| /** |
| * 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.hadoop.hdfs.tools.offlineImageViewer; |
| |
| import java.io.FileWriter; |
| import java.io.IOException; |
| |
| /** |
| * TextWriterImageProcessor mixes in the ability for ImageVisitor |
| * implementations to easily write their output to a text file. |
| * |
| * Implementing classes should be sure to call the super methods for the |
| * constructors, finish and finishAbnormally methods, in order that the |
| * underlying file may be opened and closed correctly. |
| * |
| * Note, this class does not add newlines to text written to file or (if |
| * enabled) screen. This is the implementing class' responsibility. |
| */ |
| abstract class TextWriterImageVisitor extends ImageVisitor { |
| private boolean printToScreen = false; |
| private boolean okToWrite = false; |
| final private FileWriter fw; |
| |
| /** |
| * Create a processor that writes to the file named. |
| * |
| * @param filename Name of file to write output to |
| */ |
| public TextWriterImageVisitor(String filename) throws IOException { |
| this(filename, false); |
| } |
| |
| /** |
| * Create a processor that writes to the file named and may or may not |
| * also output to the screen, as specified. |
| * |
| * @param filename Name of file to write output to |
| * @param printToScreen Mirror output to screen? |
| */ |
| public TextWriterImageVisitor(String filename, boolean printToScreen) |
| throws IOException { |
| super(); |
| this.printToScreen = printToScreen; |
| fw = new FileWriter(filename); |
| okToWrite = true; |
| } |
| |
| /* (non-Javadoc) |
| * @see org.apache.hadoop.hdfs.tools.offlineImageViewer.ImageVisitor#finish() |
| */ |
| @Override |
| void finish() throws IOException { |
| close(); |
| } |
| |
| /* (non-Javadoc) |
| * @see org.apache.hadoop.hdfs.tools.offlineImageViewer.ImageVisitor#finishAbnormally() |
| */ |
| @Override |
| void finishAbnormally() throws IOException { |
| close(); |
| } |
| |
| /** |
| * Close output stream and prevent further writing |
| */ |
| private void close() throws IOException { |
| fw.close(); |
| okToWrite = false; |
| } |
| |
| /** |
| * Write parameter to output file (and possibly screen). |
| * |
| * @param toWrite Text to write to file |
| */ |
| protected void write(String toWrite) throws IOException { |
| if(!okToWrite) |
| throw new IOException("file not open for writing."); |
| |
| if(printToScreen) |
| System.out.print(toWrite); |
| |
| try { |
| fw.write(toWrite); |
| } catch (IOException e) { |
| okToWrite = false; |
| throw e; |
| } |
| } |
| } |