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package java.nio.file.spi;
import java.nio.file.Path;
import java.io.IOException;
A file type detector for probing a file to guess its file type.
A file type detector is a concrete implementation of this class, has a
zero-argument constructor, and implements the abstract methods specified
below.
The means by which a file type detector determines the file type is
highly implementation specific. A simple implementation might examine the
file extension (a convention used in some platforms) and map it to
a file type. In other cases, the file type may be stored as a file attribute or the bytes in a
file may be examined to guess its file type.
See Also: - probeContentType.probeContentType(Path)
Since: 1.7
/**
* A file type detector for probing a file to guess its file type.
*
* <p> A file type detector is a concrete implementation of this class, has a
* zero-argument constructor, and implements the abstract methods specified
* below.
*
* <p> The means by which a file type detector determines the file type is
* highly implementation specific. A simple implementation might examine the
* <em>file extension</em> (a convention used in some platforms) and map it to
* a file type. In other cases, the file type may be stored as a file <a
* href="../attribute/package-summary.html"> attribute</a> or the bytes in a
* file may be examined to guess its file type.
*
* @see java.nio.file.Files#probeContentType(Path)
*
* @since 1.7
*/
public abstract class FileTypeDetector {
private static Void checkPermission() {
SecurityManager sm = System.getSecurityManager();
if (sm != null)
sm.checkPermission(new RuntimePermission("fileTypeDetector"));
return null;
}
private FileTypeDetector(Void ignore) { }
Initializes a new instance of this class.
Throws: - SecurityException – If a security manager has been installed and it denies
RuntimePermission("fileTypeDetector")
/**
* Initializes a new instance of this class.
*
* @throws SecurityException
* If a security manager has been installed and it denies
* {@link RuntimePermission}{@code ("fileTypeDetector")}
*/
protected FileTypeDetector() {
this(checkPermission());
}
Probes the given file to guess its content type.
The means by which this method determines the file type is highly
implementation specific. It may simply examine the file name, it may use
a file attribute,
or it may examines bytes in the file.
The probe result is the string form of the value of a
Multipurpose Internet Mail Extension (MIME) content type as
defined by RFC 2045:
Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet
Message Bodies. The string must be parsable according to the
grammar in the RFC 2045.
Params: - path –
the path to the file to probe
Throws: - IOException –
An I/O error occurs
- SecurityException – If the implementation requires to access the file, and a security manager is installed, and it denies an unspecified permission required by a file system provider implementation. If the file reference is associated with the default file system provider then the
SecurityManager.checkRead(String) method is invoked to check read access to the file.
See Also: Returns: The content type or null if the file type is not recognized
/**
* Probes the given file to guess its content type.
*
* <p> The means by which this method determines the file type is highly
* implementation specific. It may simply examine the file name, it may use
* a file <a href="../attribute/package-summary.html">attribute</a>,
* or it may examines bytes in the file.
*
* <p> The probe result is the string form of the value of a
* Multipurpose Internet Mail Extension (MIME) content type as
* defined by <a href="http://www.ietf.org/rfc/rfc2045.txt"><i>RFC 2045:
* Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet
* Message Bodies</i></a>. The string must be parsable according to the
* grammar in the RFC 2045.
*
* @param path
* the path to the file to probe
*
* @return The content type or {@code null} if the file type is not
* recognized
*
* @throws IOException
* An I/O error occurs
* @throws SecurityException
* If the implementation requires to access the file, and a
* security manager is installed, and it denies an unspecified
* permission required by a file system provider implementation.
* If the file reference is associated with the default file system
* provider then the {@link SecurityManager#checkRead(String)} method
* is invoked to check read access to the file.
*
* @see java.nio.file.Files#probeContentType
*/
public abstract String probeContentType(Path path)
throws IOException;
}