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

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Here is the source code for com.google.walkaround.wave.server.attachment.AttachmentMetadataHandler.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.common.base.Optional;
import com.google.common.collect.ImmutableList;
import com.google.common.net.UriEscapers;
import com.google.inject.Inject;
import com.google.walkaround.util.server.servlet.AbstractHandler;
import com.google.walkaround.wave.server.servlet.ServletUtil;

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

import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Serves attachment metadata as JSON.
 *
 * We support POST because the client could legitimately ask for a very large
 * number of attachment ids at once, which may not fit into a GET request.
 *
 * At the same time, we should support GET because it is appropriate for small
 * requests and convenient for debugging.
 *
 * @author danilatos@google.com (Daniel Danilatos)
 */
public class AttachmentMetadataHandler extends AbstractHandler {
    /** Avoid doing too much work at once so the client can get incremental being loaded */
    private static final long MAX_REQUEST_TIME_MS = 4 * 1000;

    private static final String INVALID_ATTACHMENT_ID_METADATA_STRING = "{}";

    private final AttachmentService attachments;

    @Inject
    public AttachmentMetadataHandler(AttachmentService attachments) {
        this.attachments = attachments;
    }

    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        doRequest(req, resp);
    }

    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        doRequest(req, resp);
    }

    private List<AttachmentId> getIds(HttpServletRequest req) {
        ImmutableList.Builder<AttachmentId> out = ImmutableList.builder();
        for (String id : requireParameter(req, "ids").split(",", -1)) {
            out.add(new AttachmentId(id));
        }
        return out.build();
    }

    private void doRequest(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        Map<AttachmentId, Optional<AttachmentMetadata>> result = attachments.getMetadata(getIds(req),
                MAX_REQUEST_TIME_MS);
        JSONObject json = new JSONObject();
        try {
            for (Entry<AttachmentId, Optional<AttachmentMetadata>> entry : result.entrySet()) {
                JSONObject metadata = new JSONObject(
                        entry.getValue().isPresent() ? entry.getValue().get().getMetadataJsonString()
                                : INVALID_ATTACHMENT_ID_METADATA_STRING);
                String queryParams = "attachment="
                        + UriEscapers.uriQueryStringEscaper(false).escape(entry.getKey().getId());
                metadata.put("url", "/download?" + queryParams);
                metadata.put("thumbnailUrl", "/thumbnail?" + queryParams);
                json.put(entry.getKey().getId(), metadata);
            }
        } catch (JSONException e) {
            throw new Error(e);
        }
        ServletUtil.writeJsonResult(resp.getWriter(), json.toString());
    }
}