org.wicketstuff.minis.util.FutureModel.java Source code

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Here is the source code for org.wicketstuff.minis.util.FutureModel.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.wicketstuff.minis.util;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.model.AbstractReadOnlyModel;

/**
 * A read-only model implementation that retrieves the model object from a {@link Future} object.
 * This is useful when retrieving data from slow back-ends asynchronously before the synchronous
 * rendering of the Wicket components happens.
 * 
 * @author <a href="http://sebthom.de/">Sebastian Thomschke</a>
 */
public class FutureModel<T> extends AbstractReadOnlyModel<T> {
    private static final long serialVersionUID = 1L;

    private transient Future<T> future;
    private T futureValue = null;

    public FutureModel(final Future<T> future) {
        this.future = future;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void detach() {
        try {
            if (futureValue == null && future != null)
                futureValue = future.get();
        } catch (final InterruptedException ex) {
            throw new WicketRuntimeException(ex);
        } catch (final ExecutionException ex) {
            throw new WicketRuntimeException(ex);
        }
        future = null;
        super.detach();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public T getObject() {
        try {
            if (futureValue == null && future != null)
                futureValue = future.get();
        } catch (final InterruptedException ex) {
            throw new WicketRuntimeException(ex);
        } catch (final ExecutionException ex) {
            throw new WicketRuntimeException(ex);
        }
        return futureValue;
    }
}