemthat was created by invoking thenewFileSystem(URI,Map)method. File systems created thenewFileSystem(Path,Map)method are not returned by this method. The file system is identified by itsURI. Its exact form is highly provider dependent. In the case of the default provider the URI's path component is"/"and the authority, query and fragment components are undefined (Undefined components are represented bynull).Once a file system created by this provider is
closedit is provider-dependent if this method returns a reference to the closed file system or throwsFileSystemNotFoundException. If the provider allows a new file system to be created with the same URI as a file system it previously created then this method throws the exception if invoked after the file system is closed (and before a new instance is created by thenewFileSystemmethod).If a security manager is installed then a provider implementation may require to check a permission before returning a reference to an existing file system. In the case of the
defaultfile system, no permission check is required.- Parameters:
uri- URI reference- Returns:
- The file system
- Throws:
IllegalArgumentException- If the pre-conditions for theuriparameter aren't metFileSystemNotFoundException- If the file system does not existSecurityException- If a security manager is installed and it denies an unspecified permission.
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getPath
Return aPathobject by converting the givenURI. The resultingPathis associated with aFileSystemthat already exists or is constructed automatically.The exact form of the URI is file system provider dependent. In the case of the default provider, the URI scheme is
"file"and the given URI has a non-empty path component, and undefined query, and fragment components. The resultingPathis associated with the defaultdefaultFileSystem.If a security manager is installed then a provider implementation may require to check a permission. In the case of the
defaultfile system, no permission check is required.- Parameters:
uri- The URI to convert- Returns:
- The resulting
Path - Throws:
IllegalArgumentException- If the URI scheme does not identify this provider or other preconditions on the uri parameter do not holdFileSystemNotFoundException- The file system, identified by the URI, does not exist and cannot be created automaticallySecurityException- If a security manager is installed and it denies an unspecified permission.
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newFileSystem
Constructs a newFileSystemto access the contents of a file as a file system.This method is intended for specialized providers of pseudo file systems where the contents of one or more files is treated as a file system. The
envparameter is a map of provider specific properties to configure the file system.If this provider does not support the creation of such file systems or if the provider does not recognize the file type of the given file then it throws
UnsupportedOperationException. The default implementation of this method throwsUnsupportedOperationException.- Parameters:
path- The path to the fileenv- A map of provider specific properties to configure the file system; may be empty- Returns:
- A new file system
- Throws:
UnsupportedOperationException- If this provider does not support access to the contents as a file system or it does not recognize the file type of the given fileIllegalArgumentException- If theenvparameter does not contain properties required by the provider, or a property value is invalidIOException- If an I/O error occursSecurityException- If a security manager is installed and it denies an unspecified permission.
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newInputStream
Opens a file, returning an input stream to read from the file. This method works in exactly the manner specified by theFiles.newInputStream(java.nio.file.Path, java.nio.file.OpenOption...)method.The default implementation of this method opens a channel to the file as if by invoking the
newByteChannel(java.nio.file.Path, java.util.Set<? extends java.nio.file.OpenOption>, java.nio.file.attribute.FileAttribute<?>...)method and constructs a stream that reads bytes from the channel. This method should be overridden where appropriate.- Parameters:
path- the path to the file to openoptions- options specifying how the file is opened- Returns:
- a new input stream
- Throws:
IllegalArgumentException- if an invalid combination of options is specifiedUnsupportedOperationException- if an unsupported option is specifiedIOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, thecheckReadmethod is invoked to check read access to the file.
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newOutputStream
Opens or creates a file, returning an output stream that may be used to write bytes to the file. This method works in exactly the manner specified by theFiles.newOutputStream(java.nio.file.Path, java.nio.file.OpenOption...)method.The default implementation of this method opens a channel to the file as if by invoking the
newByteChannel(java.nio.file.Path, java.util.Set<? extends java.nio.file.OpenOption>, java.nio.file.attribute.FileAttribute<?>...)method and constructs a stream that writes bytes to the channel. This method should be overridden where appropriate.- Parameters:
path- the path to the file to open or createoptions- options specifying how the file is opened- Returns:
- a new output stream
- Throws:
IllegalArgumentException- ifoptionscontains an invalid combination of optionsUnsupportedOperationException- if an unsupported option is specifiedIOException- if an I/O error occursFileAlreadyExistsException- If a file of that name already exists and theCREATE_NEWoption is specified (optional specific exception)SecurityException- In the case of the default provider, and a security manager is installed, thecheckWritemethod is invoked to check write access to the file. ThecheckDeletemethod is invoked to check delete access if the file is opened with theDELETE_ON_CLOSEoption.
