cc.twittertools.corpus.data.JsonStatusBlockReader.java Source code

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Here is the source code for cc.twittertools.corpus.data.JsonStatusBlockReader.java

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/**
 * Twitter Tools
 *
 * 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 cc.twittertools.corpus.data;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.zip.GZIPInputStream;

import com.google.common.base.Preconditions;
import twitter4j.Status;
import twitter4j.TwitterException;
import twitter4j.TwitterObjectFactory;

/**
 * Abstraction for an stream of statuses, backed by an underlying gzipped file with JSON-encoded
 * tweets, one per line.
 */
public class JsonStatusBlockReader implements StatusStream {
    private final BufferedReader br;

    public JsonStatusBlockReader(File file) throws IOException {
        Preconditions.checkNotNull(file);

        if (!file.getName().endsWith(".gz")) {
            throw new IOException("Expecting .gz compressed file!");
        }

        br = new BufferedReader(new InputStreamReader(new GZIPInputStream(new FileInputStream(file)), "UTF-8"));
    }

    /**
     * Returns the next status, or <code>null</code> if no more statuses.
     */
    public Status next() throws IOException {
        Status nxt = null;

        while (nxt == null) {
            String raw = br.readLine();

            // Check to see if we've reached end of file.
            if (raw == null) {
                return null;
            }

            try {
                nxt = TwitterObjectFactory.createStatus(raw);
            } catch (TwitterException e) {
            }
        }
        return nxt;
    }

    public void close() throws IOException {
        br.close();
    }
}