Jface中的属性改变事件观察者模式

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Jface中的属性改变事件观察者模式

1.模式涉及的类

org.eclipse.jface.util.IPropertyChangeListener; （接口）
org.eclipse.jface.util.PropertyChangeEvent;（类）

2.类图

在这里插入图片描述

3.使用方式

3.1.定义一个管理器

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.定义事件生产者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.定义事件生产者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.定义事件消费者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);}@Overridepublic void propertyChange(PropertyChangeEvent event) {// TODO Auto-generated method stubSystem.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.定义事件消费者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);}@Overridepublic void propertyChange(PropertyChangeEvent event) {// TODO Auto-generated method stubSystem.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.测试例程

public class Test {public static void main(String[] args) {// TODO Auto-generated method stubMyPropertyOberverA 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.运行结果

-----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