    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.configuration2.builder;
    018
    019import java.util.Collection;
    020import java.util.Collections;
    021import java.util.HashMap;
    022import java.util.Map;
    023
    024import org.apache.commons.configuration2.ConfigurationUtils;
    025import org.apache.commons.configuration2.ImmutableConfiguration;
    026import org.apache.commons.configuration2.Initializable;
    027import org.apache.commons.configuration2.beanutils.BeanDeclaration;
    028import org.apache.commons.configuration2.beanutils.BeanHelper;
    029import org.apache.commons.configuration2.beanutils.ConstructorArg;
    030import org.apache.commons.configuration2.event.Event;
    031import org.apache.commons.configuration2.event.EventListener;
    032import org.apache.commons.configuration2.event.EventListenerList;
    033import org.apache.commons.configuration2.event.EventListenerRegistrationData;
    034import org.apache.commons.configuration2.event.EventSource;
    035import org.apache.commons.configuration2.event.EventType;
    036import org.apache.commons.configuration2.ex.ConfigurationException;
    037import org.apache.commons.configuration2.ex.ConfigurationRuntimeException;
    038import org.apache.commons.configuration2.reloading.ReloadingController;
    039
    040/**
    041 * <p>
    042 * An implementation of the {@code ConfigurationBuilder} interface which is able to create different concrete
    043 * {@code ImmutableConfiguration} implementations based on reflection.
    044 * </p>
    045 * <p>
    046 * When constructing an instance of this class the concrete {@code ImmutableConfiguration} implementation class has to
    047 * be provided. Then properties for the new {@code ImmutableConfiguration} instance can be set. The first call to
    048 * {@code getConfiguration()} creates and initializes the new {@code ImmutableConfiguration} object. It is cached and
    049 * returned by subsequent calls. This cache - and also the initialization properties set so far - can be flushed by
    050 * calling one of the {@code reset()} methods. That way other {@code ImmutableConfiguration} instances with different
    051 * properties can be created.
    052 * </p>
    053 * <p>
    054 * If the newly created {@code ImmutableConfiguration} object implements the {@code Initializable} interface, its
    055 * {@code initialize()} method is called after all initialization properties have been set. This way a concrete
    056 * implementation class can perform arbitrary initialization steps.
    057 * </p>
    058 * <p>
    059 * There are multiple options for setting up a {@code BasicConfigurationBuilder} instance:
    060 * </p>
    061 * <ul>
    062 * <li>All initialization properties can be set in one or multiple calls of the {@code configure()} method. In each call
    063 * an arbitrary number of {@link BuilderParameters} objects can be passed. The API allows method chaining and is
    064 * intended to be used from Java code.</li>
    065 * <li>If builder instances are created by other means - for example using a dependency injection framework -, the fluent API
    066 * approach may not be suitable. For those use cases it is also possible to pass in all initialization parameters as a
    067 * map. The keys of the map have to match initialization properties of the {@code ImmutableConfiguration} object to be
    068 * created, the values are the corresponding property values. For instance, the key <em>throwExceptionOnMissing</em> in
    069 * the map will cause the method {@code setThrowExceptionOnMissing()} on the {@code ImmutableConfiguration} object to be
    070 * called with the corresponding value as parameter.</li>
    071 * </ul>
    072 * <p>
    073 * A builder instance can be constructed with an <em>allowFailOnInit</em> flag. If set to <strong>true</strong>,
    074 * exceptions during initialization of the configuration are ignored; in such a case an empty configuration object is
    075 * returned. A use case for this flag is a scenario in which a configuration is optional and created on demand the first
    076 * time configuration data is to be stored. Consider an application that stores user-specific configuration data in the
    077 * user's home directory: When started for the first time by a new user there is no configuration file; so it makes
    078 * sense to start with an empty configuration object. On application exit, settings can be stored in this object and
    079 * written to the associated file. Then they are available on next application start.
    080 * </p>
    081 * <p>
    082 * This class is thread-safe. Multiple threads can modify initialization properties and call {@code getConfiguration()}.
    083 * However, the intended use case is that the builder is configured by a single thread first. Then
    084 * {@code getConfiguration()} can be called concurrently, and it is guaranteed that always the same
    085 * {@code ImmutableConfiguration} instance is returned until the builder is reset.
    086 * </p>
    087 *
    088 * @param <T> the concrete type of {@code ImmutableConfiguration} objects created by this builder
    089 * @since 2.0
    090 */
    091public class BasicConfigurationBuilder<T extends ImmutableConfiguration> implements ConfigurationBuilder<T> {
    092    /**
    093     * Registers an event listener at an event source object.
