Class XMLConfiguration
- All Implemented Interfaces:
Cloneable,Configuration,EventSource,FileBasedConfiguration,HierarchicalConfiguration<ImmutableNode>,ImmutableConfiguration,ImmutableHierarchicalConfiguration,FileBased,FileLocatorAware,InputStreamSupport,SynchronizerSupport,InMemoryNodeModelSupport,NodeKeyResolver<ImmutableNode>,NodeModelSupport<ImmutableNode>
A specialized hierarchical configuration class that is able to parse XML documents.
The parsed document will be stored keeping its structure. The class also tries to preserve as much information from
the loaded XML document as possible, including comments and processing instructions. These will be contained in
documents created by the save() methods, too.
Like other file based configuration classes this class maintains the name and path to the loaded configuration file.
These properties can be altered using several setter methods, but they are not modified by save() and
load() methods. If XML documents contain relative paths to other documents (for example to a DTD), these references
are resolved based on the path set for this configuration.
By inheriting from AbstractConfiguration this class provides some extended functionality, for example interpolation
of property values. Like in PropertiesConfiguration property values can contain delimiter characters (the
comma ',' per default) and are then split into multiple values. This works for XML attributes and text content of
elements as well. The delimiter can be escaped by a backslash. As an example consider the following XML fragment:
<config> <array>10,20,30,40</array> <scalar>3\,1415</scalar> <cite text="To be or not to be\, this is the question!"/> </config>
Here the content of the array element will be split at the commas, so the array key will be assigned
4 values. In the scalar property and the text attribute of the cite element the comma is
escaped, so that no splitting is performed.
The configuration API allows setting multiple values for a single attribute, for example something like the following is legal (assuming that the default expression engine is used):
XMLConfiguration config = new XMLConfiguration();
config.addProperty("test.dir[@name]", "C:\\Temp\\");
config.addProperty("test.dir[@name]", "D:\\Data\\");
However, in XML such a constellation is not supported; an attribute can appear only once for a single element. Therefore, an attempt to save a configuration which violates this condition will throw an exception.
Like other Configuration implementations, XMLConfiguration uses a ListDelimiterHandler object
for controlling list split operations. Per default, a list delimiter handler object is set which disables this
feature. XML has a built-in support for complex structures including list properties; therefore, list splitting is
not that relevant for this configuration type. Nevertheless, by setting an alternative ListDelimiterHandler
implementation, this feature can be enabled. It works as for any other concrete Configuration implementation.
Whitespace in the content of XML documents is trimmed per default. In most cases this is desired. However, sometimes whitespace is indeed important and should be treated as part of the value of a property as in the following example:
<indent> </indent>
Per default the spaces in the indent element will be trimmed resulting in an empty element. To tell
XMLConfiguration that spaces are relevant the xml:space attribute can be used, which is defined in
the XML specification. This will look as follows:
<indent xml:space="preserve"> </indent>
The value of the indent property will now contain the spaces.
XMLConfiguration implements the FileBasedConfiguration interface and thus can be used together with a
file-based builder to load XML configuration files from various sources like files, URLs, or streams.
Like other Configuration implementations, this class uses a Synchronizer object to control concurrent
access. By choosing a suitable implementation of the Synchronizer interface, an instance can be made
thread-safe or not. Note that access to most of the properties typically set through a builder is not protected by
the Synchronizer. The intended usage is that these properties are set once at construction time through the
builder and after that remain constant. If you wish to change such properties during life time of an instance, you
have to use the lock() and unlock() methods manually to ensure that other threads see your changes.
More information about the basic functionality supported by XMLConfiguration can be found at the user's guide
at Basic
features and AbstractConfiguration. There is also a separate chapter dealing with
XML Configurations in
special.
