Modo de observador de eventos de cambio de propiedad en Jface
1. Las clases involucradas en el patrón
org.eclipse.jface.util.IPropertyChangeListener; (interfaz)
org.eclipse.jface.util.PropertyChangeEvent; (clase)
2. Diagrama de clases
3. Cómo utilizar
3.1. Definir un gerente
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
public class ValuePropertChangeManager {
private static ValuePropertChangeManager INSTANCE;
private static final Map<String, IPropertyChangeListener> map = new HashMap<String, IPropertyChangeListener>();
private ValuePropertChangeManager(){
}
public static ValuePropertChangeManager getInstance() {
if(INSTANCE==null)
INSTANCE = new ValuePropertChangeManager();
return INSTANCE;
}
// 触发属性改变监听事件
public void firePropertyChangeListener(PropertyChangeEvent event) {
final Iterator iter = map.keySet().iterator();
while (iter.hasNext()) {
map.get(iter.next()).propertyChange(event);
}
}
// 注册属性改变监听器
public void addPropertyChangeListener(final String listenerID,
final IPropertyChangeListener listener) {
if (!map.containsKey(listenerID))
map.put(listenerID, listener);
}
// 注销属性改变监听器
public void removePropertyChangeListener(final String listenerID) {
if (map.containsKey(listenerID))
map.remove(listenerID);
}
}
3.2. Definir productor de eventos A
import org.eclipse.jface.util.PropertyChangeEvent;
public class MyPropertyProviderA {
private String myValue;
public void setValue(String curValue){
String oldValue = myValue;
myValue = curValue;
ValuePropertChangeManager.getInstance()
.firePropertyChangeListener(new PropertyChangeEvent(this, "myValue", oldValue, myValue));
}
}
3.3. Definir productor de eventos B
import org.eclipse.jface.util.PropertyChangeEvent;
public class MyPropertyProviderB {
private String myValue;
public void setValue(String curValue){
String oldValue = myValue;
myValue = curValue;
ValuePropertChangeManager.getInstance()
.firePropertyChangeListener(new PropertyChangeEvent(this, "myValue", oldValue, myValue));
}
}
3.4. Definir el consumidor de eventos A
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
public class MyPropertyOberverA implements IPropertyChangeListener{
public void registerMyValueChange(){
ValuePropertChangeManager.getInstance()
.addPropertyChangeListener("MyPropertyOberverA", this);
}
@Override
public void propertyChange(PropertyChangeEvent event) {
// TODO Auto-generated method stub
System.out.println("-----MyPropertyOberverA do for propertyChange-----");
System.out.println("source class="+event.getSource().getClass());
System.out.println("Property="+event.getProperty());
System.out.println("old value="+event.getOldValue());
System.out.println("new value="+event.getNewValue());
}
}
3.5. Definir el consumidor de eventos B
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
public class MyPropertyOberverB implements IPropertyChangeListener{
public void registerMyValueChange(){
ValuePropertChangeManager.getInstance()
.addPropertyChangeListener("MyPropertyOberverB", this);
}
@Override
public void propertyChange(PropertyChangeEvent event) {
// TODO Auto-generated method stub
System.out.println("-----MyPropertyOberverB do for propertyChange-----");
System.out.println("source class="+event.getSource().getClass());
System.out.println("Property="+event.getProperty());
System.out.println("old value="+event.getOldValue());
System.out.println("new value="+event.getNewValue());
}
}
3.6. Rutina de prueba
public class Test {
public static void main(String[] args) {
// TODO Auto-generated method stub
MyPropertyOberverA poa = new MyPropertyOberverA();
poa.registerMyValueChange();
MyPropertyOberverB pob = new MyPropertyOberverB();
pob.registerMyValueChange();
MyPropertyProviderA ppa = new MyPropertyProviderA();
ppa.setValue("value 1");
MyPropertyProviderB ppb = new MyPropertyProviderB();
ppb.setValue("value 0.618");
}
}
3.7. Resultados en ejecución
-----MyPropertyOberverB do for propertyChange-----
source class=class com.tyde.jfcs.ui.test.MyPropertyProviderA
Property=myValue
old value=null
new value=value 1
-----MyPropertyOberverA do for propertyChange-----
source class=class com.tyde.jfcs.ui.test.MyPropertyProviderA
Property=myValue
old value=null
new value=value 1
-----MyPropertyOberverB do for propertyChange-----
source class=class com.tyde.jfcs.ui.test.MyPropertyProviderB
Property=myValue
old value=null
new value=value 0.618
-----MyPropertyOberverA do for propertyChange-----
source class=class com.tyde.jfcs.ui.test.MyPropertyProviderB
Property=myValue
old value=null
new value=value 0.618
4. Descripción
En comparación con los métodos Sujeto y Observador del modo de observador jdk,
(1) Admite múltiples desencadenantes de eventos;
(2) Admite situaciones en las que es imposible o inconveniente establecer la relación entre observadores y generadores de eventos en el mismo lugar;