    094     *
    095     * @param evSrc the event source
    096     * @param regData the registration data object
    097     * @param <E> the type of the event listener
    098     */
    099    private static <E extends Event> void registerListener(final EventSource evSrc, final EventListenerRegistrationData<E> regData) {
    100        evSrc.addEventListener(regData.getEventType(), regData.getListener());
    101    }
    102
    103    /**
    104     * Removes an event listener from an event source object.
    105     *
    106     * @param evSrc the event source
    107     * @param regData the registration data object
    108     * @param <E> the type of the event listener
    109     */
    110    private static <E extends Event> void removeListener(final EventSource evSrc, final EventListenerRegistrationData<E> regData) {
    111        evSrc.removeEventListener(regData.getEventType(), regData.getListener());
    112    }
    113
    114    /** The class of the objects produced by this builder instance. */
    115    private final Class<? extends T> resultClass;
    116
    117    /** An object managing the event listeners registered at this builder. */
    118    private final EventListenerList eventListeners;
    119
    120    /** A flag whether exceptions on initializing configurations are allowed. */
    121    private final boolean allowFailOnInit;
    122
    123    /** The map with current initialization parameters. */
    124    private Map<String, Object> parameters;
    125
    126    /** The current bean declaration. */
    127    private BeanDeclaration resultDeclaration;
    128
    129    /** The result object of this builder. */
    130    private volatile T result;
    131
    132    /**
    133     * Creates a new instance of {@code BasicConfigurationBuilder} and initializes it with the given result class. No
    134     * initialization properties are set.
    135     *
    136     * @param resCls the result class (must not be <strong>null</strong>)
    137     * @throws IllegalArgumentException if the result class is <strong>null</strong>
    138     */
    139    public BasicConfigurationBuilder(final Class<? extends T> resCls) {
    140        this(resCls, null);
    141    }
    142
    143    /**
    144     * Creates a new instance of {@code BasicConfigurationBuilder} and initializes it with the given result class and an
    145     * initial set of builder parameters. The <em>allowFailOnInit</em> flag is set to <strong>false</strong>.
    146     *
    147     * @param resCls the result class (must not be <strong>null</strong>)
    148     * @param params a map with initialization parameters
    149     * @throws IllegalArgumentException if the result class is <strong>null</strong>
    150     */
    151    public BasicConfigurationBuilder(final Class<? extends T> resCls, final Map<String, Object> params) {
    152        this(resCls, params, false);
    153    }
    154
    155    /**
    156     * Creates a new instance of {@code BasicConfigurationBuilder} and initializes it with the given result class, an
    157     * initial set of builder parameters, and the <em>allowFailOnInit</em> flag. The map with parameters may be <strong>null</strong>,
    158     * in this case no initialization parameters are set.
    159     *
    160     * @param resCls the result class (must not be <strong>null</strong>)
    161     * @param params a map with initialization parameters
    162     * @param allowFailOnInit a flag whether exceptions on initializing a newly created {@code ImmutableConfiguration}
    163     *        object are allowed
    164     * @throws IllegalArgumentException if the result class is <strong>null</strong>
    165     */
    166    public BasicConfigurationBuilder(final Class<? extends T> resCls, final Map<String, Object> params, final boolean allowFailOnInit) {
    167        if (resCls == null) {
    168            throw new IllegalArgumentException("Result class must not be null!");
    169        }
    170
    171        resultClass = resCls;
    172        this.allowFailOnInit = allowFailOnInit;
    173        eventListeners = new EventListenerList();
    174        updateParameters(params);
    175    }
    176
    177    /**
    178     * {@inheritDoc} This implementation also takes care that the event listener is added to the managed configuration
    179     * object.
    180     *
    181     * @throws IllegalArgumentException if the event type or the listener is <strong>null</strong>
    182     */
    183    @Override
    184    public <E extends Event> void addEventListener(final EventType<E> eventType, final EventListener<? super E> listener) {
    185        installEventListener(eventType, listener);
    186    }
    187
    188    /**
    189     * Adds the content of the given map to the already existing initialization parameters.
    190     *
    191     * @param params the map with additional initialization parameters; may be <strong>null</strong>, then this call has no effect
    192     * @return a reference to this builder for method chaining
    193     */
    194    public synchronized BasicConfigurationBuilder<T> addParameters(final Map<String, Object> params) {
    195        final Map<String, Object> newParams = new HashMap<>(getParameters());
    196        if (params != null) {
    197            newParams.putAll(params);
    198        }
    199        updateParameters(newParams);
    200        return this;
    201    }
    202
    203    /**
    204     * Checks whether the class of the result configuration is compatible with this builder's result class. This is done to
    205     * ensure that only objects of the expected result class are created.