- Since:
- 1.0
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.commons.configuration2.BaseHierarchicalConfiguration
BaseHierarchicalConfiguration.BuilderVisitor -
Constructor Summary
ConstructorsConstructorDescriptionCreates a new instance ofXMLConfiguration.Creates a new instance ofXMLConfigurationand copies the content of the passed in configuration into this object. -
Method Summary
Modifier and TypeMethodDescriptionprotected DocumentBuilderCreates theDocumentBuilderto be used for loading files.protected TransformerCreates and initializes the transformer used for save operations.Gets the XML document this configuration was loaded from.Gets theDocumentBuilderobject that is used for loading documents.Gets the EntityResolver.Gets the public ID of the DOCTYPE declaration from the loaded XML document.protected StringGets the name of the root element.Gets the system ID of the DOCTYPE declaration from the loaded XML document.voidPasses the currentFileLocatorto this object.booleanReturns the value of the schemaValidation flag.booleanReturns the value of the validating flag.voidread(InputStream in) Loads the configuration from the given input stream.voidLoads the configuration from the given reader.voidsetDocumentBuilder(DocumentBuilder documentBuilder) Sets theDocumentBuilderobject to be used for loading documents.voidsetEntityResolver(EntityResolver resolver) Sets a new EntityResolver.voidsetPublicID(String publicID) Sets the public ID of the DOCTYPE declaration.voidsetRootElementName(String name) Sets the name of the root element.voidsetSchemaValidation(boolean schemaValidation) Sets the value of the schemaValidation flag.voidsetSystemID(String systemID) Sets the system ID of the DOCTYPE declaration.voidsetValidating(boolean validating) Sets the value of the validating flag.voidvalidate()Validate the document against the Schema.voidSaves the configuration to the specified writer.voidwrite(Writer writer, Transformer transformer) Saves the configuration to the specified writer.Methods inherited from class org.apache.commons.configuration2.BaseHierarchicalConfiguration
childConfigurationsAt, childConfigurationsAt, cloneNodeModel, configurationAt, configurationAt, configurationsAt, configurationsAt, createSubConfigurationForTrackedNode, getNodeModel, getSubConfigurationNodeSelector, getSubConfigurationParentModel, immutableChildConfigurationsAt, immutableConfigurationAt, immutableConfigurationAt, immutableConfigurationsAt, initSubConfigurationForThisParent, interpolatedConfiguration, subnodeConfigurationChanged, subsetMethods inherited from class org.apache.commons.configuration2.AbstractHierarchicalConfiguration
addNodes, addNodesInternal, addPropertyDirect, addPropertyInternal, clearInternal, clearPropertyDirect, clearTree, clearTreeInternal, clone, containsKeyInternal, containsValueInternal, fetchNodeList, getExpressionEngine, getKeysInternal, getKeysInternal, getKeysInternal, getMaxIndex, getMaxIndexInternal, getModel, getPropertyInternal, getRootElementName, isEmptyInternal, nodeDefined, nodeKey, resolveAddKey, resolveKey, resolveNodeKey, resolveUpdateKey, setExpressionEngine, setPropertyInternal, sizeInternal, toStringMethods inherited from class org.apache.commons.configuration2.AbstractConfiguration
addErrorLogListener, addProperty, append, beginRead, beginWrite, clear, clearProperty, cloneInterpolator, contains, containsKey, containsValue, copy, endRead, endWrite, get, get, getArray, getArray, getBigDecimal, getBigDecimal, getBigInteger, getBigInteger, getBoolean, getBoolean, getBoolean, getByte, getByte, getByte, getCollection, getCollection, getConfigurationDecoder, getConversionHandler, getDouble, getDouble, getDouble, getDuration, getDuration, getEncodedString, getEncodedString, getFloat, getFloat, getFloat, getInt, getInt, getInteger, getInterpolator, getKeys, getKeys, getKeys, getList, getList, getList, getList, getListDelimiterHandler, getLogger, getLong, getLong, getLong, getProperties, getProperties, getProperty, getShort, getShort, getShort, getString, getString, getStringArray, getSynchronizer, immutableSubset, initLogger, installInterpolator, interpolate, interpolate, isEmpty, isScalarValue, isThrowExceptionOnMissing, lock, setConfigurationDecoder, setConversionHandler, setDefaultLookups, setInterpolator, setListDelimiterHandler, setLogger, setParentInterpolator, setPrefixLookups, setProperty, setSynchronizer, setThrowExceptionOnMissing, size, unlockMethods inherited from class org.apache.commons.configuration2.event.BaseEventSource
