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MailcapCommandMap (Java EE 5 SDK) - Java Platform, Enterprise Edition v5.0 API Specifications

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javax.activation
Class MailcapCommandMap

java.lang.Object
  extended by javax.activation.CommandMap
      extended by javax.activation.MailcapCommandMap

public class MailcapCommandMap
extends CommandMap

MailcapCommandMap extends the CommandMap abstract class. It implements a CommandMap whose configuration is based on mailcap files (RFC 1524). The MailcapCommandMap can be configured both programmatically and via configuration files.

Mailcap file search order:

The MailcapCommandMap looks in various places in the user's system for mailcap file entries. When requests are made to search for commands in the MailcapCommandMap, it searches mailcap files in the following order:

  1. Programatically added entries to the MailcapCommandMap instance.
  2. The file .mailcap in the user's home directory.
  3. The file <java.home>/lib/mailcap.
  4. The file or resources named META-INF/mailcap.
  5. The file or resource named META-INF/mailcap.default (usually found only in the activation.jar file).

Mailcap file format:

Mailcap files must conform to the mailcap file specification (RFC 1524, A User Agent Configuration Mechanism For Multimedia Mail Format Information). The file format consists of entries corresponding to particular MIME types. In general, the specification specifies applications for clients to use when they themselves cannot operate on the specified MIME type. The MailcapCommandMap extends this specification by using a parameter mechanism in mailcap files that allows JavaBeans(tm) components to be specified as corresponding to particular commands for a MIME type.

When a mailcap file is parsed, the MailcapCommandMap recognizes certain parameter signatures, specifically those parameter names that begin with x-java-. The MailcapCommandMap uses this signature to find command entries for inclusion into its registries. Parameter names with the form x-java-<name> are read by the MailcapCommandMap as identifying a command with the name name. When the name is content-handler the MailcapCommandMap recognizes the class signified by this parameter as a DataContentHandler. All other commands are handled generically regardless of command name. The command implementation is specified by a fully qualified class name of a JavaBean(tm) component. For example; a command for viewing some data can be specified as: x-java-view=com.foo.ViewBean.

When the command name is fallback-entry, the value of the command may be true or false. An entry for a MIME type that includes a parameter of x-java-fallback-entry=true defines fallback commands for that MIME type that will only be used if no non-fallback entry can be found. For example, an entry of the form text/*; ; x-java-fallback-entry=true; x-java-view=com.sun.TextViewer specifies a view command to be used for any text MIME type. This view command would only be used if a non-fallback view command for the MIME type could not be found.

MailcapCommandMap aware mailcap files have the following general form:

# Comments begin with a '#' and continue to the end of the line.
<mime type>; ; <parameter list>
# Where a parameter list consists of one or more parameters,
# where parameters look like: x-java-view=com.sun.TextViewer
# and a parameter list looks like:
text/plain; ; x-java-view=com.sun.TextViewer; x-java-edit=com.sun.TextEdit
# Note that mailcap entries that do not contain 'x-java' parameters
# and comply to RFC 1524 are simply ignored:
image/gif; /usr/dt/bin/sdtimage %s

Author:
Bart Calder, Bill Shannon

Constructor Summary
MailcapCommandMap()
          The default Constructor.
MailcapCommandMap(InputStream is)
          Constructor that allows the caller to specify an InputStream containing a mailcap file.
MailcapCommandMap(String fileName)
          Constructor that allows the caller to specify the path of a mailcap file.
 
Method Summary
 void addMailcap(String mail_cap)
          Add entries to the registry.
 DataContentHandler createDataContentHandler(String mimeType)
          Return the DataContentHandler for the specified MIME type.
 CommandInfo[] getAllCommands(String mimeType)
          Get all the available commands in all mailcap files known to this instance of MailcapCommandMap for this MIME type.
 CommandInfo getCommand(String mimeType, String cmdName)
          Get the command corresponding to cmdName for the MIME type.
 String[] getMimeTypes()
          Get all the MIME types known to this command map.
 String[] getNativeCommands(String mimeType)
          Get the native commands for the given MIME type.
 CommandInfo[] getPreferredCommands(String mimeType)
          Get the preferred command list for a MIME Type.
 
Methods inherited from class javax.activation.CommandMap
createDataContentHandler, getAllCommands, getCommand, getDefaultCommandMap, getPreferredCommands, setDefaultCommandMap
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

MailcapCommandMap

public MailcapCommandMap()
The default Constructor.

MailcapCommandMap

public MailcapCommandMap(String fileName)
                  throws IOException
Constructor that allows the caller to specify the path of a mailcap file.

Parameters:
fileName - The name of the mailcap file to open
Throws:
IOException - if the file can't be accessed

MailcapCommandMap

public MailcapCommandMap(InputStream is)
Constructor that allows the caller to specify an InputStream containing a mailcap file.

Parameters:
is - InputStream of the mailcap file to open
Method Detail

getPreferredCommands

public CommandInfo[] getPreferredCommands(String mimeType)
Get the preferred command list for a MIME Type. The MailcapCommandMap searches the mailcap files as described above under Mailcap file search order.

The result of the search is a proper subset of available commands in all mailcap files known to this instance of MailcapCommandMap. The first entry for a particular command is considered the preferred command.

Specified by:
getPreferredCommands in class CommandMap
Parameters:
mimeType - the MIME type
Returns:
the CommandInfo objects representing the preferred commands.

getAllCommands

public CommandInfo[] getAllCommands(String mimeType)
Get all the available commands in all mailcap files known to this instance of MailcapCommandMap for this MIME type.

Specified by:
getAllCommands in class CommandMap
Parameters:
mimeType - the MIME type
Returns:
the CommandInfo objects representing all the commands.

getCommand

public CommandInfo getCommand(String mimeType,
                              String cmdName)
Get the command corresponding to cmdName for the MIME type.

Specified by:
getCommand in class CommandMap
Parameters:
mimeType - the MIME type
cmdName - the command name
Returns:
the CommandInfo object corresponding to the command.

addMailcap

public void addMailcap(String mail_cap)
Add entries to the registry. Programmatically added entries are searched before other entries.

The string that is passed in should be in mailcap format.

Parameters:
mail_cap - a correctly formatted mailcap string

createDataContentHandler

public DataContentHandler createDataContentHandler(String mimeType)
Return the DataContentHandler for the specified MIME type.

Specified by:
createDataContentHandler in class CommandMap
Parameters:
mimeType - the MIME type
Returns:
the DataContentHandler

getMimeTypes

public String[] getMimeTypes()
Get all the MIME types known to this command map.

Overrides:
getMimeTypes in class CommandMap
Returns:
array of MIME types as strings
Since:
JAF 1.1

getNativeCommands

public String[] getNativeCommands(String mimeType)
Get the native commands for the given MIME type. Returns an array of strings where each string is an entire mailcap file entry. The application will need to parse the entry to extract the actual command as well as any attributes it needs. See RFC 1524 for details of the mailcap entry syntax. Only mailcap entries that specify a view command for the specified MIME type are returned.

Returns:
array of native command entries
Since:
JAF 1.1
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