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Interface JavaFileManager

All Superinterfaces:
AutoCloseable, Closeable, Flushable, OptionChecker
All Known Subinterfaces:
StandardJavaFileManager
All Known Implementing Classes:
ForwardingJavaFileManager
public interface JavaFileManager
extends Closeable, Flushable, OptionChecker

File manager for tools operating on Java™ programming language source and class files. In this context, file means an abstraction of regular files and other sources of data.

When constructing new JavaFileObjects, the file manager must determine where to create them. For example, if a file manager manages regular files on a file system, it would most likely have a current/working directory to use as default location when creating or finding files. A number of hints can be provided to a file manager as to where to create files. Any file manager might choose to ignore these hints.

Some methods in this interface use class names. Such class names must be given in the Java Virtual Machine internal form of fully qualified class and interface names. For convenience '.' and '/' are interchangeable. The internal form is defined in chapter four of The Java™ Virtual Machine Specification.

Discussion: this means that the names "java/lang.package-info", "java/lang/package-info", "java.lang.package-info", are valid and equivalent. Compare to binary name as defined in The Java™ Language Specification, section 13.1 "The Form of a Binary".

The case of names is significant. All names should be treated as case-sensitive. For example, some file systems have case-insensitive, case-aware file names. File objects representing such files should take care to preserve case by using File.getCanonicalFile() or similar means. If the system is not case-aware, file objects must use other means to preserve case.

Relative names: some methods in this interface use relative names. A relative name is a non-null, non-empty sequence of path segments separated by '/'. '.' or '..' are invalid path segments. A valid relative name must match the "path-rootless" rule of RFC 3986, section 3.3. Informally, this should be true: 

URI.create(relativeName).normalize().getPath().equals(relativeName)

All methods in this interface might throw a SecurityException.

An object of this interface is not required to support multi-threaded access, that is, be synchronized. However, it must support concurrent access to different file objects created by this object.

Implementation note: a consequence of this requirement is that a trivial implementation of output to a JarOutputStream is not a sufficient implementation. That is, rather than creating a JavaFileObject that returns the JarOutputStream directly, the contents must be cached until closed and then written to the JarOutputStream.

Unless explicitly allowed, all methods in this interface might throw a NullPointerException if given a null argument.

Since:
1.6
See Also:
JavaFileObject, FileObject

Nested Classes

Nested Classes
Modifier and Type Interface and Description
static interface  JavaFileManager.Location

Interface for locations of file objects.

Methods

getClassLoader

ClassLoader getClassLoader(JavaFileManager.Location location)

Gets a class loader for loading plug-ins from the given location. For example, to load annotation processors, a compiler will request a class loader for the ANNOTATION_PROCESSOR_PATH location.

Parameters:
location - a location
Returns:
a class loader for the given location; or null if loading plug-ins from the given location is disabled or if the location is not known
Throws:
SecurityException - if a class loader can not be created in the current security context
IllegalStateException - if close() has been called and this file manager cannot be reopened

list

Iterable<JavaFileObject> list(JavaFileManager.Location location,
                              String packageName,
                              Set<JavaFileObject.Kind> kinds,
                              boolean recurse)
                       throws IOException

Lists all file objects matching the given criteria in the given location. List file objects in "subpackages" if recurse is true.

Note: even if the given location is unknown to this file manager, it may not return null. Also, an unknown location may not cause an exception.

Parameters:
location - a location
packageName - a package name
kinds - return objects only of these kinds
recurse - if true include "subpackages"
Returns:
an Iterable of file objects matching the given criteria
Throws:
IOException - if an I/O error occurred, or if close() has been called and this file manager cannot be reopened
IllegalStateException - if close() has been called and this file manager cannot be reopened

inferBinaryName

String inferBinaryName(JavaFileManager.Location location,
                       JavaFileObject file)

Infers a binary name of a file object based on a location. The binary name returned might not be a valid binary name according to The Java™ Language Specification.

Parameters:
location - a location
file - a file object
Returns:
a binary name or null the file object is not found in the given location
Throws:
IllegalStateException - if close() has been called and this file manager cannot be reopened

isSameFile

boolean isSameFile(FileObject a,
                   FileObject b)

Compares two file objects and return true if they represent the same underlying object.

Parameters:
a - a file object
b - a file object
Returns:
true if the given file objects represent the same underlying object
Throws:
IllegalArgumentException - if either of the arguments were created with another file manager and this file manager does not support foreign file objects

handleOption

boolean handleOption(String current,
                     Iterator<String> remaining)

Handles one option. If current is an option to this file manager it will consume any arguments to that option from remaining and return true, otherwise return false.

Parameters:
current - current option
remaining - remaining options
Returns:
true if this option was handled by this file manager, false otherwise
Throws:
IllegalArgumentException - if this option to this file manager is used incorrectly
IllegalStateException - if close() has been called and this file manager cannot be reopened

hasLocation

boolean hasLocation(JavaFileManager.Location location)

Determines if a location is known to this file manager.

