azkaban.viewer.hdfs.TextFileViewer.java Source code

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Here is the source code for azkaban.viewer.hdfs.TextFileViewer.java

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/*
 * Copyright 2012 LinkedIn Corp.
 *
 * 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 azkaban.viewer.hdfs;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.EnumSet;
import java.util.Set;
import java.util.HashSet;

import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.permission.AccessControlException;
import org.apache.log4j.Logger;

public class TextFileViewer extends HdfsFileViewer {

    private static Logger logger = Logger.getLogger(TextFileViewer.class);
    private HashSet<String> acceptedSuffix = new HashSet<String>();

    private static final String VIEWER_NAME = "Text";

    public TextFileViewer() {
        acceptedSuffix.add(".txt");
        acceptedSuffix.add(".csv");
        acceptedSuffix.add(".props");
        acceptedSuffix.add(".xml");
        acceptedSuffix.add(".html");
        acceptedSuffix.add(".json");
        acceptedSuffix.add(".log");
    }

    @Override
    public String getName() {
        return VIEWER_NAME;
    }

    @Override
    public Set<Capability> getCapabilities(FileSystem fs, Path path) throws AccessControlException {
        return EnumSet.of(Capability.READ);
    }

    public void displayFile(FileSystem fs, Path path, OutputStream outputStream, int startLine, int endLine)
            throws IOException {

        if (logger.isDebugEnabled())
            logger.debug("read in uncompressed text file");

        InputStream inputStream = null;
        BufferedReader reader = null;
        try {
            inputStream = fs.open(path);
            reader = new BufferedReader(new InputStreamReader(inputStream));
            PrintWriter output = new PrintWriter(outputStream);
            for (int i = 1; i < startLine; i++)
                reader.readLine();

            // only display the first 1M chars. it is used to prevent
            // showing/downloading gb of data
            final int bufferLimit = 1000000;

            int bufferSize = 0;
            for (int i = startLine; i < endLine; i++) {
                String line = reader.readLine();
                if (line == null)
                    break;

                // bread if reach the buffer limit
                bufferSize += line.length();
                if (bufferSize >= bufferLimit)
                    break;

                output.write(line);
                output.write("\n");
            }
            output.flush();
        } finally {
            if (reader != null) {
                reader.close();
            }
            if (inputStream != null) {
                inputStream.close();
            }
        }
    }
}