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newFileChannel
public FileChannel newFileChannel(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs) throws IOException Opens or creates a file for reading and/or writing, returning a file channel to access the file. This method works in exactly the manner specified by theFileChannel.openmethod. A provider that does not support all the features required to construct a file channel throwsUnsupportedOperationException. The default provider is required to support the creation of file channels. When not overridden, the default implementation throwsUnsupportedOperationException.- Parameters:
path- the path of the file to open or createoptions- options specifying how the file is openedattrs- an optional list of file attributes to set atomically when creating the file- Returns:
- a new file channel
- Throws:
IllegalArgumentException- If the set contains an invalid combination of optionsUnsupportedOperationException- If this provider that does not support creating file channels, or an unsupported open option or file attribute is specifiedFileAlreadyExistsException- If a file of that name already exists and theCREATE_NEWoption is specified and the file is being opened for writing (optional specific exception)IOException- If an I/O error occursSecurityException- In the case of the default file system, theSecurityManager.checkRead(String)method is invoked to check read access if the file is opened for reading. TheSecurityManager.checkWrite(String)method is invoked to check write access if the file is opened for writing
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newAsynchronousFileChannel
public AsynchronousFileChannel newAsynchronousFileChannel(Path path, Set<? extends OpenOption> options, ExecutorService executor, FileAttribute<?>... attrs) throws IOException Opens or creates a file for reading and/or writing, returning an asynchronous file channel to access the file. This method works in exactly the manner specified by theAsynchronousFileChannel.openmethod. A provider that does not support all the features required to construct an asynchronous file channel throwsUnsupportedOperationException. The default provider is required to support the creation of asynchronous file channels. When not overridden, the default implementation of this method throwsUnsupportedOperationException.- Parameters:
path- the path of the file to open or createoptions- options specifying how the file is openedexecutor- the thread pool ornullto associate the channel with the default thread poolattrs- an optional list of file attributes to set atomically when creating the file- Returns:
- a new asynchronous file channel
- Throws:
IllegalArgumentException- If the set contains an invalid combination of optionsUnsupportedOperationException- If this provider that does not support creating asynchronous file channels, or an unsupported open option or file attribute is specifiedFileAlreadyExistsException- If a file of that name already exists and theCREATE_NEWoption is specified and the file is being opened for writing (optional specific exception)IOException- If an I/O error occursSecurityException- In the case of the default file system, theSecurityManager.checkRead(String)method is invoked to check read access if the file is opened for reading. TheSecurityManager.checkWrite(String)method is invoked to check write access if the file is opened for writing
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newByteChannel
public abstract SeekableByteChannel newByteChannel(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs) throws IOException Opens or creates a file, returning a seekable byte channel to access the file. This method works in exactly the manner specified by theFiles.newByteChannel(Path,Set,FileAttribute[])method.- Parameters:
path- the path to the file to open or createoptions- options specifying how the file is openedattrs- an optional list of file attributes to set atomically when creating the file- Returns:
- a new seekable byte channel
- Throws:
IllegalArgumentException- if the set contains an invalid combination of optionsUnsupportedOperationException- if an unsupported open option is specified or the array contains attributes that cannot be set atomically when creating the fileFileAlreadyExistsException- If a file of that name already exists and theCREATE_NEWoption is specified and the file is being opened for writing (optional specific exception)IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, thecheckReadmethod is invoked to check read access to the path if the file is opened for reading. ThecheckWritemethod is invoked to check write access to the path if the file is opened for writing. ThecheckDeletemethod is invoked to check delete access if the file is opened with theDELETE_ON_CLOSEoption.
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newDirectoryStream
public abstract DirectoryStream<Path> newDirectoryStream(Path dir, DirectoryStream.Filter<? super Path> filter) throws IOException Opens a directory, returning aDirectoryStreamto iterate over the entries in the directory. This method works in exactly the manner specified by theFiles.newDirectoryStream(java.nio.file.Path, java.nio.file.DirectoryStream.Filter)method.- Parameters:
dir- the path to the directoryfilter- the directory stream filter- Returns:
- a new and open
DirectoryStreamobject - Throws:
NotDirectoryException- if the file could not otherwise be opened because it is not a directory (optional specific exception)IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, thecheckReadmethod is invoked to check read access to the directory.
