001/** 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019package org.apache.oozie.util; 020 021import java.io.File; 022import java.io.FileInputStream; 023import java.io.FileReader; 024import java.io.IOException; 025import java.io.InputStreamReader; 026import java.io.Reader; 027import java.util.ArrayList; 028import java.util.zip.GZIPInputStream; 029 030/** 031 * Implementation of a {@link Reader} which can be used to read in multiple files sequentially. That is, when the first file ends 032 * 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 033 * other types of files will simply be read using a {@link FileReader}. 034 */ 035public class MultiFileReader extends Reader { 036 037 private ArrayList<File> files; 038 private int index; 039 private Reader reader; 040 private boolean closed; 041 042 /** 043 * Constructs the MultiFileReader with the given files. The files will be read in the order given in the ArrayList. 044 * 045 * @param files The files to read 046 * @throws IOException If there was a problem opening the first file 047 */ 048 public MultiFileReader(ArrayList<File> files) throws IOException { 049 this.files = files; 050 closed = false; 051 index = 0; 052 reader = null; 053 openNextReader(); 054 } 055 056 @Override 057 public int read(char[] cbuf, int off, int len) throws IOException { 058 int numRead = -1; 059 while(!closed && numRead == -1) { 060 numRead = reader.read(cbuf, off, len); 061 if (numRead == -1) { 062 reader.close(); 063 openNextReader(); 064 } 065 } 066 return numRead; 067 } 068 069 @Override 070 public void close() throws IOException { 071 if (reader != null) { 072 reader.close(); 073 } 074 closed = true; 075 } 076 077 private void openNextReader() throws IOException { 078 if (index < files.size()) { 079 // gzip files 080 if (files.get(index).getName().endsWith(".gz")) { 081 GZIPInputStream gzipInputStream = new GZIPInputStream(new FileInputStream(files.get(index))); 082 reader = new InputStreamReader(gzipInputStream); 083 } 084 // regular files 085 else { 086 reader = new FileReader(files.get(index)); 087 } 088 index++; 089 } 090 else { 091 closed = true; 092 } 093 } 094}