Java tutorial
/* * 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.lucene.store; import java.io.IOException; import java.util.zip.CRC32; import java.util.zip.Checksum; /** * Simple implementation of {@link ChecksumIndexInput} that wraps * another input and delegates calls. */ public class BufferedChecksumIndexInput extends ChecksumIndexInput { final IndexInput main; final Checksum digest; /** Creates a new BufferedChecksumIndexInput */ public BufferedChecksumIndexInput(IndexInput main) { super("BufferedChecksumIndexInput(" + main + ")"); this.main = main; this.digest = new BufferedChecksum(new CRC32()); } @Override public byte readByte() throws IOException { final byte b = main.readByte(); digest.update(b); return b; } @Override public void readBytes(byte[] b, int offset, int len) throws IOException { main.readBytes(b, offset, len); digest.update(b, offset, len); } @Override public long getChecksum() { return digest.getValue(); } @Override public void close() throws IOException { main.close(); } @Override public long getFilePointer() { return main.getFilePointer(); } @Override public long length() { return main.length(); } @Override public IndexInput clone() { throw new UnsupportedOperationException(); } @Override public IndexInput slice(String sliceDescription, long offset, long length) throws IOException { throw new UnsupportedOperationException(); } }