javax.activation.CommandMap Maven / Gradle / Ivy
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package javax.activation;
import java.util.Map;
import java.util.WeakHashMap;
/**
* The CommandMap class provides an interface to a registry of
* command objects available in the system.
* Developers are expected to either use the CommandMap
* implementation included with this package (MailcapCommandMap) or
* develop their own. Note that some of the methods in this class are
* abstract.
*/
public abstract class CommandMap {
private static CommandMap defaultCommandMap = null;
private static Map map =
new WeakHashMap();
/**
* Get the default CommandMap.
*
*
* - In cases where a CommandMap instance has been previously set
* to some value (via setDefaultCommandMap)
* return the CommandMap.
*
-
* In cases where no CommandMap has been set, the CommandMap
* creates an instance of
MailcapCommandMap and
* set that to the default, returning its value.
*
*
*
* @return the CommandMap
*/
public static synchronized CommandMap getDefaultCommandMap() {
if (defaultCommandMap != null)
return defaultCommandMap;
// fetch per-thread-context-class-loader default
ClassLoader tccl = SecuritySupport.getContextClassLoader();
CommandMap def = map.get(tccl);
if (def == null) {
def = new MailcapCommandMap();
map.put(tccl, def);
}
return def;
}
/**
* Set the default CommandMap. Reset the CommandMap to the default by
* calling this method with null.
*
* @param commandMap The new default CommandMap.
* @exception SecurityException if the caller doesn't have permission
* to change the default
*/
public static synchronized void setDefaultCommandMap(CommandMap commandMap) {
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 = CommandMap.class.getClassLoader();
if (cl == null || cl.getParent() == null ||
cl != commandMap.getClass().getClassLoader()) {
throw ex;
}
}
}
// remove any per-thread-context-class-loader CommandMap
map.remove(SecuritySupport.getContextClassLoader());
defaultCommandMap = commandMap;
}
/**
* Get the preferred command list from a MIME Type. The actual semantics
* are determined by the implementation of the CommandMap.
*
* @param mimeType the MIME type
* @return the CommandInfo classes that represent the command Beans.
*/
abstract public CommandInfo[] getPreferredCommands(String mimeType);
/**
* Get the preferred command list from a MIME Type. The actual semantics
* are determined by the implementation of the CommandMap.
*
* The DataSource provides extra information, such as
* the file name, that a CommandMap implementation may use to further
* refine the list of commands that are returned. The implementation
* in this class simply calls the getPreferredCommands
* method that ignores this argument.
*
* @param mimeType the MIME type
* @param ds a DataSource for the data
* @return the CommandInfo classes that represent the command Beans.
* @since JAF 1.1
*/
public CommandInfo[] getPreferredCommands(String mimeType, DataSource ds) {
return getPreferredCommands(mimeType);
}
/**
* Get all the available commands for this type. This method
* should return all the possible commands for this MIME type.
*
* @param mimeType the MIME type
* @return the CommandInfo objects representing all the commands.
*/
abstract public CommandInfo[] getAllCommands(String mimeType);
/**
* Get all the available commands for this type. This method
* should return all the possible commands for this MIME type.
*
* The DataSource provides extra information, such as
* the file name, that a CommandMap implementation may use to further
* refine the list of commands that are returned. The implementation
* in this class simply calls the getAllCommands
* method that ignores this argument.
*
* @param mimeType the MIME type
* @param ds a DataSource for the data
* @return the CommandInfo objects representing all the commands.
* @since JAF 1.1
*/
public CommandInfo[] getAllCommands(String mimeType, DataSource ds) {
return getAllCommands(mimeType);
}
/**
* Get the default command corresponding to the MIME type.
*
* @param mimeType the MIME type
* @param cmdName the command name
* @return the CommandInfo corresponding to the command.
*/
abstract public CommandInfo getCommand(String mimeType, String cmdName);
/**
* Get the default command corresponding to the MIME type.
*
* The DataSource provides extra information, such as
* the file name, that a CommandMap implementation may use to further
* refine the command that is chosen. The implementation
* in this class simply calls the getCommand
* method that ignores this argument.
*
* @param mimeType the MIME type
* @param cmdName the command name
* @param ds a DataSource for the data
* @return the CommandInfo corresponding to the command.
* @since JAF 1.1
*/
public CommandInfo getCommand(String mimeType, String cmdName,
DataSource ds) {
return getCommand(mimeType, cmdName);
}
/**
* Locate a DataContentHandler that corresponds to the MIME type.
* The mechanism and semantics for determining this are determined
* by the implementation of the particular CommandMap.
*
* @param mimeType the MIME type
* @return the DataContentHandler for the MIME type
*/
abstract public DataContentHandler createDataContentHandler(String
mimeType);
/**
* Locate a DataContentHandler that corresponds to the MIME type.
* The mechanism and semantics for determining this are determined
* by the implementation of the particular CommandMap.
*
* The DataSource provides extra information, such as
* the file name, that a CommandMap implementation may use to further
* refine the choice of DataContentHandler. The implementation
* in this class simply calls the createDataContentHandler
* method that ignores this argument.
*
* @param mimeType the MIME type
* @param ds a DataSource for the data
* @return the DataContentHandler for the MIME type
* @since JAF 1.1
*/
public DataContentHandler createDataContentHandler(String mimeType,
DataSource ds) {
return createDataContentHandler(mimeType);
}
/**
* Get all the MIME types known to this command map.
* If the command map doesn't support this operation,
* null is returned.
*
* @return array of MIME types as strings, or null if not supported
* @since JAF 1.1
*/
public String[] getMimeTypes() {
return null;
}
}