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 */ 018package org.apache.hadoop.hdfs.tools.offlineImageViewer; 019 020import java.io.IOException; 021import java.util.LinkedList; 022 023/** 024 * An XmlImageVisitor walks over an fsimage structure and writes out 025 * an equivalent XML document that contains the fsimage's components. 026 */ 027public class XmlImageVisitor extends TextWriterImageVisitor { 028 final private LinkedList<ImageElement> tagQ = 029 new LinkedList<ImageElement>(); 030 031 public XmlImageVisitor(String filename) throws IOException { 032 super(filename, false); 033 } 034 035 public XmlImageVisitor(String filename, boolean printToScreen) 036 throws IOException { 037 super(filename, printToScreen); 038 } 039 040 @Override 041 void finish() throws IOException { 042 super.finish(); 043 } 044 045 @Override 046 void finishAbnormally() throws IOException { 047 write("\n<!-- Error processing image file. Exiting -->\n"); 048 super.finishAbnormally(); 049 } 050 051 @Override 052 void leaveEnclosingElement() throws IOException { 053 if(tagQ.size() == 0) 054 throw new IOException("Tried to exit non-existent enclosing element " + 055 "in FSImage file"); 056 057 ImageElement element = tagQ.pop(); 058 write("</" + element.toString() + ">\n"); 059 } 060 061 @Override 062 void start() throws IOException { 063 write("<?xml version=\"1.0\" ?>\n"); 064 } 065 066 @Override 067 void visit(ImageElement element, String value) throws IOException { 068 writeTag(element.toString(), value); 069 } 070 071 @Override 072 void visitEnclosingElement(ImageElement element) throws IOException { 073 write("<" + element.toString() + ">\n"); 074 tagQ.push(element); 075 } 076 077 @Override 078 void visitEnclosingElement(ImageElement element, 079 ImageElement key, String value) 080 throws IOException { 081 write("<" + element.toString() + " " + key + "=\"" + value +"\">\n"); 082 tagQ.push(element); 083 } 084 085 private void writeTag(String tag, String value) throws IOException { 086 write("<" + tag + ">" + value + "</" + tag + ">\n"); 087 } 088}