Module java.activation

Package javax.activation

Class CommandInfo

java.lang.Object

javax.activation.CommandInfo

public class CommandInfo
extends Object

The CommandInfo class is used by CommandMap implementations to describe the results of command requests. It provides the requestor with both the verb requested, as well as an instance of the bean. There is also a method that will return the name of the class that implements the command but it is not guaranteed to return a valid value. The reason for this is to allow CommandMap implmentations that subclass CommandInfo to provide special behavior. For example a CommandMap could dynamically generate JavaBeans. In this case, it might not be possible to create an object with all the correct state information solely from the class name.

Since:

1.6

Constructor Summary

Constructors

Constructor	Description
CommandInfo(String verb, String className)	The Constructor for CommandInfo.

Method Summary

Modifier and Type	Method	Description
String	getCommandClass()	Return the command's class name.
String	getCommandName()	Return the command verb.
Object	getCommandObject(DataHandler dh, ClassLoader loader)	Return the instantiated JavaBean component.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CommandInfo

public CommandInfo(String verb,
                   String className)

The Constructor for CommandInfo.

Parameters:

verb - The command verb this CommandInfo decribes.

className - The command's fully qualified class name.

Method Detail

getCommandName

public String getCommandName()

Return the command verb.

Returns:

the command verb.

getCommandClass

public String getCommandClass()

Return the command's class name. This method MAY return null in cases where a CommandMap subclassed CommandInfo for its own purposes. In other words, it might not be possible to create the correct state in the command by merely knowing its class name. DO NOT DEPEND ON THIS METHOD RETURNING A VALID VALUE!

Returns:

The class name of the command, or null

getCommandObject

public Object getCommandObject(DataHandler dh,
                               ClassLoader loader)
                        throws IOException,
                               ClassNotFoundException

Return the instantiated JavaBean component.

If java.beans.Beans is visible then it's java.beans.Beans#instantiate method is invoked to instantiate the component as a JavaBeans component. When java.beans.Beans is not visible (when java.desktop module is not readable or when the runtime image does not contain the java.desktop module) then the command's class is loaded and instantiated with its public no-args constructor.

The component class needs to be public.

If the bean implements the javax.activation.CommandObject interface, call its setCommandContext method.

If the DataHandler parameter is null, then the bean is instantiated with no data. NOTE: this may be useful if for some reason the DataHandler that is passed in throws IOExceptions when this method attempts to access its InputStream. It will allow the caller to retrieve a reference to the bean if it can be instantiated.

If the bean does NOT implement the CommandObject interface, this method will check if it implements the java.io.Externalizable interface. If it does, the bean's readExternal method will be called if an InputStream can be acquired from the DataHandler.

Parameters:

dh - The DataHandler that describes the data to be passed to the command.

loader - The ClassLoader to be used to instantiate the bean.

Returns:

The bean

Throws:

IOException - for failures reading data

ClassNotFoundException - if command object class can't be found

See Also:

Beans.instantiate(java.lang.ClassLoader, java.lang.String), CommandObject