com.google.walkaround.wave.server.attachment.AttachmentMetadata.java Source code

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Here is the source code for com.google.walkaround.wave.server.attachment.AttachmentMetadata.java

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/*
 * Copyright 2011 Google Inc. All Rights Reserved.
 *
 * 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 com.google.walkaround.wave.server.attachment;

import com.google.appengine.api.blobstore.BlobKey;
import com.google.common.base.Preconditions;
import com.google.walkaround.util.shared.Assert;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.Serializable;

/**
 * Metadata associated with an attachment. Should not be changed for a given
 * attachment, so that it can be cached indefinitely.
 *
 * @author danilatos@google.com (Daniel Danilatos)
 */
// TODO(danilatos) Merge this with WalkaroundAttachment, once we have a json interface.
// Same goes for "ImageMetadata"
// TODO(danilatos) Consider using a proto-based implementation?
public class AttachmentMetadata implements Serializable {
    private static final long serialVersionUID = 562560590763783822L;

    public interface ImageMetadata {
        public int getWidth();

        public int getHeight();
    }

    private final AttachmentId id;
    private final BlobKey blobKey;
    // String for Serializable
    private final String rawMetadata;
    // Parsed version of rawMetadata.
    private transient JSONObject maybeMetadata;

    public AttachmentMetadata(AttachmentId id, BlobKey blobKey, JSONObject metadata) {
        this.id = Preconditions.checkNotNull(id, "null id");
        this.blobKey = Preconditions.checkNotNull(blobKey, "null blobKey");
        this.maybeMetadata = Preconditions.checkNotNull(metadata, "null metadata");
        this.rawMetadata = metadata.toString();
    }

    @Override
    public String toString() {
        return "AttachmentMetadata(" + id + ", " + blobKey + ", " + rawMetadata + ")";
    }

    public AttachmentId getId() {
        return id;
    }

    public BlobKey getBlobKey() {
        return blobKey;
    }

    private JSONObject getMetadata() {
        if (maybeMetadata == null) {
            Assert.check(rawMetadata != null, "rawMetadata is null");
            try {
                maybeMetadata = new JSONObject(rawMetadata);
            } catch (JSONException e) {
                throw new RuntimeException("Bad JSON: " + rawMetadata, e);
            }
        }
        return maybeMetadata;
    }

    public String getMetadataJsonString() {
        return rawMetadata;
    }

    public ImageMetadata getImage() {
        return createImageMetadata("image");
    }

    public ImageMetadata getThumbnail() {
        return createImageMetadata("thumbnail");
    }

    private ImageMetadata createImageMetadata(String key) {
        final JSONObject imgData;
        try {
            imgData = getMetadata().has(key) ? getMetadata().getJSONObject(key) : null;
        } catch (JSONException e) {
            throw new Error(e);
        }

        if (imgData == null) {
            return null;
        }

        return new ImageMetadata() {
            @Override
            public int getWidth() {
                try {
                    return imgData.getInt("width");
                } catch (JSONException e) {
                    throw new RuntimeException(e);
                }
            }

            @Override
            public int getHeight() {
                try {
                    return imgData.getInt("height");
                } catch (JSONException e) {
                    throw new RuntimeException(e);
                }
            }
        };
    }

}