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createDirectory
Creates a new directory. This method works in exactly the manner specified by theFiles.createDirectory(java.nio.file.Path, java.nio.file.attribute.FileAttribute<?>...)method.- Parameters:
dir- the directory to createattrs- an optional list of file attributes to set atomically when creating the directory- Throws:
UnsupportedOperationException- if the array contains an attribute that cannot be set atomically when creating the directoryFileAlreadyExistsException- if a directory could not otherwise be created because a file of that name already exists (optional specific exception)IOException- if an I/O error occurs or the parent directory does not existSecurityException- In the case of the default provider, and a security manager is installed, thecheckWritemethod is invoked to check write access to the new directory.
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createSymbolicLink
public void createSymbolicLink(Path link, Path target, FileAttribute<?>... attrs) throws IOException Creates a symbolic link to a target. This method works in exactly the manner specified by theFiles.createSymbolicLink(java.nio.file.Path, java.nio.file.Path, java.nio.file.attribute.FileAttribute<?>...)method.The default implementation of this method throws
UnsupportedOperationException.- Parameters:
link- the path of the symbolic link to createtarget- the target of the symbolic linkattrs- the array of attributes to set atomically when creating the symbolic link- Throws:
UnsupportedOperationException- if the implementation does not support symbolic links or the array contains an attribute that cannot be set atomically when creating the symbolic linkFileAlreadyExistsException- if a file with the name already exists (optional specific exception)IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, it deniesLinkPermission("symbolic")or itscheckWritemethod denies write access to the path of the symbolic link.
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createLink
Creates a new link (directory entry) for an existing file. This method works in exactly the manner specified by theFiles.createLink(java.nio.file.Path, java.nio.file.Path)method.The default implementation of this method throws
UnsupportedOperationException.- Parameters:
link- the link (directory entry) to createexisting- a path to an existing file- Throws:
UnsupportedOperationException- if the implementation does not support adding an existing file to a directoryFileAlreadyExistsException- if the entry could not otherwise be created because a file of that name already exists (optional specific exception)IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, it deniesLinkPermission("hard")or itscheckWritemethod denies write access to either the link or the existing file.
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delete
Deletes a file. This method works in exactly the manner specified by theFiles.delete(java.nio.file.Path)method.- Parameters:
path- the path to the file to delete- Throws:
NoSuchFileException- if the file does not exist (optional specific exception)DirectoryNotEmptyException- if the file is a directory and could not otherwise be deleted because the directory is not empty (optional specific exception)IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, theSecurityManager.checkDelete(String)method is invoked to check delete access to the file
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deleteIfExists
Deletes a file if it exists. This method works in exactly the manner specified by theFiles.deleteIfExists(java.nio.file.Path)method.The default implementation of this method simply invokes
delete(java.nio.file.Path)ignoring theNoSuchFileExceptionwhen the file does not exist. It may be overridden where appropriate.- Parameters:
path- the path to the file to delete- Returns:
trueif the file was deleted by this method;falseif the file could not be deleted because it did not exist- Throws:
DirectoryNotEmptyException- if the file is a directory and could not otherwise be deleted because the directory is not empty (optional specific exception)IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, theSecurityManager.checkDelete(String)method is invoked to check delete access to the file
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readSymbolicLink
Reads the target of a symbolic link. This method works in exactly the manner specified by theFiles.readSymbolicLink(java.nio.file.Path)method.The default implementation of this method throws
UnsupportedOperationException.- Parameters:
link- the path to the symbolic link- Returns:
- The target of the symbolic link
- Throws:
UnsupportedOperationException- if the implementation does not support symbolic linksNotLinkException- if the target could otherwise not be read because the file is not a symbolic link (optional specific exception)IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, it checks thatFilePermissionhas been granted with the "readlink" action to read the link.
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copy
Copy a file to a target file. This method works in exactly the manner specified by theFiles.copy(Path,Path,CopyOption[])method except that both the source and target paths must be associated with this provider.- Parameters:
source- the path to the file to copytarget- the path to the target fileoptions- options specifying how the copy should be done- Throws:
UnsupportedOperationException- if the array contains a copy option that is not supportedFileAlreadyExistsException- if the target file exists but cannot be replaced because theREPLACE_EXISTINGoption is not specified (optional specific exception)DirectoryNotEmptyException- theREPLACE_EXISTINGoption is specified but the file cannot be replaced because it is a non-empty directory (optional specific exception)IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, thecheckReadmethod is invoked to check read access to the source file, thecheckWriteis invoked to check write access to the target file. If a symbolic link is copied the security manager is invoked to checkLinkPermission("symbolic").
