bindingmanager.java

eclipse开发笔记

package rcpdev.common.ui.databinding;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Vector;

import org.apache.commons.jxpath.JXPathContext;
import org.eclipse.core.runtime.IAdaptable;

import rcpdev.common.core.utils.MiscUtils;

public class BindingManager implements PropertyChangeListener {

	private IAdaptable bean;

	private HashMap<String, Vector<IBinding>> bindingMap;

	private PropertyChangeSupport delegate;

	public BindingManager(IAdaptable bean) {
		this.bean = bean;
		delegate = new PropertyChangeSupport(this);
		PropertyChangeSupport pcs = null;
		if ((pcs = (PropertyChangeSupport) bean
				.getAdapter(PropertyChangeSupport.class)) != null) {
			pcs.addPropertyChangeListener(this);
		}
		bindingMap = new HashMap<String, Vector<IBinding>>();
	}

	public void setBean(IAdaptable bean) {
		PropertyChangeSupport pcs = null;
		if ((pcs = (PropertyChangeSupport) this.bean
				.getAdapter(PropertyChangeSupport.class)) != null) {
			pcs.removePropertyChangeListener(this);
		}
		this.bean = bean;
		if(bean == null)
			return;
		if ((pcs = (PropertyChangeSupport) bean
				.getAdapter(PropertyChangeSupport.class)) != null) {
			pcs.addPropertyChangeListener(this);
		}
		loadAll();
	}

	public void addBinding(IBinding binding) {
		binding.addPropertyChangeListener(this);
		if (bindingMap.get(binding.getAttribute()) == null)
			bindingMap.put(binding.getAttribute(), new Vector<IBinding>());
		bindingMap.get(binding.getAttribute()).add(binding);
	}

	public IAdaptable getBean() {
		return bean;
	}

	public void propertyChange(PropertyChangeEvent evt) {
		/*
		 * When the value of control changed, use JXPath API to set
		 * corresponding value to the bean.
		 */
		if (IBinding.BINDING_VAL.equals(evt.getPropertyName())) {
			IBinding binding = (IBinding) evt.getSource();
			String attr = binding.getAttribute();
			Object value = evt.getNewValue();
			saveToBean(attr, value);
			return;
		}
		/*
		 * Value of the bean changed. Load value then set to corresponding
		 * controls.
		 */
		if (evt.getSource().equals(bean)) {
			Vector<IBinding> bindingList = bindingMap
					.get(evt.getPropertyName());
			if (bindingList == null)
				return;
			for (Iterator bi = bindingList.iterator(); bi.hasNext();) {
				IBinding binding = (IBinding) bi.next();
				if (!MiscUtils.equals(binding.getValue(), evt.getNewValue()))
					binding.setValue(evt.getNewValue());
			}
		}
	}

	protected Object loadFromBean(String attribute) {
		JXPathContext context = JXPathContext.newContext(bean);
		return context.getValue(attribute);
	}

	protected void saveToBean(String attribute, Object value) {
		JXPathContext context = JXPathContext.newContext(bean);
		Object oldVal = context.getValue(attribute);
		if (value != oldVal || (value != null && !value.equals(oldVal))) {
			// ((PropertyChangeSupport) bean
			// .getAdapter(PropertyChangeSupport.class))
			// .removePropertyChangeListener(this);
			context.setValue(attribute, value);
			// ((PropertyChangeSupport) bean
			// .getAdapter(PropertyChangeSupport.class))
			// .addPropertyChangeListener(this);
		}
	}

	/**
	 * Load all attribtues from bean to ui.
	 * 
	 */
	public void loadAll() {
		for (Iterator ite = bindingMap.entrySet().iterator(); ite.hasNext();) {
			Vector<IBinding> bindings = (Vector<IBinding>) ((Map.Entry) ite
					.next()).getValue();
			for (Iterator bi = bindings.iterator(); bi.hasNext();) {
				IBinding binding = (IBinding) bi.next();
				binding.setValue(loadFromBean(binding.getAttribute()));
			}
		}
	}

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

	public void firePropertyChange(PropertyChangeEvent evt) {
		delegate.firePropertyChange(evt);
	}

	public void removePropertyChangeListener(PropertyChangeListener listener) {
		delegate.removePropertyChangeListener(listener);
	}

}