javax.activation.FileTypeMap Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package javax.activation;
import java.io.File;
import java.util.Map;
import java.util.WeakHashMap;
/**
* The FileTypeMap is an abstract class that provides a data typing
* interface for files. Implementations of this class will
* implement the getContentType methods which will derive a content
* type from a file name or a File object. FileTypeMaps could use any
* scheme to determine the data type, from examining the file extension
* of a file (like the MimetypesFileTypeMap) to opening the file and
* trying to derive its type from the contents of the file. The
* FileDataSource class uses the default FileTypeMap (a MimetypesFileTypeMap
* unless changed) to determine the content type of files.
*
* @see javax.activation.FileTypeMap
* @see javax.activation.FileDataSource
* @see javax.activation.MimetypesFileTypeMap
*/
public abstract class FileTypeMap {
private static FileTypeMap defaultMap = null;
private static Map map =
new WeakHashMap();
/**
* The default constructor.
*/
public FileTypeMap() {
super();
}
/**
* Return the type of the file object. This method should
* always return a valid MIME type.
*
* @param file A file to be typed.
* @return The content type.
*/
abstract public String getContentType(File file);
/**
* Return the type of the file passed in. This method should
* always return a valid MIME type.
*
* @param filename the pathname of the file.
* @return The content type.
*/
abstract public String getContentType(String filename);
/**
* Sets the default FileTypeMap for the system. This instance
* will be returned to callers of getDefaultFileTypeMap.
*
* @param fileTypeMap The FileTypeMap.
* @exception SecurityException if the caller doesn't have permission
* to change the default
*/
public static synchronized void setDefaultFileTypeMap(FileTypeMap fileTypeMap) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
try {
// if it's ok with the SecurityManager, it's ok with me...
security.checkSetFactory();
} catch (SecurityException ex) {
// otherwise, we also allow it if this code and the
// factory come from the same (non-system) class loader (e.g.,
// the JAF classes were loaded with the applet classes).
ClassLoader cl = FileTypeMap.class.getClassLoader();
if (cl == null || cl.getParent() == null ||
cl != fileTypeMap.getClass().getClassLoader())
throw ex;
}
}
// remove any per-thread-context-class-loader FileTypeMap
map.remove(SecuritySupport.getContextClassLoader());
defaultMap = fileTypeMap;
}
/**
* Return the default FileTypeMap for the system.
* If setDefaultFileTypeMap was called, return
* that instance, otherwise return an instance of
* MimetypesFileTypeMap.
*
* @return The default FileTypeMap
* @see javax.activation.FileTypeMap#setDefaultFileTypeMap
*/
public static synchronized FileTypeMap getDefaultFileTypeMap() {
if (defaultMap != null)
return defaultMap;
// fetch per-thread-context-class-loader default
ClassLoader tccl = SecuritySupport.getContextClassLoader();
FileTypeMap def = map.get(tccl);
if (def == null) {
def = new MimetypesFileTypeMap();
map.put(tccl, def);
}
return def;
}
}