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move
Move or rename a file to a target file. This method works in exactly the manner specified by theFiles.move(java.nio.file.Path, java.nio.file.Path, java.nio.file.CopyOption...)method except that both the source and target paths must be associated with this provider.- Parameters:
source- the path to the file to movetarget- the path to the target fileoptions- options specifying how the move should be done- Throws:
UnsupportedOperationException- if the array contains a copy option that is not supportedFileAlreadyExistsException- if the target file exists but cannot be replaced because theREPLACE_EXISTINGoption is not specified (optional specific exception)DirectoryNotEmptyException- theREPLACE_EXISTINGoption is specified but the file cannot be replaced because it is a non-empty directory (optional specific exception)AtomicMoveNotSupportedException- if the options array contains theATOMIC_MOVEoption but the file cannot be moved as an atomic file system operation.IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, thecheckWritemethod is invoked to check write access to both the source and target file.
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isSameFile
Tests if two paths locate the same file. This method works in exactly the manner specified by theFiles.isSameFile(java.nio.file.Path, java.nio.file.Path)method.- Parameters:
path- one path to the filepath2- the other path- Returns:
trueif, and only if, the two paths locate the same file- Throws:
IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, thecheckReadmethod is invoked to check read access to both files.
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isHidden
Tells whether or not a file is considered hidden. This method works in exactly the manner specified by theFiles.isHidden(java.nio.file.Path)method.This method is invoked by the
isHiddenmethod.- Parameters:
path- the path to the file to test- Returns:
trueif the file is considered hidden- Throws:
IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, thecheckReadmethod is invoked to check read access to the file.
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getFileStore
Returns theFileStorerepresenting the file store where a file is located. This method works in exactly the manner specified by theFiles.getFileStore(java.nio.file.Path)method.- Parameters:
path- the path to the file- Returns:
- the file store where the file is stored
- Throws:
IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, thecheckReadmethod is invoked to check read access to the file, and in addition it checksRuntimePermission("getFileStoreAttributes")
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checkAccess
Checks the existence, and optionally the accessibility, of a file.This method may be used by the
isReadable,isWritableandisExecutablemethods to check the accessibility of a file.This method checks the existence of a file and that this Java virtual machine has appropriate privileges that would allow it access the file according to all of access modes specified in the
modesparameter as follows:Value Description READChecks that the file exists and that the Java virtual machine has permission to read the file. WRITEChecks that the file exists and that the Java virtual machine has permission to write to the file, EXECUTEChecks that the file exists and that the Java virtual machine has permission to executethe file. The semantics may differ when checking access to a directory. For example, on UNIX systems, checking forEXECUTEaccess checks that the Java virtual machine has permission to search the directory in order to access file or subdirectories.If the
modesparameter is of length zero, then the existence of the file is checked.This method follows symbolic links if the file referenced by this object is a symbolic link. Depending on the implementation, this method may require to read file permissions, access control lists, or other file attributes in order to check the effective access to the file. To determine the effective access to a file may require access to several attributes and so in some implementations this method may not be atomic with respect to other file system operations.
- Parameters:
path- the path to the file to checkmodes- The access modes to check; may have zero elements- Throws:
UnsupportedOperationException- an implementation is required to support checking forREAD,WRITE, andEXECUTEaccess. This exception is specified to allow for theAccessenum to be extended in future releases.NoSuchFileException- if a file does not exist (optional specific exception)AccessDeniedException- the requested access would be denied or the access cannot be determined because the Java virtual machine has insufficient privileges or other reasons. (optional specific exception)IOException- if an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, thecheckReadis invoked when checking read access to the file or only the existence of the file, thecheckWriteis invoked when checking write access to the file, andcheckExecis invoked when checking execute access.
