jtcomposite.java

来自「Java Pattern Oriented Framework (Jt) 是为了」· Java 代码 · 共 357 行

package Jt;
import java.util.*;


/**
 * Jt Implementation of the Composite pattern.
 */

public class JtComposite extends JtPrototype {

  public static final String JtCLASS_NAME = JtComposite.class.getName(); 
  private static final long serialVersionUID = 1L;
  private  Hashtable hashtable = null;
  public static final String JtREMOVE_CHILD = "JtREMOVE_CHILD";
  public static final String JtADD_CHILD = "JtADD_CHILD";
  public static final String JtGET_CHILD = "JtGET_CHILD";
  public Iterator iterator;
  


  /**
    * Changes the hastable used to represent this class and store component objects.
    */ 

  public void setHashtable (Hashtable hashtable) {
    this.hashtable = hashtable;
  }


  /**
    * Returns the hastable used to represent this class and store component objects.
    */ 

  public Hashtable getHashtable () {
    return (hashtable);
  }
  
  public Iterator getIterator () {
      Collection col;

      if (hashtable == null)
          return null;

      col = hashtable.values();

      if (col == null)
          return null;

      return (col.iterator());

  }
  
  public void setIterator () {
 

  }

  public JtComposite () {
  }



  // Broadcast a message

  private void broadcastMessage (JtMessage msg)
  {
      Collection values;
      Iterator it;
      Object obj;
      JtMessage msg1;
      
      if (msg == null || hashtable == null)
          return;

      values = hashtable.values ();
      if (values == null)
          return;

      synchronized (hashtable) {
          it = values.iterator ();

          while (it.hasNext()) {
              obj = it.next ();  
              if (!(obj instanceof JtInterface))
                  continue;
              if (!(obj instanceof JtComposite)) {
                  sendMessage (obj, msg);
                  continue;
              }    
              msg1 = new JtMessage (JtObject.JtREMOVE);
              msg1.setMsgContent(msg);
              sendMessage (obj, msg1); 
          }
      }

  }


  /**
    * Process object messages.
    * <ul>
    * <li> JtADD_CHILD - Adds the object specified by msgContent to this composition. 
    * If the object is an instance JtObject, it is stored using the object name (objName) as the key.
    * Otherwise obj.toString () is used as the key.
    * <li> JtREMOVE_CHILD - Removes an object from this composition. msgContent specifies
    * the key needed to remove the object.
    * <li> JtGET_CHILD - Returns the object specified by msgContent (key) or null if it
    * doesn't exist. 
    * <li> JtBROADCAST - Broadcast the message specified by msgContent to all the objects
    * in this composition.
    * <li>JtREMOVE - Broadcast JtREMOVE to all the objects in this composition.
    * </ul>
    * @param message Jt Message
    */

  public Object processMessage (Object message) {

   String msgid = null;
   JtMessage e = (JtMessage) message;
   Object content;
   //Object data;


     if (e == null)
	return null;

     msgid = (String) e.getMsgId ();

     if (msgid == null)
	return null;

     content = e.getMsgContent();
     //data = e.getMsgData ();

     // Remove the composite
     if (msgid.equals (JtObject.JtREMOVE)) {
       // send JtREMOVE to all the members of the composite  
       broadcastMessage (new JtMessage (JtObject.JtREMOVE));  
       return (null);     
     }

     if (msgid.equals (JtComposite.JtADD_CHILD)) {
        // Add an object to the hash table

        if (content == null) {
          handleWarning 
            ("JtComposite.processMessage(JtADD_CHILD):invalid value (null)");
          return (null);

        }
        if (hashtable == null)

          hashtable = new Hashtable ();
        
        hashtable.put (content.toString(), content);        
        return (null);
     }     


     if (msgid.equals (JtComposite.JtREMOVE_CHILD)) {
        // Add an object to the hash table

        if (content == null) {
             handleWarning 
               ("JtComposite.processMessage(JtREMOVE_CHILD):invalid value (null)");
             return (null);

        }
        if (hashtable == null)
          hashtable = new Hashtable ();
        
        if (content instanceof String)
            return (hashtable.remove (content));  
        else
            return (hashtable.remove (content.toString()));   

     }   

     if (msgid.equals (JtComposite.JtGET_CHILD)) {


        if (content == null) {
          handleWarning 
            ("JtComposite.processMessage(JtGET):invalid value (null)");
          return (null);

