tests/honeynode/2.1/netconf-netty-util/src/main/java/org/opendaylight/netconf/nettyutil/handler/ThreadLocalTransformers.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.netconf.nettyutil.handler;
   9
  10 import javax.xml.transform.OutputKeys;
  11 import javax.xml.transform.Transformer;
  12 import javax.xml.transform.TransformerConfigurationException;
  13 import javax.xml.transform.TransformerFactory;
  14 import javax.xml.transform.TransformerFactoryConfigurationError;
  15
  16 /**
  17  * Utility class for cached thread-local transformers. This class exists mostly for use by handlers.
  18  */
  19 final class ThreadLocalTransformers {
  20     private static final TransformerFactory FACTORY = TransformerFactory.newInstance();
  21
  22     private static final ThreadLocal<Transformer> DEFAULT_TRANSFORMER = new ThreadLocal<Transformer>() {
  23         @Override
  24         protected Transformer initialValue() {
  25             return createTransformer();
  26         }
  27
  28         @Override
  29         public void set(final Transformer value) {
  30             throw new UnsupportedOperationException();
  31         }
  32     };
  33
  34     private static final ThreadLocal<Transformer> PRETTY_TRANSFORMER = new ThreadLocal<Transformer>() {
  35         @Override
  36         protected Transformer initialValue() {
  37             final Transformer ret = createTransformer();
  38             ret.setOutputProperty(OutputKeys.INDENT, "yes");
  39             ret.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
  40             return ret;
  41         }
  42
  43         @Override
  44         public void set(final Transformer value) {
  45             throw new UnsupportedOperationException();
  46         }
  47     };
  48
  49     private ThreadLocalTransformers() {
  50         throw new UnsupportedOperationException("Utility class");
  51     }
  52
  53     /**
  54      * Get the transformer with default configuration.
  55      *
  56      * @return A transformer with default configuration based on the default implementation.
  57      */
  58     static Transformer getDefaultTransformer() {
  59         return DEFAULT_TRANSFORMER.get();
  60     }
  61
  62     /**
  63      * Get the transformer with default configuration, but with automatic indentation
  64      * and the XML declaration removed.
  65      *
  66      * @return A transformer with human-friendly configuration.
  67      */
  68     static Transformer getPrettyTransformer() {
  69         return PRETTY_TRANSFORMER.get();
  70     }
  71
  72     private static Transformer createTransformer() {
  73         try {
  74             return FACTORY.newTransformer();
  75         } catch (TransformerConfigurationException | TransformerFactoryConfigurationError e) {
  76             throw new IllegalStateException("Unexpected error while instantiating a Transformer", e);
  77         }
  78     }
  79 }