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getFileAttributeView
public abstract <V extends FileAttributeView> V getFileAttributeView(Path path, Class<V> type, LinkOption... options) Returns a file attribute view of a given type. This method works in exactly the manner specified by theFiles.getFileAttributeView(java.nio.file.Path, java.lang.Class<V>, java.nio.file.LinkOption...)method.- Type Parameters:
V- TheFileAttributeViewtype- Parameters:
path- the path to the filetype- theClassobject corresponding to the file attribute viewoptions- options indicating how symbolic links are handled- Returns:
- a file attribute view of the specified type, or
nullif the attribute view type is not available
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readAttributes
public abstract <A extends BasicFileAttributes> A readAttributes(Path path, Class<A> type, LinkOption... options) throws IOException Reads a file's attributes as a bulk operation. This method works in exactly the manner specified by theFiles.readAttributes(Path,Class,LinkOption[])method.- Type Parameters:
A- TheBasicFileAttributestype- Parameters:
path- the path to the filetype- theClassof the file attributes required to readoptions- options indicating how symbolic links are handled- Returns:
- the file attributes
- Throws:
UnsupportedOperationException- if an attributes of the given type are not supportedIOException- if an I/O error occursSecurityException- In the case of the default provider, a security manager is installed, itscheckReadmethod is invoked to check read access to the file
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readAttributes
public abstract Map<String,Object> readAttributes(Path path, String attributes, LinkOption... options) throws IOException Reads a set of file attributes as a bulk operation. This method works in exactly the manner specified by theFiles.readAttributes(Path,String,LinkOption[])method.- Parameters:
path- the path to the fileattributes- the attributes to readoptions- options indicating how symbolic links are handled- Returns:
- a map of the attributes returned; may be empty. The map's keys are the attribute names, its values are the attribute values
- Throws:
UnsupportedOperationException- if the attribute view is not availableIllegalArgumentException- if no attributes are specified or an unrecognized attributes is specifiedIOException- If an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, itscheckReadmethod denies read access to the file. If this method is invoked to read security sensitive attributes then the security manager may be invoked to check for additional permissions.
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setAttribute
public abstract void setAttribute(Path path, String attribute, Object value, LinkOption... options) throws IOException Sets the value of a file attribute. This method works in exactly the manner specified by theFiles.setAttribute(java.nio.file.Path, java.lang.String, java.lang.Object, java.nio.file.LinkOption...)method.- Parameters:
path- the path to the fileattribute- the attribute to setvalue- the attribute valueoptions- options indicating how symbolic links are handled- Throws:
UnsupportedOperationException- if the attribute view is not availableIllegalArgumentException- if the attribute name is not specified, or is not recognized, or the attribute value is of the correct type but has an inappropriate valueClassCastException- If the attribute value is not of the expected type or is a collection containing elements that are not of the expected typeIOException- If an I/O error occursSecurityException- In the case of the default provider, and a security manager is installed, itscheckWritemethod denies write access to the file. If this method is invoked to set security sensitive attributes then the security manager may be invoked to check for additional permissions.
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exists
Tests whether a file exists. This method works in exactly the manner specified by theFiles.exists(Path, LinkOption...)method.- Implementation Requirements:
- The default implementation of this method invokes the
checkAccess(Path, AccessMode...)method when symbolic links are followed. If the optionNOFOLLOW_LINKSis present then symbolic links are not followed and the methodreadAttributes(Path, Class, LinkOption...)is called to determine whether a file exists. - Parameters:
path- the path to the file to testoptions- options indicating how symbolic links are handled- Returns:
trueif the file exists;falseif the file does not exist or its existence cannot be determined.- Throws:
SecurityException- In the case of the default provider, theSecurityManager.checkRead(String)is invoked to check read access to the file.- Since:
- 20
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readAttributesIfExists
public <A extends BasicFileAttributes> A readAttributesIfExists(Path path, Class<A> type, LinkOption... options) throws IOException Reads a file's attributes as a bulk operation if it exists.The
typeparameter is the type of the attributes required and this method returns an instance of that type if supported. All implementations support a basic set of file attributes and so invoking this method with atypeparameter ofBasicFileAttributes.classwill not throwUnsupportedOperationException.The
optionsarray may be used to indicate how symbolic links are handled for the case that the file is a symbolic link. By default, symbolic links are followed and the file attribute of the final target of the link is read. If the optionNOFOLLOW_LINKSis present then symbolic links are not followed.It is implementation specific if all file attributes are read as an atomic operation with respect to other file system operations.
- Implementation Requirements:
- The default implementation of this method invokes the
readAttributes(Path, Class, LinkOption...)method to read the file's attributes. - Type Parameters:
A- TheBasicFileAttributestype- Parameters:
path- the path to the filetype- theClassof the file attributes required to readoptions- options indicating how symbolic links are handled- Returns:
- the file attributes or null if the file does not exist
- Throws:
UnsupportedOperationException- if an attributes of the given type are not supportedIOException- if an I/O error occursSecurityException- In the case of the default provider, a security manager is installed, itscheckReadmethod is invoked to check read access to the file. If this method is invoked to read security sensitive attributes then the security manager may be invoked to check for additional permissions.- Since:
- 20
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