Field.java

/*******************************************************************************
 * Copyright 2015 xWic group (http://www.xwic.de)
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * 		http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and 
 * limitations under the License.
 *  
 *******************************************************************************/
package de.jwic.base;

import java.io.Serializable;
import java.util.Arrays;

import de.jwic.events.ValueChangedEvent;
import de.jwic.events.ValueChangedListener;
import de.jwic.util.StringTool;

/**
 * Represents a field on an HTML form that contains a string value or an array
 * of string values. A field is created for a control and is linked to it with
 * its name.<p> 
 * The field offers an ValueChangedEvent.
 * 
 * @author Florian Lippisch
 * @version $Revision: 1.2 $
 */
public class Field implements Serializable {

	private static final long serialVersionUID = 1L;
	
	private String name = null;
	private Control control = null;
	private String[] values = null;
	
	private ValueChangedListener[] listeners = null;
	
	/**
	 * Creates a new field with an autogenerated name.
	 * @param parent
	 */
	public Field (Control parent) {
		this(parent, null);
	}

	/**
	 * Creates a new field with the given name.
	 * @param parent
	 * @param name
	 */
	public Field (Control parent, String name) {
		this.control = parent;
		this.name = name;
		control.addField(this);
	}

	/**
	 * Removes the field from its container.
	 *
	 */
	public void destroy() {
		if (control != null) {
			control.removeField(this);
		}
	}
	
	/**
	 * Add a ValueChangedListener to this field.
	 * @param listener
	 */
	public synchronized void addValueChangedListener(ValueChangedListener listener) {
		if (listeners == null) {
			listeners = new ValueChangedListener[] { listener };
		} else {
			ValueChangedListener[] tmp = new ValueChangedListener[listeners.length + 1];
			System.arraycopy(listeners, 0, tmp, 0, listeners.length);
			tmp[listeners.length] = listener;
			listeners = tmp;
		}
	}
	
	/**
	 * Removes the specified listener from the field.
	 * @param listener
	 */
	public synchronized void removeValueChangedListener(ValueChangedListener listener) {
		if (listeners != null && listeners.length > 0) {
			ValueChangedListener[] tmp = new ValueChangedListener[listeners.length - 1];
			int idx = 0;
			for (int i = 0; i < listeners.length; i++) {
				if (listeners[i] != listener) {
					if (idx == tmp.length) {
						// the listener was not registerd
						return; // early exit
					}
					tmp[idx++] = listeners[i];
				}
			}
			listeners = tmp;
		}
	}
	
	/**
	 * Fires the value changed event.
	 * @param event
	 */
	protected void fireValueChangedEvent(ValueChangedEvent event) {
		if (listeners != null) {
			for (int i = 0; i < listeners.length; i++) { 
				listeners[i].valueChanged(event);
			}
		}
	}
	
	/**
	 * @return Returns the name.
	 */
	public String getName() {
		return name;
	}
	/**
	 * @param name The name to set.
	 */
	void setName(String name) {
		this.name = name;
	}
	
	/**
	 * Returns the id of the field. This property must return a unique id of
	 * the field that can be used to identify the field when it is submited
	 * by the browser.
	 * @return
	 */
	public String getId() {
		return "fld_" + control.getControlID() + "." + name;
	}
	
	
	/**
	 * Returns the values as a string. If the value is an array, the values
	 * are seperated by a semmicolon.
	 * @return
	 */
	public String getValue() {
		return StringTool.getSingleString(values);
	}

	/**
	 * Returns the values as array.
	 * @return Returns the values.
	 */
	public String[] getValues() {
		return values;
	}
	
	/**
	 * Set the value of the field.
	 * @param value
	 */
	public void setValue(String value) {
		setValues(new String[] { value });
	}
	
	/**
	 * Sets the values as array.
	 * @param values The values to set.
	 */
	public void setValues(String[] values) {
		if (!Arrays.equals(this.values, values)) {
			ValueChangedEvent event = new ValueChangedEvent(this, this.values, values);
			this.values = values;
			fireValueChangedEvent(event);
		}
	}

	/**
	 * Set the values of the field as array without fireing the ValueChangedEvent. The
	 * event is added to the ValueChangedQueue for later processing.
	 * @param values
	 * @param queue
	 */
	public void batchUpdate(String[] newValues, ValueChangedQueue queue) {
		if (!Arrays.equals(this.values, newValues)) {
			ValueChangedEvent event = new ValueChangedEvent(this, this.values, newValues);
			this.values = newValues;
			if (listeners != null) {
				queue.valueChanged(listeners, event);
			}
		}
	}
	
}