addEventListener, clearErrorListeners, clearEventListeners, copyEventListeners, createErrorEvent, createEvent, fireError, fireEvent, getEventListenerRegistrations, getEventListeners, isDetailEvents, removeEventListener, setDetailEventsMethods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitMethods inherited from interface org.apache.commons.configuration2.Configuration
addProperty, clear, clearProperty, getInterpolator, installInterpolator, setInterpolator, setProperty, subsetMethods inherited from interface org.apache.commons.configuration2.ImmutableConfiguration
containsKey, containsValue, get, get, getArray, getArray, getBigDecimal, getBigDecimal, getBigInteger, getBigInteger, getBoolean, getBoolean, getBoolean, getByte, getByte, getByte, getCollection, getCollection, getDouble, getDouble, getDouble, getDuration, getDuration, getEncodedString, getEncodedString, getEnum, getEnum, getFloat, getFloat, getFloat, getInt, getInt, getInteger, getKeys, getKeys, getKeys, getList, getList, getList, getList, getLong, getLong, getLong, getProperties, getProperty, getShort, getShort, getShort, getString, getString, getStringArray, immutableSubset, isEmpty, sizeMethods inherited from interface org.apache.commons.configuration2.sync.SynchronizerSupport
getSynchronizer, lock, setSynchronizer, unlock
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Constructor Details
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XMLConfiguration
public XMLConfiguration()Creates a new instance ofXMLConfiguration. -
XMLConfiguration
Creates a new instance ofXMLConfigurationand copies the content of the passed in configuration into this object. Note that only the data of the passed in configuration will be copied. If, for instance, the other configuration is aXMLConfiguration, too, things like comments or processing instructions will be lost.- Parameters:
c- the configuration to copy- Since:
- 1.4
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Method Details
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createDocumentBuilder
Creates theDocumentBuilderto be used for loading files. This implementation checks whether a specificDocumentBuilderhas been set. If this is the case, this one is used. Otherwise a default builder is created. Depending on the value of the validating flag this builder will be a validating or a non validatingDocumentBuilder.- Returns:
- the
DocumentBuilderfor loading configuration files - Throws:
ParserConfigurationException- if an error occurs- Since:
- 1.2
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createTransformer
Creates and initializes the transformer used for save operations. This base implementation initializes all of the default settings like indentation mode and the DOCTYPE. Derived classes may overload this method if they have specific needs.- Returns:
- the transformer to use for a save operation
- Throws:
ConfigurationException- if an error occurs- Since:
- 1.3
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getDocument
Gets the XML document this configuration was loaded from. The return value is null if this configuration was not loaded from a XML document.- Returns:
- the XML document this configuration was loaded from
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getDocumentBuilder
Gets theDocumentBuilderobject that is used for loading documents. If no specific builder has been set, this method returns null.- Returns:
- the
DocumentBuilderfor loading new documents - Since:
- 1.2
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getEntityResolver
Gets the EntityResolver.- Returns:
- The EntityResolver.
