| /** |
| * Copyright 2005 The Apache Software Foundation |
| * |
| * 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.apache.nutch.util; |
| |
| import java.io.ByteArrayOutputStream; |
| import java.io.ByteArrayInputStream; |
| import java.io.IOException; |
| import java.lang.invoke.MethodHandles; |
| import java.util.zip.Inflater; |
| import java.util.zip.InflaterInputStream; |
| import java.util.zip.DeflaterOutputStream; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * A collection of utility methods for working on deflated data. |
| */ |
| public class DeflateUtils { |
| |
| private static final Logger LOG = LoggerFactory |
| .getLogger(MethodHandles.lookup().lookupClass()); |
| private static final int EXPECTED_COMPRESSION_RATIO = 5; |
| private static final int BUF_SIZE = 4096; |
| |
| /** |
| * Returns an inflated copy of the input array. If the deflated input has been |
| * truncated or corrupted, a best-effort attempt is made to inflate as much as |
| * possible. If no data can be extracted <code>null</code> is returned. |
| */ |
| public static final byte[] inflateBestEffort(byte[] in) { |
| return inflateBestEffort(in, Integer.MAX_VALUE); |
| } |
| |
| /** |
| * Returns an inflated copy of the input array, truncated to |
| * <code>sizeLimit</code> bytes, if necessary. If the deflated input has been |
| * truncated or corrupted, a best-effort attempt is made to inflate as much as |
| * possible. If no data can be extracted <code>null</code> is returned. |
| */ |
| public static final byte[] inflateBestEffort(byte[] in, int sizeLimit) { |
| // decompress using InflaterInputStream |
| ByteArrayOutputStream outStream = new ByteArrayOutputStream( |
| EXPECTED_COMPRESSION_RATIO * in.length); |
| |
| // "true" because HTTP does not provide zlib headers |
| Inflater inflater = new Inflater(true); |
| InflaterInputStream inStream = new InflaterInputStream( |
| new ByteArrayInputStream(in), inflater); |
| |
| byte[] buf = new byte[BUF_SIZE]; |
| int written = 0; |
| while (true) { |
| try { |
| int size = inStream.read(buf); |
| if (size <= 0) |
| break; |
| if ((written + size) > sizeLimit) { |
| outStream.write(buf, 0, sizeLimit - written); |
| break; |
| } |
| outStream.write(buf, 0, size); |
| written += size; |
| } catch (Exception e) { |
| LOG.info("Caught Exception in inflateBestEffort", e); |
| break; |
| } |
| } |
| try { |
| outStream.close(); |
| } catch (IOException e) { |
| } |
| |
| return outStream.toByteArray(); |
| } |
| |
| /** |
| * Returns an inflated copy of the input array. |
| * |
| * @throws IOException |
| * if the input cannot be properly decompressed |
| */ |
| public static final byte[] inflate(byte[] in) throws IOException { |
| // decompress using InflaterInputStream |
| ByteArrayOutputStream outStream = new ByteArrayOutputStream( |
| EXPECTED_COMPRESSION_RATIO * in.length); |
| |
| InflaterInputStream inStream = new InflaterInputStream( |
| new ByteArrayInputStream(in)); |
| |
| byte[] buf = new byte[BUF_SIZE]; |
| while (true) { |
| int size = inStream.read(buf); |
| if (size <= 0) |
| break; |
| outStream.write(buf, 0, size); |
| } |
| outStream.close(); |
| |
| return outStream.toByteArray(); |
| } |
| |
| /** |
| * Returns a deflated copy of the input array. |
| */ |
| public static final byte[] deflate(byte[] in) { |
| // compress using DeflaterOutputStream |
| ByteArrayOutputStream byteOut = new ByteArrayOutputStream(in.length |
| / EXPECTED_COMPRESSION_RATIO); |
| |
| DeflaterOutputStream outStream = new DeflaterOutputStream(byteOut); |
| |
| try { |
| outStream.write(in); |
| } catch (Exception e) { |
| LOG.error("Error compressing: ", e); |
| } |
| |
| try { |
| outStream.close(); |
| } catch (IOException e) { |
| LOG.error("Error closing: ", e); |
| } |
| |
| return byteOut.toByteArray(); |
| } |
| } |