org.apache.wicket.markup.html.image.resource.BlobImageResource.java Source code

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Here is the source code for org.apache.wicket.markup.html.image.resource.BlobImageResource.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.markup.html.image.resource;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Blob;
import java.sql.SQLException;

import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.request.resource.DynamicImageResource;
import org.apache.wicket.util.io.Streams;

/**
 * An ImageResource subclass for dynamic images that come from database BLOB fields. Subclasses
 * override getBlob() to provide the image data to send back to the user. A given subclass may
 * decide how to produce this data and whether/how to buffer it.
 * 
 * @author Eelco Hillenius
 */
public abstract class BlobImageResource extends DynamicImageResource {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    /**
     * Construct.
     * 
     * @param format
     */
    public BlobImageResource(String format) {
        super(format);
    }

    /**
     * Construct.
     */
    public BlobImageResource() {
    }

    @Override
    protected byte[] getImageData(Attributes attributes) {
        try {
            Blob blob = getBlob(attributes);
            if (blob != null) {
                InputStream in = blob.getBinaryStream();
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                Streams.copy(in, out);
                return out.toByteArray();
            }
            return new byte[0];
        } catch (SQLException e) {
            throw new WicketRuntimeException("Error while reading image data", e);
        } catch (IOException e) {
            throw new WicketRuntimeException("Error while reading image data", e);
        }
    }

    /**
     * Gets the BLOB (Binary Large OBject) that holds the raw image data.
     *
     * @param attributes
     *      the current web attributes (request, response, parameters)
     * @return the BLOB
     */
    protected abstract Blob getBlob(Attributes attributes);
}