BasicBuilderParameters.java
/*
* 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.commons.configuration2.builder;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.configuration2.ConfigurationDecoder;
import org.apache.commons.configuration2.beanutils.BeanHelper;
import org.apache.commons.configuration2.convert.ConversionHandler;
import org.apache.commons.configuration2.convert.ListDelimiterHandler;
import org.apache.commons.configuration2.interpol.ConfigurationInterpolator;
import org.apache.commons.configuration2.interpol.InterpolatorSpecification;
import org.apache.commons.configuration2.interpol.Lookup;
import org.apache.commons.configuration2.io.ConfigurationLogger;
import org.apache.commons.configuration2.sync.Synchronizer;
/**
* <p>
* An implementation of {@code BuilderParameters} which handles the parameters of a {@link ConfigurationBuilder} common
* to all concrete {@code Configuration} implementations.
* </p>
* <p>
* This class provides methods for setting standard properties supported by the {@code AbstractConfiguration} base
* class. A fluent interface can be used to set property values.
* </p>
* <p>
* This class is not thread-safe. It is intended that an instance is constructed and initialized by a single thread
* during configuration of a {@code ConfigurationBuilder}.
* </p>
*
* @since 2.0
*/
public class BasicBuilderParameters implements Cloneable, BuilderParameters, BasicBuilderProperties<BasicBuilderParameters> {
/** The key of the <em>throwExceptionOnMissing</em> property. */
private static final String PROP_THROW_EXCEPTION_ON_MISSING = "throwExceptionOnMissing";
/** The key of the <em>listDelimiterHandler</em> property. */
private static final String PROP_LIST_DELIMITER_HANDLER = "listDelimiterHandler";
/** The key of the <em>logger</em> property. */
private static final String PROP_LOGGER = "logger";
/** The key for the <em>interpolator</em> property. */
private static final String PROP_INTERPOLATOR = "interpolator";
/** The key for the <em>prefixLookups</em> property. */
private static final String PROP_PREFIX_LOOKUPS = "prefixLookups";
/** The key for the <em>defaultLookups</em> property. */
private static final String PROP_DEFAULT_LOOKUPS = "defaultLookups";
/** The key for the <em>parentInterpolator</em> property. */
private static final String PROP_PARENT_INTERPOLATOR = "parentInterpolator";
/** The key for the <em>synchronizer</em> property. */
private static final String PROP_SYNCHRONIZER = "synchronizer";
/** The key for the <em>conversionHandler</em> property. */
private static final String PROP_CONVERSION_HANDLER = "conversionHandler";
/** The key for the <em>configurationDecoder</em> property. */
private static final String PROP_CONFIGURATION_DECODER = "configurationDecoder";
/** The key for the {@code BeanHelper}. */
private static final String PROP_BEAN_HELPER = RESERVED_PARAMETER_PREFIX + "BeanHelper";
/**
* Checks whether a map with parameters is present. Throws an exception if not.
*
* @param params the map with parameters to check
* @throws IllegalArgumentException if the map is <b>null</b>
*/
private static void checkParameters(final Map<String, Object> params) {
if (params == null) {
throw new IllegalArgumentException("Parameters map must not be null!");
}
}
/**
* Creates defensive copies for collection structures when constructing the map with parameters. It should not be
* possible to modify this object's internal state when having access to the parameters map.
*
* @param params the map with parameters to be passed to the caller
*/
private static void createDefensiveCopies(final HashMap<String, Object> params) {
final Map<String, ? extends Lookup> prefixLookups = fetchPrefixLookups(params);
if (prefixLookups != null) {
params.put(PROP_PREFIX_LOOKUPS, new HashMap<>(prefixLookups));
}
final Collection<? extends Lookup> defLookups = fetchDefaultLookups(params);
if (defLookups != null) {
params.put(PROP_DEFAULT_LOOKUPS, new ArrayList<>(defLookups));
}
}
/**
* Tests whether the passed in map with parameters contains a valid collection with default lookups. This method works
* like {@link #fetchAndCheckPrefixLookups(Map)}, but tests the default lookups collection.
*
* @param params the map with parameters
* @return the collection with default lookups (may be <b>null</b>)
* @throws IllegalArgumentException if invalid data is found
*/
private static Collection<? extends Lookup> fetchAndCheckDefaultLookups(final Map<String, Object> params) {
final Collection<?> col = fetchParameter(params, PROP_DEFAULT_LOOKUPS, Collection.class);
if (col == null) {
return null;
}
if (col.stream().noneMatch(Lookup.class::isInstance)) {
throw new IllegalArgumentException("Collection with default lookups contains invalid data: " + col);
}
return fetchDefaultLookups(params);
}
/**
* Tests whether the passed in map with parameters contains a map with prefix lookups. This method is used if the
* parameters map is from an insecure source and we cannot be sure that it contains valid data. Therefore, we have to
* map that the key for the prefix lookups actually points to a map containing keys and values of expected data types.
