| /** |
| * 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.offlineEditsViewer; |
| |
| import java.io.IOException; |
| import java.io.FileNotFoundException; |
| import java.io.FileInputStream; |
| |
| import javax.xml.stream.XMLStreamException; |
| import javax.xml.stream.XMLStreamConstants; |
| import javax.xml.stream.XMLInputFactory; |
| import javax.xml.stream.XMLStreamReader; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * Tokenizer that reads tokens from XML file |
| * |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public class XmlTokenizer implements Tokenizer { |
| |
| FileInputStream is = null; |
| XMLStreamReader in; |
| |
| /** |
| * XmlTokenizer constructor |
| * |
| * @param filename input filename |
| */ |
| public XmlTokenizer(String filename) throws IOException { |
| XMLInputFactory f = XMLInputFactory.newInstance(); |
| // FileInputStream is = null; |
| try { |
| is = new FileInputStream(filename); |
| in = f.createXMLStreamReader(is); |
| } catch(XMLStreamException e) { |
| // if(is != null) { is.close(); } |
| throw new IOException("Cannot create XML stream", e); |
| } catch(FileNotFoundException e) { |
| //if(is != null) { is.close(); } |
| throw new IOException("Cannot open input file " + filename, e); |
| } |
| } |
| |
| /** |
| * Get next element's value, checks that the element's name |
| * is wantedName. |
| * |
| * @param wantedName a name of node that we are looking for |
| */ |
| private String getNextElementsValue(String wantedName) throws IOException { |
| boolean gotSTART_ELEMENT = false; |
| try { |
| int eventType = in.getEventType(); |
| while(true) { |
| switch(eventType) { |
| case XMLStreamConstants.CHARACTERS: // 4 |
| if(gotSTART_ELEMENT) { |
| // XML returns "\n" instead of empty (zero-length) string |
| // for elements like <x></x> |
| return in.getText().trim(); |
| } |
| break; |
| case XMLStreamConstants.END_DOCUMENT: // 8 |
| throw new IOException("End of XML while looking for element [" + |
| wantedName + "]"); |
| // break; |
| case XMLStreamConstants.START_ELEMENT : // 1 |
| if(gotSTART_ELEMENT) { |
| throw new IOException("START_ELEMENT [" + |
| in.getName() + |
| " event when expecting CHARACTERS event for [" + |
| wantedName + "]"); |
| } else if(in.getName().toString().equals(wantedName)) { |
| gotSTART_ELEMENT = true; |
| } else { |
| throw new IOException("unexpected element name [" + |
| in.getName() + "], was expecting [" + |
| wantedName + "]"); |
| } |
| break; |
| case XMLStreamConstants.COMMENT: |
| case XMLStreamConstants.END_ELEMENT: // 2 |
| case XMLStreamConstants.SPACE: |
| case XMLStreamConstants.START_DOCUMENT: // 7 |
| // these are in XML but we don't need them |
| break; |
| // these should never appear in edits XML |
| case XMLStreamConstants.ATTRIBUTE: |
| case XMLStreamConstants.CDATA: |
| case XMLStreamConstants.DTD: |
| case XMLStreamConstants.ENTITY_DECLARATION: |
| case XMLStreamConstants.ENTITY_REFERENCE: |
| case XMLStreamConstants.NAMESPACE: |
| case XMLStreamConstants.NOTATION_DECLARATION: |
| case XMLStreamConstants.PROCESSING_INSTRUCTION: |
| default: |
| throw new IOException("Unsupported event type [" + |
| eventType + "] (see XMLStreamConstants)"); |
| } |
| if(!in.hasNext()) { break; } |
| eventType = in.next(); |
| } |
| } catch(XMLStreamException e) { |
| throw new IOException("Error reading XML stream", e); |
| } |
| throw new IOException( |
| "Error reading XML stream, should never reach this line, " + |
| "most likely XML does not have elements we are loking for"); |
| } |
| |
| /** |
| * @see org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer#read |
| * |
| * @param t a token to read |
| * @return token that was just read |
| */ |
| public Token read(Token t) throws IOException { |
| t.fromString(getNextElementsValue(t.getEditsElement().toString())); |
| return t; |
| } |
| } |