| /** |
| * 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.oozie.util; |
| |
| import java.io.File; |
| import java.io.FileInputStream; |
| import java.io.FileReader; |
| import java.io.IOException; |
| import java.io.InputStreamReader; |
| import java.io.Reader; |
| import java.nio.charset.StandardCharsets; |
| import java.util.ArrayList; |
| import java.util.zip.GZIPInputStream; |
| |
| /** |
| * Implementation of a {@link Reader} which can be used to read in multiple files sequentially. That is, when the first file ends |
| * it will silently move to the next file and so on. If the file has a ".gz" extension, this Reader will properly handle it; all |
| * other types of files will simply be read using a {@link FileReader}. |
| */ |
| public class MultiFileReader extends Reader { |
| |
| private ArrayList<File> files; |
| private int index; |
| private Reader reader; |
| private boolean closed; |
| |
| /** |
| * Constructs the MultiFileReader with the given files. The files will be read in the order given in the ArrayList. |
| * |
| * @param files The files to read |
| * @throws IOException If there was a problem opening the first file |
| */ |
| public MultiFileReader(ArrayList<File> files) throws IOException { |
| this.files = files; |
| closed = false; |
| index = 0; |
| reader = null; |
| openNextReader(); |
| } |
| |
| @Override |
| public int read(char[] cbuf, int off, int len) throws IOException { |
| int numRead = -1; |
| while(!closed && numRead == -1) { |
| numRead = reader.read(cbuf, off, len); |
| if (numRead == -1) { |
| reader.close(); |
| openNextReader(); |
| } |
| } |
| return numRead; |
| } |
| |
| @Override |
| public void close() throws IOException { |
| if (reader != null) { |
| reader.close(); |
| } |
| closed = true; |
| } |
| |
| private void openNextReader() throws IOException { |
| if (index < files.size()) { |
| // gzip files |
| if (files.get(index).getName().endsWith(".gz")) { |
| GZIPInputStream gzipInputStream = new GZIPInputStream(new FileInputStream(files.get(index))); |
| reader = new InputStreamReader(gzipInputStream, StandardCharsets.UTF_8); |
| } |
| // regular files |
| else { |
| reader = new InputStreamReader(new FileInputStream(files.get(index)), StandardCharsets.UTF_8); |
| } |
| index++; |
| } |
| else { |
| closed = true; |
| } |
| } |
| } |