*
* @param params the parameters map
* @return the obtained map with prefix lookups
* @throws IllegalArgumentException if the map contains invalid data
*/
private static Map<String, ? extends Lookup> fetchAndCheckPrefixLookups(final Map<String, Object> params) {
final Map<?, ?> prefixes = fetchParameter(params, PROP_PREFIX_LOOKUPS, Map.class);
if (prefixes == null) {
return null;
}
prefixes.forEach((k, v) -> {
if (!(k instanceof String) || !(v instanceof Lookup)) {
throw new IllegalArgumentException("Map with prefix lookups contains invalid data: " + prefixes);
}
});
return fetchPrefixLookups(params);
}
/**
* Obtains the {@code BeanHelper} object from the specified map with parameters. This method can be used to obtain an
* instance from a parameters map that has been set via the {@code setBeanHelper()} method. If no such instance is
* found, result is <b>null</b>.
*
* @param params the map with parameters (must not be <b>null</b>)
* @return the {@code BeanHelper} stored in this map or <b>null</b>
* @throws IllegalArgumentException if the map is <b>null</b>
*/
public static BeanHelper fetchBeanHelper(final Map<String, Object> params) {
checkParameters(params);
return (BeanHelper) params.get(PROP_BEAN_HELPER);
}
/**
* Obtains the collection with default lookups from the parameters map.
*
* @param params the map with parameters
* @return the collection with default lookups (may be <b>null</b>)
*/
private static Collection<? extends Lookup> fetchDefaultLookups(final Map<String, Object> params) {
// This is safe to cast because we either have full control over the map
// and thus know the types of the contained values or have checked
// the content before
@SuppressWarnings("unchecked")
final Collection<? extends Lookup> defLookups = (Collection<? extends Lookup>) params.get(PROP_DEFAULT_LOOKUPS);
return defLookups;
}
/**
* Obtains a specification for a {@link ConfigurationInterpolator} from the specified map with parameters. All
* properties related to interpolation are evaluated and added to the specification object.
*
* @param params the map with parameters (must not be <b>null</b>)
* @return an {@code InterpolatorSpecification} object constructed with data from the map
* @throws IllegalArgumentException if the map is <b>null</b> or contains invalid data
*/
public static InterpolatorSpecification fetchInterpolatorSpecification(final Map<String, Object> params) {
checkParameters(params);
return new InterpolatorSpecification.Builder().withInterpolator(fetchParameter(params, PROP_INTERPOLATOR, ConfigurationInterpolator.class))
.withParentInterpolator(fetchParameter(params, PROP_PARENT_INTERPOLATOR, ConfigurationInterpolator.class))
.withPrefixLookups(fetchAndCheckPrefixLookups(params)).withDefaultLookups(fetchAndCheckDefaultLookups(params)).create();
}
/**
* Obtains a parameter from a map and performs a type check.
*
* @param params the map with parameters
* @param key the key of the parameter
* @param expClass the expected class of the parameter value
* @param <T> the parameter type
* @return the value of the parameter in the correct data type
* @throws IllegalArgumentException if the parameter is not of the expected type
*/
private static <T> T fetchParameter(final Map<String, Object> params, final String key, final Class<T> expClass) {
final Object value = params.get(key);
if (value == null) {
return null;
}
if (!expClass.isInstance(value)) {
throw new IllegalArgumentException(String.format("Parameter %s is not of type %s!", key, expClass.getSimpleName()));
}
return expClass.cast(value);
}
/**
* Obtains the map with prefix lookups from the parameters map.
*
* @param params the map with parameters
* @return the map with prefix lookups (may be <b>null</b>)
*/
private static Map<String, ? extends Lookup> fetchPrefixLookups(final Map<String, Object> params) {
// This is safe to cast because we either have full control over the map
// and thus know the types of the contained values or have checked
// the content before
@SuppressWarnings("unchecked")
final Map<String, ? extends Lookup> prefixLookups = (Map<String, ? extends Lookup>) params.get(PROP_PREFIX_LOOKUPS);
return prefixLookups;
}
/** The map for storing the current property values. */
private Map<String, Object> properties;
/**
* Creates a new instance of {@code BasicBuilderParameters}.
*/
public BasicBuilderParameters() {
properties = new HashMap<>();
}
/**
* Clones this object. This is useful because multiple builder instances may use a similar set of parameters. However,
* single instances of parameter objects must not assigned to multiple builders. Therefore, cloning a parameters object
* provides a solution for this use case. This method creates a new parameters object with the same content as this one.
