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WarcRecordUtils.java
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Tue, May 7, 12:52

WarcRecordUtils.java
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/*
* Warcbase: an open-source platform for managing web archives
*
* 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 org.warcbase.data;
import org.apache.commons.httpclient.HttpParser;
import org.apache.log4j.Logger;
import org.archive.io.warc.WARCConstants;
import org.archive.io.warc.WARCReader;
import org.archive.io.warc.WARCReaderFactory;
import org.archive.io.warc.WARCRecord;
import java.io.*;
import java.lang.Exception;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Utilities for working with {@code WARCRecord}s (from archive.org APIs).
*/
public class WarcRecordUtils implements WARCConstants {
private static final Logger LOG = Logger.getLogger(WarcRecordUtils.class);
// TODO: these methods work fine, but there's a lot of unnecessary buffer copying, which is
// terrible from a performance perspective.
/**
* Converts raw bytes into an {@code WARCRecord}.
*
* @param bytes raw bytes
* @return parsed {@code WARCRecord}
* @throws IOException
*/
public static WARCRecord fromBytes(byte[] bytes) throws IOException {
WARCReader reader = (WARCReader) WARCReaderFactory.get("",
new BufferedInputStream(new ByteArrayInputStream(bytes)), false);
return (WARCRecord) reader.get();
}
public static byte[] toBytes(WARCRecord record) throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dout = new DataOutputStream(baos);
dout.write("WARC/0.17\n".getBytes());
for (Map.Entry<String, Object> entry : record.getHeader().getHeaderFields().entrySet()) {
dout.write((entry.getKey() + ": " + entry.getValue().toString() + "\n").getBytes());
}
dout.write("\n".getBytes());
record.dump(dout);
return baos.toByteArray();
}
/**
* Extracts the MIME type of WARC response records (i.e., "WARC-Type" is "response").
* Note that this is different from the "Content-Type" in the WARC header.
*
* @param contents raw contents of the WARC response record
* @return MIME type
*/
public static String getWarcResponseMimeType(byte[] contents) {
// This is a somewhat janky way to get the MIME type of the response.
// Note that this is different from the "Content-Type" in the WARC header.
Pattern pattern = Pattern.compile("Content-Type: ([^\\s]+)", Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(new String(contents));
if (matcher.find()) {
return matcher.group(1).replaceAll(";$", "");
}
return null;
}
/**
* Extracts raw contents from a {@code WARCRecord} (including HTTP headers).
*
* @param record the {@code WARCRecord}
* @return raw contents
* @throws IOException
*/
public static byte[] getContent(WARCRecord record) throws IOException {
int len = (int) record.getHeader().getContentLength();
// If we have a corrupt record, quit and move on.
if (len < 0) {
return new byte[0];
}
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dout = new DataOutputStream(baos);
copyStream(record, len, true, dout);
return baos.toByteArray();
} catch (Exception e) {
// Catch exceptions related to any corrupt archive files.
return new byte[0];
}
}
/**
* Extracts contents of the body from a {@code WARCRecord} (excluding HTTP headers).
*
* @param record the {@code WARCRecord}
* @return contents of the body
* @throws IOException
*/
public static byte[] getBodyContent(WARCRecord record) throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
String line = HttpParser.readLine(record, WARC_HEADER_ENCODING);
if (line == null) {
return null;
}
// Just using parseHeaders to move down input stream to body
HttpParser.parseHeaders(record, WARC_HEADER_ENCODING);
record.dump(baos);
return baos.toByteArray();
}
private static long copyStream(final InputStream is, final int recordLength,
boolean enforceLength, final DataOutputStream out) throws IOException {
byte [] scratchbuffer = new byte[recordLength];
int read = 0;
long tot = 0;
while ((tot < recordLength) && (read = is.read(scratchbuffer)) != -1) {
int write = read;
// never write more than enforced length
write = (int) Math.min(write, recordLength - tot);
tot += read;
out.write(scratchbuffer, 0, write);
}
if (enforceLength && tot != recordLength) {
LOG.error("Read " + tot + " bytes but expected " + recordLength + " bytes. Continuing...");
}
return tot;
}
}

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