java.beans.PropertyChangeListener

 import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
 import java.beans.PropertyChangeSupport;

 public class DemoBeans {  

     private String demoName;
     private String Version;
     PropertyChangeSupport listeners = new PropertyChangeSupport(this);  

     public DemoBeans() {
         demoName = "initValue";
         Version="v1000";
     }  

     public String getDemoName() {
         return demoName;
     }  

     public void setDemoName(String demoName) {
         String oldValue = this.demoName;
         this.demoName = demoName;
         //发布监听事件
         firePropertyChange("demoName", oldValue, demoName);  

     }  

     public void setDemoVersion(String demoVersion) {
         String oldVersion = this.Version;
         this.Version = demoVersion;
         //发布监听事件
         firePropertyChange("demoVersion", oldVersion, demoVersion);  

     }
     public void addPropertyChangeListener(PropertyChangeListener listener) {
         listeners.addPropertyChangeListener(listener);
     }  

     public void removePropertyChangeListener(PropertyChangeListener listener){
         listeners.addPropertyChangeListener(listener);
     }  

     /**
      * 触发属性改变的事件
      */
     protected void firePropertyChange(String prop, Object oldValue, Object newValue) {
         listeners.firePropertyChange(prop, oldValue, newValue);
     }
     public static void main(String[] args) {
         DemoBeans beans = new DemoBeans();  

         beans.addPropertyChangeListener(
                 new PropertyChangeListener(){
             public void propertyChange(PropertyChangeEvent evt) {
                  if(evt.getPropertyName().equals("demoVersion")){
                      System.out.println("version_OldValue:"+evt.getOldValue());
                      System.out.println("version_NewValue:"+evt.getNewValue());
                      System.out.println("version_tPropertyName:"+evt.getPropertyName());
                  }
                  else
                  {
                      System.out.println("name_OldValue:"+evt.getOldValue());
                      System.out.println("name_NewValue:"+evt.getNewValue());
                      System.out.println("name_tPropertyName:"+evt.getPropertyName());
                  }

             }});  

         beans.setDemoName("test");
         beans.setDemoVersion("v2000");

     }
 }