        }
        if (hashtable == null)
          return (null);
        
        if (content instanceof String)
            return (hashtable.get (content));  
        else
            return (hashtable.get (content.toString()));        

     }  


     if (msgid.equals (JtObject.JtTEST)) {     
       return (test ());
     }

     // Broadcast a message to all the members
     // of the hash table

     if (msgid.equals (JtObject.JtBROADCAST)) {
     
       if (hashtable == null) {
         return (null);
       }

       broadcastMessage ((JtMessage) content);

       return (null);
     }

  
     return (super.processMessage (message));
     

  }

 /**
   * Unit tests the messages processed by JtComposite and illustrates the use of this class.
   */

  private Object test() {

    JtObject main = new JtFactory ();
    JtMessage msg;
    JtEcho echo1;
    JtEcho echo2;



    echo1 = (JtEcho) createObject (JtEcho.JtCLASS_NAME, "echo1");
    echo2 = (JtEcho) createObject (JtEcho.JtCLASS_NAME, "echo2");

    System.out.println ("JtComposite(JtADD_CHILD): adding a child ...");

    msg = new JtMessage (JtComposite.JtADD_CHILD);

    setValue (msg, "msgContent", echo1);

    sendMessage (this, msg);

    System.out.println ("JtComposite(JtADD_CHILD): adding a child ...");

    msg = new JtMessage (JtComposite.JtADD_CHILD);

    setValue (msg, "msgContent", echo2);


    sendMessage (this, msg);


    msg = new JtMessage (JtComposite.JtGET_CHILD);
    main.setValue (msg, "msgContent", "echo1");

    System.err.println ("JtComposite(JtGET_CHILD):" + 
      sendMessage (this, msg));

    System.out.println ("Printing the composition (XML format) ...");

    sendMessage (this, new JtMessage (JtComposite.JtPRINT));


    msg = new JtMessage (JtComposite.JtREMOVE_CHILD);

    main.setValue (msg, "msgContent", "echo1");

    System.err.println ("JtComposite(JtREMOVE_CHILD):" + 
      sendMessage (this, msg));


    msg = new JtMessage (JtObject.JtBROADCAST);
    msg.setMsgContent (new JtMessage (JtObject.JtPRINT));

    System.out.println 
    ("JtComposite(JtBROADCAST): broadcasting a message to the composition ...");

    sendMessage (this, msg);


    return (this);


  }
 
  /**
   * Demonstrates the messages processed by JtComposite
   */

  public static void main(String[] args) {

    JtObject factory = new JtFactory ();
    JtComposite composite, composite1;
    Double leaf1 = new Double (1.0);
    Double leaf2 = new Double (2.0);
    Double leaf3 = new Double (3.0);  
    
    JtMessage msg;
  
    
    // Create an instance of JtComposite

    composite = (JtComposite) factory.createObject (JtComposite.JtCLASS_NAME, "composite");
    
    
    // Add objects to the composite
        
    msg = new JtMessage (JtComposite.JtADD_CHILD);
    msg.setMsgContent(leaf1); 
    
    factory.sendMessage(composite, msg);   
    msg.setMsgContent(leaf2);
    factory.sendMessage(composite, msg);
        
    composite1 = (JtComposite) factory.createObject (JtComposite.JtCLASS_NAME, "composite1");    
    msg.setMsgContent(leaf3);

    factory.sendMessage(composite1, msg);
    
    msg = new JtMessage (JtComposite.JtADD_CHILD);
    msg.setMsgContent(composite1);
    factory.sendMessage(composite, msg);
    
    // Print the composite (XML format)
    
    factory.sendMessage(composite, new JtMessage (JtObject.JtPRINT));
    
    // Manipulate the composite
    
    msg = new JtMessage (JtComposite.JtGET_CHILD);
    msg.setMsgContent(leaf1.toString());
    System.out.println ("leaf1 = " + factory.sendMessage(composite, msg));
    
    msg = new JtMessage (JtComposite.JtREMOVE_CHILD);
    msg.setMsgContent(leaf2.toString());
    factory.sendMessage(composite, msg); 
    
    // Print the composite (XML format)
    
    factory.sendMessage(composite, new JtMessage (JtObject.JtPRINT));
     
    factory.sendMessage (composite, new JtMessage (JtObject.JtTEST));
    factory.removeObject ("composite");


  }

}