/**
* 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.OutputStream;
import org.apache.hadoop.hdfs.util.XMLUtils;
import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;
import com.sun.org.apache.xml.internal.serialize.OutputFormat;
import com.sun.org.apache.xml.internal.serialize.XMLSerializer;
/**
* An XmlEditsVisitor walks over an EditLog structure and writes out
* an equivalent XML document that contains the EditLog's components.
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class XmlEditsVisitor implements OfflineEditsVisitor {
private final OutputStream out;
private ContentHandler contentHandler;
/**
* 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 XmlEditsVisitor(OutputStream out)
throws IOException {
this.out = out;
OutputFormat outFormat = new OutputFormat("XML", "UTF-8", true);
outFormat.setIndenting(true);
outFormat.setIndent(2);
outFormat.setDoctype(null, null);
XMLSerializer serializer = new XMLSerializer(out, outFormat);
contentHandler = serializer.asContentHandler();
try {
contentHandler.startDocument();
contentHandler.startElement("", "", "EDITS", new AttributesImpl());
} catch (SAXException e) {
throw new IOException("SAX error: " + e.getMessage());
}
}
/**
* Start visitor (initialization)
*/
@Override
public void start(int version) throws IOException {
try {
contentHandler.startElement("", "", "EDITS_VERSION", new AttributesImpl());
StringBuilder bld = new StringBuilder();
bld.append(version);
addString(bld.toString());
contentHandler.endElement("", "", "EDITS_VERSION");
}
catch (SAXException e) {
throw new IOException("SAX error: " + e.getMessage());
}
}
public void addString(String str) throws SAXException {
int slen = str.length();
char arr[] = new char[slen];
str.getChars(0, slen, arr, 0);
contentHandler.characters(arr, 0, slen);
}
/**
* Finish visitor
*/
@Override
public void close(Throwable error) throws IOException {
try {
contentHandler.endElement("", "", "EDITS");
if (error != null) {
String msg = error.getMessage();
XMLUtils.addSaxString(contentHandler, "ERROR",
(msg == null) ? "null" : msg);
}
contentHandler.endDocument();
}
catch (SAXException e) {
throw new IOException("SAX error: " + e.getMessage());
}
out.close();
}
@Override
public void visitOp(FSEditLogOp op) throws IOException {
try {
op.outputToXml(contentHandler);
}
catch (SAXException e) {
throw new IOException("SAX error: " + e.getMessage());
}
}
}