/**
* 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.ambari.view.filebrowser;
import org.apache.ambari.view.ViewContext;
import org.apache.ambari.view.commons.exceptions.NotFoundFormattedException;
import org.apache.ambari.view.commons.exceptions.ServiceFormattedException;
import org.apache.ambari.view.commons.hdfs.HdfsService;
import org.apache.ambari.view.utils.hdfs.HdfsApi;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.CompressionCodecFactory;
import org.json.simple.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.ws.rs.*;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.util.Map;
/**
* File Preview Service
*/
public class FilePreviewService extends HdfsService {
protected static final Logger LOG = LoggerFactory.getLogger(FilePreviewService.class);
private CompressionCodecFactory compressionCodecFactory;
public FilePreviewService(ViewContext context) {
super(context);
initCompressionCodecFactory();
}
private void initCompressionCodecFactory() {
Configuration conf = new Configuration();
conf.set("io.compression.codecs","org.apache.hadoop.io.compress.GzipCodec," +
"org.apache.hadoop.io.compress.DefaultCodec,org.apache.hadoop.io.compress.SnappyCodec," +
"org.apache.hadoop.io.compress.BZip2Codec");
compressionCodecFactory = new CompressionCodecFactory(conf);
}
/**
* @param context
* @param viewConfigs : extra properties that needs to be included into configs
*/
public FilePreviewService(ViewContext context, Map<String, String> viewConfigs) {
super(context, viewConfigs);
initCompressionCodecFactory();
}
@GET
@Path("/file")
@Produces(MediaType.APPLICATION_JSON)
public Response previewFile(@QueryParam("path") String path, @QueryParam("start") int start, @QueryParam("end") int end) {
LOG.info("previewing file {}, from start {}, till end {}", path, start, end);
try {
HdfsApi api = getApi();
FileStatus status = api.getFileStatus(path);
CompressionCodec codec = compressionCodecFactory.getCodec(status.getPath());
// check if we have a compression codec we need to use
InputStream stream = (codec != null) ? codec.createInputStream(api.open(path)) : api.open(path);
int length = end - start;
byte[] bytes = new byte[length];
if (start != 0) IOUtils.skip(stream, start);
int readBytes = IOUtils.read(stream, bytes);
boolean isFileEnd = false;
if (readBytes < length) isFileEnd = true;
JSONObject response = new JSONObject();
response.put("data", new String(bytes));
response.put("readbytes", readBytes);
response.put("isFileEnd", isFileEnd);
return Response.ok(response).build();
} catch (WebApplicationException ex) {
LOG.error("Error occurred while previewing {} : ", path, ex);
throw ex;
} catch (FileNotFoundException ex) {
LOG.error("Error occurred while previewing {} : ", path, ex);
throw new NotFoundFormattedException(ex.getMessage(), ex);
} catch (Exception ex) {
LOG.error("Error occurred while previewing {} : ", path, ex);
throw new ServiceFormattedException(ex.getMessage(), ex);
}
}
}