- Since:
- 1.7
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getPublicID
Gets the public ID of the DOCTYPE declaration from the loaded XML document. This is null if no document has been loaded yet or if the document does not contain a DOCTYPE declaration with a public ID.- Returns:
- the public ID
- Since:
- 1.3
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getRootElementNameInternal
Gets the name of the root element. If this configuration was loaded from a XML document, the name of this document's root element is returned. Otherwise it is possible to set a name for the root element that will be used when this configuration is stored.- Overrides:
getRootElementNameInternalin classAbstractHierarchicalConfiguration<ImmutableNode>- Returns:
- the name of the root element
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getSystemID
Gets the system ID of the DOCTYPE declaration from the loaded XML document. This is null if no document has been loaded yet or if the document does not contain a DOCTYPE declaration with a system ID.- Returns:
- the system ID
- Since:
- 1.3
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initFileLocator
Passes the currentFileLocatorto this object. Note that thisFileLocatorobject is only temporarily valid for the following invocation ofread()orwrite(. Depending on the state of theFileHandlerand which of its methods was called, the object may not be fully initialized. For instance, if theFileHandler'sload(InputStream)method was called, no file information is available, and all methods of theFileLocatorwill return null. Stores the passed in locator for the upcoming IO operation.- Specified by:
initFileLocatorin interfaceFileLocatorAware- Parameters:
loc- the currentFileLocator
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isSchemaValidation
Returns the value of the schemaValidation flag.- Returns:
- the schemaValidation flag
- Since:
- 1.7
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isValidating
Returns the value of the validating flag.- Returns:
- the validating flag
- Since:
- 1.2
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read
Loads the configuration from the given input stream. This is analogous toread(Reader), but data is read from a stream. Note that this method will be called most time when reading an XML configuration source. By reading XML documents directly from an input stream, the file's encoding can be correctly dealt with.- Specified by:
readin interfaceInputStreamSupport- Parameters:
in- the input stream- Throws:
ConfigurationException- if an error occursIOException- if an IO error occurs
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read
Loads the configuration from the given reader. Note that theclear()method is not called, so the properties contained in the loaded file will be added to the current set of properties.- Specified by:
readin interfaceFileBased- Parameters:
in- the reader- Throws:
ConfigurationException- if an error occursIOException- if an IO error occurs
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setDocumentBuilder
Sets theDocumentBuilderobject to be used for loading documents. This method makes it possible to specify the exact document builder. So an application can create a builder, configure it for its special needs, and then pass it to this method.- Parameters:
documentBuilder- the document builder to be used; if undefined, a default builder will be used- Since:
- 1.2
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setEntityResolver
Sets a new EntityResolver. Setting this will cause RegisterEntityId to have no effect.- Parameters:
resolver- The EntityResolver to use.- Since:
- 1.7
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setPublicID
Sets the public ID of the DOCTYPE declaration. When this configuration is saved, a DOCTYPE declaration will be constructed that contains this public ID.- Parameters:
publicID- the public ID- Since:
- 1.3
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setRootElementName
Sets the name of the root element. This name is used when this configuration object is stored in an XML file. Note that setting the name of the root element works only if this configuration has been newly created. If the configuration was loaded from an XML file, the name cannot be changed and anUnsupportedOperationExceptionexception is thrown. Whether this configuration has been loaded from an XML document or not can be found out using thegetDocument()method.- Parameters:
name- the name of the root element
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setSchemaValidation
Sets the value of the schemaValidation flag. This flag determines whether DTD or Schema validation should be used. This flag is evaluated only if no customDocumentBuilderwas set. If set to true the XML document must contain a schemaLocation definition that provides resolvable hints to the required schemas.- Parameters:
schemaValidation- the validating flag- Since:
- 1.7
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setSystemID
Sets the system ID of the DOCTYPE declaration. When this configuration is saved, a DOCTYPE declaration will be constructed that contains this system ID.- Parameters:
systemID- the system ID- Since:
- 1.3
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setValidating
Sets the value of the validating flag. This flag determines whether DTD/Schema validation should be performed when loading XML documents. This flag is evaluated only if no customDocumentBuilderwas set.- Parameters:
validating- the validating flag- Since:
- 1.2
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validate
Validate the document against the Schema.- Throws:
ConfigurationException- if the validation fails.
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write
Saves the configuration to the specified writer.- Specified by:
writein interfaceFileBased- Parameters:
writer- the writer used to save the configuration- Throws:
ConfigurationException- if an error occursIOException- if an IO error occurs
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write
Saves the configuration to the specified writer.- Parameters:
writer- the writer used to save the configuration.transformer- How to transform this configuration.- Throws:
ConfigurationException- if an error occurs.- Since:
- 2.7.0
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