javax.activation: public class: CommandInfo

javax.activation
public class: CommandInfo [javadoc | source]

java.lang.Object
   javax.activation.CommandInfo

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:

Constructor:
public CommandInfo(String verb, String className) { this.verb = verb; this.className = className; } The Constructor for CommandInfo. Parameters: `verb` - The command verb this CommandInfo decribes. `className` - The command's fully qualified class name.

 public CommandInfo(String verb,
    String className) {
        this.verb = verb;
        this.className = className;
}

The Constructor for CommandInfo.

Parameters:

verb - The command verb this CommandInfo decribes.

className - The command's fully qualified class name.

Method from javax.activation.CommandInfo Summary:
getCommandClass, getCommandName, getCommandObject

Methods from java.lang.Object:
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from javax.activation.CommandInfo Detail:
public String getCommandClass() { return className; } 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!
public String getCommandName() { return verb; } Return the command verb.
public Object getCommandObject(DataHandler dh, ClassLoader loader) throws IOException, ClassNotFoundException { Object new_bean = null; // try to instantiate the bean new_bean = java.beans.Beans.instantiate(loader, className); // if we got one and it is a CommandObject if (new_bean != null) { if (new_bean instanceof CommandObject) { ((CommandObject)new_bean).setCommandContext(verb, dh); } else if (new_bean instanceof Externalizable) { if (dh != null) { InputStream is = dh.getInputStream(); if (is != null) { ((Externalizable)new_bean).readExternal( new ObjectInputStream(is)); } } } } return new_bean; } Return the instantiated JavaBean component. Begin by instantiating the component with `Beans.instantiate()`. 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.

Method from javax.activation.CommandInfo Detail:

 public String getCommandClass() {
        return className;
}

This method MAY return null in cases where a CommandMap subclassed CommandInfo for its own purposes.

DO NOT DEPEND ON THIS METHOD RETURNING A VALID VALUE!

 public String getCommandName() {
        return verb;
}

Return the command verb.

 public Object getCommandObject(DataHandler dh,
    ClassLoader loader) throws IOException, ClassNotFoundException {
        Object new_bean = null;
        // try to instantiate the bean
        new_bean = java.beans.Beans.instantiate(loader, className);
        // if we got one and it is a CommandObject
        if (new_bean != null) {
            if (new_bean instanceof CommandObject) {
                ((CommandObject)new_bean).setCommandContext(verb, dh);
            } else if (new_bean instanceof Externalizable) {
                if (dh != null) {
                    InputStream is = dh.getInputStream();
                    if (is != null) {
                        ((Externalizable)new_bean).readExternal(
                                               new ObjectInputStream(is));
                    }
                }
            }
        }
        return new_bean;
}

Begin by instantiating the component with Beans.instantiate().

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.