* The internal map storing the parameter values is cloned, too, also collection structures contained in this map.
* However, no a full deep clone operation is performed. Objects like a {@code ConfigurationInterpolator} or
* {@code Lookup}s are shared between this and the newly created instance.
*
* @return a clone of this object
*/
@Override
public BasicBuilderParameters clone() {
try {
final BasicBuilderParameters copy = (BasicBuilderParameters) super.clone();
copy.properties = getParameters();
return copy;
} catch (final CloneNotSupportedException cnex) {
// should not happen
throw new AssertionError(cnex);
}
}
/**
* Copies a number of properties from the given map into this object. Properties are only copied if they are defined in
* the source map.
*
* @param source the source map
* @param keys the keys to be copied
*/
protected void copyPropertiesFrom(final Map<String, ?> source, final String... keys) {
for (final String key : keys) {
final Object value = source.get(key);
if (value != null) {
storeProperty(key, value);
}
}
}
/**
* Obtains the value of the specified property from the internal map. This method can be used by derived classes if a
* specific property is to be accessed. If the given key is not found, result is <b>null</b>.
*
* @param key the key of the property in question
* @return the value of the property with this key or <b>null</b>
*/
protected Object fetchProperty(final String key) {
return properties.get(key);
}
/**
* {@inheritDoc} This implementation returns a copy of the internal parameters map with the values set so far.
* Collection structures (e.g. for lookup objects) are stored as defensive copies, so the original data cannot be
* modified.
*/
@Override
public Map<String, Object> getParameters() {
final HashMap<String, Object> result = new HashMap<>(properties);
if (result.containsKey(PROP_INTERPOLATOR)) {
// A custom ConfigurationInterpolator overrides lookups
result.remove(PROP_PREFIX_LOOKUPS);
result.remove(PROP_DEFAULT_LOOKUPS);
result.remove(PROP_PARENT_INTERPOLATOR);
}
createDefensiveCopies(result);
return result;
}
/**
* Inherits properties from the specified map. This can be used for instance to reuse parameters from one builder in
* another builder - also in parent-child relations in which a parent builder creates child builders. The purpose of
* this method is to let a concrete implementation decide which properties can be inherited. Because parameters are
* basically organized as a map it would be possible to simply copy over all properties from the source object. However,
* this is not appropriate in all cases. For instance, some properties - like a {@code ConfigurationInterpolator} - are
* tightly connected to a configuration and cannot be reused in a different context. For other properties, e.g. a file
* name, it does not make sense to copy it. Therefore, an implementation has to be explicit in the properties it wants
* to take over.
*
* @param source the source properties to inherit from
* @throws IllegalArgumentException if the source map is <b>null</b>
*/
public void inheritFrom(final Map<String, ?> source) {
if (source == null) {
throw new IllegalArgumentException("Source properties must not be null!");
}
copyPropertiesFrom(source, PROP_BEAN_HELPER, PROP_CONFIGURATION_DECODER, PROP_CONVERSION_HANDLER, PROP_LIST_DELIMITER_HANDLER, PROP_LOGGER,
PROP_SYNCHRONIZER, PROP_THROW_EXCEPTION_ON_MISSING);
}
/**
* Merges this object with the given parameters object. This method adds all property values defined by the passed in
* parameters object to the internal storage which are not already in. So properties already defined in this object take
* precedence. Property names starting with the reserved parameter prefix are ignored.
*
* @param p the object whose properties should be merged (must not be <b>null</b>)
* @throws IllegalArgumentException if the passed in object is <b>null</b>
*/
public void merge(final BuilderParameters p) {
if (p == null) {
throw new IllegalArgumentException("Parameters to merge must not be null!");
}
p.getParameters().forEach((k, v) -> {
if (!properties.containsKey(k) && !k.startsWith(RESERVED_PARAMETER_PREFIX)) {
storeProperty(k, v);
}
});
}
/**
* {@inheritDoc} This implementation stores the passed in {@code BeanHelper} object in the internal parameters map, but
* uses a reserved key, so that it is not used for the initialization of properties of the managed configuration object.
* The {@code fetchBeanHelper()} method can be used to obtain the {@code BeanHelper} instance from a parameters map.
*/
@Override
public BasicBuilderParameters setBeanHelper(final BeanHelper beanHelper) {
return setProperty(PROP_BEAN_HELPER, beanHelper);
}
/**
* {@inheritDoc} This implementation stores the passed in {@code ConfigurationDecoder} object in the internal parameters
* map.
