command.java

一个对等计算发生器

/***************************************************************************
 *                                                                         *
 *                               Command.java                              *
 *                            -------------------                          *
 *   date                 : 16. Mai 2003, 18:30                            *
 *   copyright            : (C) 2004 Distributed and Mobile Systems Group  *
 *                              Lehrstuhl fuer Praktische Informatik       *
 *                              Universitaet Bamberg                       *
 *                              http://www.lspi.wiai.uni-bamberg.de/       *
 *   email                : [e-mail]              *
 *                                                                         *
 *                                                                         *
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   A copy of the license can be found in the license.txt file supplied   *
 *   with this software or at: http://www.gnu.org/copyleft/gpl.html        *
 *                                                                         *
 ***************************************************************************/

package de.uniba.wiai.lspi.util.console;

import java.util.*;
import java.io.PrintStream;

/**
 * @author   sven
 * @version 1.0.1
 */
public abstract class Command {
    
    /** 
     * The instances to execute the commands on. 
     */    
    protected Object[] toCommand;
    
    /**
	 * The parameters passed to this command are contained within this Hashtable.
	 * @uml.property   name="parameters"
	 * @uml.associationEnd   qualifier="key:java.lang.Object java.lang.String"
	 */    
    protected Map<String, String> parameters;
    
    /** 
     * Standard argument for displaying help of this command. 
     * If supplied all other parameters are ignored. 
     */    
    protected final String HELP_ARG1 = "help";
    
    /** 
     * Alternative standard argument for displaying help of this command. 
     * If supplied all other parameters are ignored. 
     */    
    protected final String HELP_ARG2 = "h";
    
    /** 
     * The PrintStream to print the command's output to. 
     */
    protected PrintStream out;
    
    /** 
     * Creates a new instance of Command.
     * @param out The java.io.PrintStream to that the command's output is printed.
     * @param toCommand The instance to execute the command on.
     */
    public Command(Object[] toCommand, PrintStream out) {
        this.toCommand = toCommand;
        this.out = out;
        this.parameters = new HashMap<String, String>();
    }
    
    /**
     * Set the <code>PrintStream</code>, to that this command prints its output.
     * @param out 
     *
     * @out The <code>PrintStream</code>. 
     */
    public void setPrintStream(PrintStream out){
        this.out = out; 
    }
    
    /** 
     * Add a command line parameter.
     * @param paramName The parameters name. Cannot contain spaces.
     * @param paramValue The parameters value. Cannot contain spaces.
     */    
    public final void addParameter(String paramName, String paramValue){
        this.parameters.put(paramName, paramValue);
    }
    
    /** 
     * Executes the command.
     * @throws ConsoleException Exception during execution of command.
     */    
    public final void execute() throws ConsoleException{
        if ( this.parameters.containsKey(this.HELP_ARG1) || this.parameters.containsKey(this.HELP_ARG2) ) {
            printOutHelp();
        }
        else {
            exec();
        }
    }
    
    /** 
     * To be overwritten by subclasses for command execution. The work of a 
     * command implementation is done in this method.
     * @throws ConsoleException Exception during execution.
     */    
    public abstract void exec() throws ConsoleException;
    
    /** 
     * To be overwritten. Display the help text of the Command. 
     */    
    public abstract void printOutHelp();
    
    /** Return the name of the command. Must not contain spaces.
     * To be overwritten by subclasses.
     * @return The commands name. For example: <CODE>exit</CODE>.
     */    
    public abstract String getCommandName();
    
    /**
	 * Set the parameters for the Command.
	 * @param parameters   Hashtable containing the parameter names as keys and the parameter values as values. Both represented as Strings.  Both must not contain spaces.
	 * @uml.property   name="parameters"
	 */    
    public void setParameters(Map<String, String> parameters) {
        this.parameters = parameters;
    }
    
}