machinecomponent.java

java设计模式源码

package com.oozinoz.machine;

/*
 * Copyright (c) 2001, 2005. Steven J. Metsker.
 * 
 * Steve Metsker makes no representations or warranties about
 * the fitness of this software for any particular purpose, 
 * including the implied warranty of merchantability.
 *
 * Please use this software as you wish with the sole
 * restriction that you may not claim that you wrote it.
 */

import java.util.*;
import com.oozinoz.iterator.ComponentIterator;

/**
 * Objects of this class represent either individual machines or composites of
 * machines.
 * 
 * @author Steven J. Metsker
 *  
 */
public abstract class MachineComponent {
    protected int id = 0;
    protected String name;
    protected MachineComponent parent;
    protected Engineer responsible;

    /**
     * Create a machine component with the given id.
     * @param id this machine's identity
     */
    protected MachineComponent(int id) {
        this(id, null);
    }

    /**
     * Create a machine component with the given id and parent
     * @param id this machine's identity
     * @param parent the machine composite that this component belongs to
     */
    protected MachineComponent(int id, MachineComponent parent) {
        this(id, parent, null);
    }

    /**
     * Create a machine component with the given id and parent
     * @param id this machine's identity
     * @param parent the machine composite that this component belongs to
     */
    protected MachineComponent(int id, MachineComponent parent, Engineer responsible) {
        this.id = id;
        this.parent = parent;
        this.responsible = responsible;
    }

  /**
     * @param visitor a visitor that will add some sort of behavior
     */
    public abstract void accept(MachineVisitor visitor);

    /**
     * @return the number of leaf node machines in this composite.
     */
    public abstract int getMachineCount();

    /*
     * Subclasses implement this to support the isTree() algorithm.
     */
    protected abstract boolean isTree(Set s);

    /**
     * @return true if this component is atop an acyclic graph in which no node
     *         has two parents (two references to it).
     */
    public boolean isTree() {
        return isTree(new HashSet());
    }

    /**
     * @return an iterator for this component
     */
    public ComponentIterator iterator() {
        return iterator(new HashSet());
    }
    
    public abstract ComponentIterator iterator(Set set);

    /**
     * @return a textual representation of this component
     */
    public String toString() {
        if (name != null) {
            return name;
        }
        String s = getClass().getName();
        return s.substring(s.lastIndexOf('.') + 1) + ":" + id;
    }

    /**
     * @return true if, according to business rules, this component and the
     *         supplied object refer to the same thing.
     */
    public boolean equals(Object o) {
        if (o == this)
            return true;
        if (!(o instanceof MachineComponent))
            return false;
        MachineComponent mc = (MachineComponent) o;
        return id == mc.id;
    }

    /**
     * @return the engineer who is responsible for this machine
     */
    public Engineer getResponsible() {
        if (responsible != null)
            return responsible;
        
        if (parent != null)
            return parent.getResponsible();

        return null;
    }

    /**
     * @return this component's id
     */
    public int getId() {
        return id;
    }

    /**
     * @return this component's name
     */
    public String getName() {
        return name;
    }

    /**
     * @param name this component's name
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * @return the composite that this machine belongs to.
     */
    public MachineComponent getParent() {
        return parent;
    }

    /**
     * @param id the machine id to search for
     * @return a machine within this machine graph, given its ID.
     */
    public MachineComponent find(int thatId) {
        if (id == thatId)
            return this;
        return null;
    }

    /**
     * @param id the machine name to search for
     * @return a machine with the given name.
     */
    public MachineComponent find(String name) {
        if (this.toString().equals(name))
            return this;
        return null;
    }
}