*/
@Override
public BasicBuilderParameters setConfigurationDecoder(final ConfigurationDecoder decoder) {
return setProperty(PROP_CONFIGURATION_DECODER, decoder);
}
/**
* {@inheritDoc} This implementation stores the passed in {@code ConversionHandler} object in the internal parameters
* map.
*/
@Override
public BasicBuilderParameters setConversionHandler(final ConversionHandler handler) {
return setProperty(PROP_CONVERSION_HANDLER, handler);
}
/**
* {@inheritDoc} A defensive copy of the passed in collection is created. A <b>null</b> argument causes all default
* lookups to be removed from the internal parameters map.
*/
@Override
public BasicBuilderParameters setDefaultLookups(final Collection<? extends Lookup> lookups) {
if (lookups == null) {
properties.remove(PROP_DEFAULT_LOOKUPS);
return this;
}
return setProperty(PROP_DEFAULT_LOOKUPS, new ArrayList<>(lookups));
}
/**
* {@inheritDoc} The passed in {@code ConfigurationInterpolator} is set without modifications.
*/
@Override
public BasicBuilderParameters setInterpolator(final ConfigurationInterpolator ci) {
return setProperty(PROP_INTERPOLATOR, ci);
}
/**
* Sets the value of the <em>listDelimiterHandler</em> property. This property defines the object responsible for
* dealing with list delimiter and escaping characters. Note:
* {@link org.apache.commons.configuration2.AbstractConfiguration AbstractConfiguration} does not allow setting this
* property to <b>null</b>. If the default {@code ListDelimiterHandler} is to be used, do not call this method.
*
* @param handler the {@code ListDelimiterHandler}
* @return a reference to this object for method chaining
*/
@Override
public BasicBuilderParameters setListDelimiterHandler(final ListDelimiterHandler handler) {
return setProperty(PROP_LIST_DELIMITER_HANDLER, handler);
}
/**
* Sets the <em>logger</em> property. With this property a concrete {@code Log} object can be set for the configuration.
* Thus logging behavior can be controlled.
*
* @param log the {@code Log} for the configuration produced by this builder
* @return a reference to this object for method chaining
*/
@Override
public BasicBuilderParameters setLogger(final ConfigurationLogger log) {
return setProperty(PROP_LOGGER, log);
}
/**
* {@inheritDoc} This implementation stores the passed in {@code ConfigurationInterpolator} object in the internal
* parameters map.
*/
@Override
public BasicBuilderParameters setParentInterpolator(final ConfigurationInterpolator parent) {
return setProperty(PROP_PARENT_INTERPOLATOR, parent);
}
/**
* {@inheritDoc} A defensive copy of the passed in map is created. A <b>null</b> argument causes all prefix lookups to
* be removed from the internal parameters map.
*/
@Override
public BasicBuilderParameters setPrefixLookups(final Map<String, ? extends Lookup> lookups) {
if (lookups == null) {
properties.remove(PROP_PREFIX_LOOKUPS);
return this;
}
return setProperty(PROP_PREFIX_LOOKUPS, new HashMap<>(lookups));
}
/**
* Helper method for setting a property value.
*
* @param key the key of the property
* @param value the value of the property
* @return a reference to this object
*/
private BasicBuilderParameters setProperty(final String key, final Object value) {
storeProperty(key, value);
return this;
}
/**
* {@inheritDoc} This implementation stores the passed in {@code Synchronizer} object in the internal parameters map.
*/
@Override
public BasicBuilderParameters setSynchronizer(final Synchronizer sync) {
return setProperty(PROP_SYNCHRONIZER, sync);
}
/**
* Sets the value of the <em>throwExceptionOnMissing</em> property. This property controls the configuration's behavior
* if missing properties are queried: a value of <b>true</b> causes the configuration to throw an exception, for a value
* of <b>false</b> it will return <b>null</b> values. (Note: Methods returning a primitive data type will always throw
* an exception if the property is not defined.)
*
* @param b the value of the property
* @return a reference to this object for method chaining
*/
@Override
public BasicBuilderParameters setThrowExceptionOnMissing(final boolean b) {
return setProperty(PROP_THROW_EXCEPTION_ON_MISSING, Boolean.valueOf(b));
}
/**
* Sets a property for this parameters object. Properties are stored in an internal map. With this method a new entry
* can be added to this map. If the value is <b>null</b>, the key is removed from the internal map. This method can be
* used by sub classes which also store properties in a map.
*
* @param key the key of the property
* @param value the value of the property
*/
protected void storeProperty(final String key, final Object value) {
if (value == null) {
properties.remove(key);
} else {
properties.put(key, value);
}
}
}