Parameters:
location - a location
Returns:
true if the location is known

getJavaFileForInput

JavaFileObject getJavaFileForInput(JavaFileManager.Location location,
                                   String className,
                                   JavaFileObject.Kind kind)
                            throws IOException

Gets a file object for input representing the specified class of the specified kind in the given location.

Parameters:
location - a location
className - the name of a class
kind - the kind of file, must be one of SOURCE or CLASS
Returns:
a file object, might return null if the file does not exist
Throws:
IllegalArgumentException - if the location is not known to this file manager and the file manager does not support unknown locations, or if the kind is not valid
IOException - if an I/O error occurred, or if close() has been called and this file manager cannot be reopened
IllegalStateException - if close() has been called and this file manager cannot be reopened

getJavaFileForOutput

JavaFileObject getJavaFileForOutput(JavaFileManager.Location location,
                                    String className,
                                    JavaFileObject.Kind kind,
                                    FileObject sibling)
                             throws IOException

Gets a file object for output representing the specified class of the specified kind in the given location.

Optionally, this file manager might consider the sibling as a hint for where to place the output. The exact semantics of this hint is unspecified. The JDK compiler, javac, for example, will place class files in the same directories as originating source files unless a class file output directory is provided. To facilitate this behavior, javac might provide the originating source file as sibling when calling this method.

Parameters:
location - a location
className - the name of a class
kind - the kind of file, must be one of SOURCE or CLASS
sibling - a file object to be used as hint for placement; might be null
Returns:
a file object for output
Throws:
IllegalArgumentException - if sibling is not known to this file manager, or if the location is not known to this file manager and the file manager does not support unknown locations, or if the kind is not valid
IOException - if an I/O error occurred, or if close() has been called and this file manager cannot be reopened
IllegalStateException - close() has been called and this file manager cannot be reopened

getFileForInput

FileObject getFileForInput(JavaFileManager.Location location,
                           String packageName,
                           String relativeName)
                    throws IOException

Gets a file object for input representing the specified relative name in the specified package in the given location.

If the returned object represents a source or class file, it must be an instance of JavaFileObject.

Informally, the file object returned by this method is located in the concatenation of the location, package name, and relative name. For example, to locate the properties file "resources/compiler.properties" in the package "com.sun.tools.javac" in the SOURCE_PATH location, this method might be called like so: 

getFileForInput(SOURCE_PATH, "com.sun.tools.javac", "resources/compiler.properties");

If the call was executed on Windows, with SOURCE_PATH set to "C:\Documents and Settings\UncleBob\src\share\classes", a valid result would be a file object representing the file "C:\Documents and Settings\UncleBob\src\share\classes\com\sun\tools\javac\resources\compiler.properties".

Parameters:
location - a location
packageName - a package name
relativeName - a relative name
Returns:
a file object, might return null if the file does not exist
Throws:
IllegalArgumentException - if the location is not known to this file manager and the file manager does not support unknown locations, or if relativeName is not valid
IOException - if an I/O error occurred, or if close() has been called and this file manager cannot be reopened
IllegalStateException - if close() has been called and this file manager cannot be reopened

getFileForOutput

FileObject getFileForOutput(JavaFileManager.Location location,
                            String packageName,
                            String relativeName,
                            FileObject sibling)
                     throws IOException

Gets a file object for output representing the specified relative name in the specified package in the given location.

Optionally, this file manager might consider the sibling as a hint for where to place the output. The exact semantics of this hint is unspecified. The JDK compiler, javac, for example, will place class files in the same directories as originating source files unless a class file output directory is provided. To facilitate this behavior, javac might provide the originating source file as sibling when calling this method.

If the returned object represents a source or class file, it must be an instance of JavaFileObject.

Informally, the file object returned by this method is located in the concatenation of the location, package name, and relative name or next to the sibling argument. See getFileForInput for an example.

Parameters:
location - a location
packageName - a package name
relativeName - a relative name
sibling - a file object to be used as hint for placement; might be null
Returns:
a file object
Throws:
IllegalArgumentException - if sibling is not known to this file manager, or if the location is not known to this file manager and the file manager does not support unknown locations, or if relativeName is not valid
IOException - if an I/O error occurred, or if close() has been called and this file manager cannot be reopened
IllegalStateException - if close() has been called and this file manager cannot be reopened

flush

void flush()
    throws IOException

Flushes any resources opened for output by this file manager directly or indirectly. Flushing a closed file manager has no effect.

Specified by:
flush in interface Flushable
Throws:
IOException - if an I/O error occurred
See Also:
close()

close

void close()
    throws IOException

Releases any resources opened by this file manager directly or indirectly. This might render this file manager useless and the effect of subsequent calls to methods on this object or any objects obtained through this object is undefined unless explicitly allowed. However, closing a file manager which has already been closed has no effect.

Specified by:
close in interface AutoCloseable
Specified by:
close in interface Closeable
Throws:
IOException - if an I/O error occurred
See Also:
flush()

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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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