详解java中的PropertyChangeSupport与PropertyChangeListener

package com.wang.test.property;  import java.beans.PropertyChangeListener; import java.beans.PropertyChangeSupport;  public class TestBean {    protected final PropertyChangeSupport support = new PropertyChangeSupport(this);      private String str;      public String getStr() {     return str;   }    public void setStr(String str) {     support.firePropertyChange("str", this.str, str);     this.str = str;   }      public void addPropertyChangeListener(PropertyChangeListener listener) {     support.addPropertyChangeListener(listener);   }      public void removePropertyChangeListener(PropertyChangeListener listener) {     support.removePropertyChangeListener(listener);   } } 

package com.wang.test.property;  import java.beans.PropertyChangeEvent; import java.beans.PropertyChangeListener;  public class PropertyChangeSupportTest {    public static void main(String[] args) {           TestBean test = new TestBean();     test.setStr("ddddd");     test.addPropertyChangeListener(new PropertyChangeListener1());     test.setStr("yyyy");          //test.addPropertyChangeListener(new PropertyChangeListener2());     //test.setStr("hhhhhhf");   }        public static class PropertyChangeListener1 implements PropertyChangeListener{      @Override     public void propertyChange(PropertyChangeEvent evt) {       System.out.println( "1: " + evt.getPropertyName() + "  " + evt.getNewValue() + "  " + evt.getOldValue());            }   }      public static class PropertyChangeListener2 implements PropertyChangeListener{      @Override     public void propertyChange(PropertyChangeEvent evt) {       System.out.println( "2: " + evt.getPropertyName() + "  " + evt.getNewValue() + "  " + evt.getOldValue());            }   } }