org.apache.wicket.ajax.AjaxChannel.java Source code

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Here is the source code for org.apache.wicket.ajax.AjaxChannel.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.wicket.ajax;

import org.apache.wicket.util.io.IClusterable;
import org.apache.wicket.util.lang.Args;

/**
 * A Channel used to define how Ajax requests are processed at the client side.
 * 
 * Channels are either:
 * <ul>
 * <li>queueing - Ajax requests are kept in a Queue at the client side and processed one at a time.
 * Default.</li>
 * <li>dropping - only the last Ajax request is processed, all previously scheduled requests are discarded</li>
 * <li>active - discards any Ajax requests if there is a running Ajax request on the same channel</li>
 * </ul>
 * 
 * @author Martin Dilger
 */
public class AjaxChannel implements IClusterable {
    private static final long serialVersionUID = 1L;

    /**
     * The type of an {@link AjaxChannel}
     */
    public static enum Type {

        /**
         * Ajax requests are kept in a Queue at the client side and processed one at a time
         */
        QUEUE,

        /**
         * dropping - only the last Ajax request is processed, the others are discarded
         */
        DROP,

        /**
         * the ajax call will discarded if there is an active/running request on the same channel
         */
        ACTIVE
    }

    /**
     * The name of the default channel
     */
    public static final String DEFAULT_NAME = "0";

    /**
     * The type of the default channel
     */
    public static final Type DEFAULT_TYPE = Type.QUEUE;

    /**
     * The default channel for all Ajax calls
     */
    public static final AjaxChannel DEFAULT = new AjaxChannel(DEFAULT_NAME, DEFAULT_TYPE);

    private final String name;

    private final Type type;

    /**
     * Construct.
     * 
     * @param name
     *            the name of the channel
     */
    public AjaxChannel(final String name) {
        this(name, Type.QUEUE);
    }

    /**
     * Construct.
     * 
     * @param name
     *            the name of the channel
     * @param type
     *            the behavior type of this channel
     */
    public AjaxChannel(final String name, final Type type) {
        this.name = Args.notNull(name, "name");
        this.type = Args.notNull(type, "type");
    }

    /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @return the type of this channel
     * @see AjaxChannel.Type
     */
    public Type getType() {
        return type;
    }

    /**
     * Calculates the ChannelName.
     * 
     * @return a String in the format channelName|d for DropChannels, channelName|s for Stackable
     *         Channels.
     */
    String getChannelName() {
        return toString();
    }

    @Override
    public String toString() {
        return String.format("%s|%s", name, getShortType(type));
    }

    private String getShortType(Type t) {
        String shortType;
        switch (t) {
        case DROP:
            shortType = "d";
            break;
        case ACTIVE:
            shortType = "a";
            break;
        case QUEUE:
        default:
            // 's' comes from 'stack', but it really acts as a queue.
            shortType = "s";
        }
        return shortType;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;

        AjaxChannel that = (AjaxChannel) o;

        if (!name.equals(that.name))
            return false;
        if (type != that.type)
            return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result = name.hashCode();
        result = 31 * result + type.hashCode();
        return result;
    }
}