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Java 1.8+ Library with XML handling routines
/*
* Copyright (C) 2014-2024 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* Licensed 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 com.helger.xml.microdom.util;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Collection;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.WillClose;
import javax.annotation.concurrent.Immutable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.PresentForCodeCoverage;
import com.helger.commons.annotation.ReturnsMutableCopy;
import com.helger.commons.collection.impl.CommonsArrayList;
import com.helger.commons.collection.impl.ICommonsList;
import com.helger.commons.io.EAppend;
import com.helger.commons.io.IHasInputStream;
import com.helger.commons.io.IHasOutputStream;
import com.helger.commons.io.stream.StreamHelper;
import com.helger.commons.state.ESuccess;
import com.helger.xml.microdom.IMicroDocument;
import com.helger.xml.microdom.IMicroElement;
import com.helger.xml.microdom.MicroDocument;
import com.helger.xml.microdom.serialize.MicroReader;
import com.helger.xml.microdom.serialize.MicroWriter;
import com.helger.xml.serialize.write.XMLWriterSettings;
/**
* Simple class that reads a list from an XML input stream.
* The XML file needs to look as follows:
*
*
* <list>
* <item value="..."/>
* <item value="..."/>
* ...
* </list>
*
*
* @author Philip Helger
*/
@Immutable
public final class XMLListHandler
{
/** Name of the root element */
public static final String ELEMENT_LIST = "list";
/** Element name of a single item */
public static final String ELEMENT_ITEM = "item";
/** Attribute name for the item value */
public static final String ATTR_VALUE = "value";
private static final Logger LOGGER = LoggerFactory.getLogger (XMLListHandler.class);
@PresentForCodeCoverage
private static final XMLListHandler INSTANCE = new XMLListHandler ();
private XMLListHandler ()
{}
@Nullable
@ReturnsMutableCopy
public static ICommonsList readList (@Nonnull final IHasInputStream aISP)
{
ValueEnforcer.notNull (aISP, "InputStreamProvider");
return readList (aISP.getInputStream ());
}
@Nonnull
public static ESuccess readList (@Nonnull final IHasInputStream aISP, @Nonnull final Collection aTargetList)
{
ValueEnforcer.notNull (aISP, "InputStreamProvider");
return readList (aISP.getInputStream (), aTargetList);
}
/**
* Read a predefined XML file that contains list items.
*
* @param aIS
* The input stream to read from. May not be null.
* Automatically closed no matter whether reading succeeded or not.
* @return null if reading fails - all list items otherwise.
*/
@Nullable
@ReturnsMutableCopy
public static ICommonsList readList (@Nonnull @WillClose final InputStream aIS)
{
final ICommonsList ret = new CommonsArrayList <> ();
if (readList (aIS, ret).isFailure ())
return null;
return ret;
}
/**
* Read a predefined XML file that contains list items.
*
* @param aIS
* The input stream to read from. May not be null.
* Automatically closed no matter whether reading succeeded or not.
* @param aTargetList
* The target collection to be filled. May not be null.
* @return {@link ESuccess#SUCCESS} if reading succeeded,
* {@link ESuccess#FAILURE} if the input stream is no valid XML or any
* other error occurred.
*/
@Nonnull
public static ESuccess readList (@Nonnull @WillClose final InputStream aIS,
@Nonnull final Collection aTargetList)
{
ValueEnforcer.notNull (aIS, "InputStream");
ValueEnforcer.notNull (aTargetList, "TargetList");
try
{
// open file
final IMicroDocument aDoc = MicroReader.readMicroXML (aIS);
if (aDoc != null)
{
readList (aDoc.getDocumentElement (), aTargetList);
return ESuccess.SUCCESS;
}
}
catch (final Exception ex)
{
LOGGER.warn ("Failed to read list resource '" + aIS + "'", ex);
}
finally
{
StreamHelper.close (aIS);
}
return ESuccess.FAILURE;
}
@Nonnull
public static ESuccess readList (@Nonnull final IMicroElement aParentElement,
@Nonnull final Collection aTargetList)
{
ValueEnforcer.notNull (aParentElement, "ParentElement");
ValueEnforcer.notNull (aTargetList, "TargetList");
try
{
// and insert all elements
for (final IMicroElement eItem : aParentElement.getAllChildElements (ELEMENT_ITEM))
{
final String sValue = eItem.getAttributeValue (ATTR_VALUE);
if (sValue == null)
LOGGER.warn ("Ignoring list item because value is null");
else
if (!aTargetList.add (sValue))
LOGGER.warn ("Ignoring list item '" + sValue + "' because value is already contained");
}
return ESuccess.SUCCESS;
}
catch (final Exception ex)
{
LOGGER.warn ("Failed to read list document", ex);
}
return ESuccess.FAILURE;
}
@Nonnull
public static IMicroDocument createListDocument (@Nonnull final Collection aCollection)
{
ValueEnforcer.notNull (aCollection, "Collection");
final IMicroDocument aDoc = new MicroDocument ();
final IMicroElement eRoot = aDoc.appendElement (ELEMENT_LIST);
for (final String sItem : aCollection)
{
final IMicroElement eItem = eRoot.appendElement (ELEMENT_ITEM);
eItem.setAttribute (ATTR_VALUE, sItem);
}
return aDoc;
}
@Nonnull
public static ESuccess writeList (@Nonnull final Collection aCollection,
@Nonnull final IHasOutputStream aOSP)
{
ValueEnforcer.notNull (aOSP, "OutputStreamProvider");
return writeList (aCollection, aOSP.getOutputStream (EAppend.DEFAULT));
}
/**
* Write the passed collection to the passed output stream using the
* predefined XML layout.
*
* @param aCollection
* The map to be written. May not be null.
* @param aOS
* The output stream to write to. The stream is closed independent of
* success or failure. May not be null.
* @return {@link ESuccess#SUCCESS} when everything went well,
* {@link ESuccess#FAILURE} otherwise.
*/
@Nonnull
public static ESuccess writeList (@Nonnull final Collection aCollection,
@Nonnull @WillClose final OutputStream aOS)
{
ValueEnforcer.notNull (aCollection, "Collection");
ValueEnforcer.notNull (aOS, "OutputStream");
try
{
final IMicroDocument aDoc = createListDocument (aCollection);
return MicroWriter.writeToStream (aDoc, aOS, XMLWriterSettings.DEFAULT_XML_SETTINGS);
}
finally
{
StreamHelper.close (aOS);
}
}
}