    206     *
    207     * @param inst the result instance to be checked
    208     * @throws ConfigurationRuntimeException if an invalid result class is detected
    209     */
    210    private void checkResultInstance(final Object inst) {
    211        if (!getResultClass().isInstance(inst)) {
    212            throw new ConfigurationRuntimeException("Incompatible result object: " + inst);
    213        }
    214    }
    215
    216    /**
    217     * Appends the content of the specified {@code BuilderParameters} objects to the current initialization parameters.
    218     * Calling this method multiple times will create a union of the parameters provided.
    219     *
    220     * @param params an arbitrary number of objects with builder parameters
    221     * @return a reference to this builder for method chaining
    222     * @throws NullPointerException if a <strong>null</strong> array is passed
    223     */
    224    public BasicConfigurationBuilder<T> configure(final BuilderParameters... params) {
    225        final Map<String, Object> newParams = new HashMap<>();
    226        for (final BuilderParameters p : params) {
    227            newParams.putAll(p.getParameters());
    228            handleEventListenerProviders(p);
    229        }
    230        return setParameters(newParams);
    231    }
    232
    233    /**
    234     * Connects this builder with a {@code ReloadingController}. With this method support for reloading can be added to an
    235     * arbitrary builder object. Event listeners are registered at the reloading controller and this builder with connect
    236     * both objects:
    237     * <ul>
    238     * <li>When the reloading controller detects that a reload is required, the builder's {@link #resetResult()} method is
    239     * called; so the managed result object is invalidated.</li>
    240     * <li>When a new result object has been created the controller's reloading state is reset, so that new changes can be
    241     * detected again.</li>
    242     * </ul>
    243     *
    244     * @param controller the {@code ReloadingController} to connect to (must not be <strong>null</strong>)
    245     * @throws IllegalArgumentException if the controller is <strong>null</strong>
    246     */
    247    public final void connectToReloadingController(final ReloadingController controller) {
    248        if (controller == null) {
    249            throw new IllegalArgumentException("ReloadingController must not be null!");
    250        }
    251        ReloadingBuilderSupportListener.connect(this, controller);
    252    }
    253
    254    /**
    255     * Copies all {@code EventListener} objects registered at this builder to the specified target configuration builder.
    256     * This method is intended to be used by derived classes which support inheritance of their properties to other builder
    257     * objects.
    258     *
    259     * @param target the target configuration builder (must not be <strong>null</strong>)
    260     * @throws NullPointerException if the target builder is <strong>null</strong>
    261     */
    262    protected synchronized void copyEventListeners(final BasicConfigurationBuilder<?> target) {
    263        copyEventListeners(target, eventListeners);
    264    }
    265
    266    /**
    267     * Copies all event listeners in the specified list to the specified target configuration builder. This method is
    268     * intended to be used by derived classes which have to deal with managed configuration builders that need to be
    269     * initialized with event listeners.
    270     *
    271     * @param target the target configuration builder (must not be <strong>null</strong>)
    272     * @param listeners the event listeners to be copied over
    273     * @throws NullPointerException if the target builder is <strong>null</strong>
    274     */
    275    protected void copyEventListeners(final BasicConfigurationBuilder<?> target, final EventListenerList listeners) {
    276        target.eventListeners.addAll(listeners);
    277    }
    278
    279    /**
    280     * Creates a new, initialized result object. This method is called by {@code getConfiguration()} if no valid result
    281     * object exists. This base implementation performs two steps:
    282     * <ul>
    283     * <li>{@code createResultInstance()} is called to create a new, uninitialized result object.</li>
    284     * <li>{@code initResultInstance()} is called to process all initialization parameters.</li>
    285     * </ul>
    286     * It also evaluates the <em>allowFailOnInit</em> flag, i.e. if initialization causes an exception and this flag is set,
    287     * the exception is ignored, and the newly created, uninitialized configuration is returned. Note that this method is
    288     * called in a synchronized block.
    289     *
    290     * @return the newly created result object
    291     * @throws ConfigurationException if an error occurs
    292     */
    293    protected T createResult() throws ConfigurationException {
    294        final T resObj = createResultInstance();
    295
    296        try {
    297            initResultInstance(resObj);
    298        } catch (final ConfigurationException cex) {
    299            if (!isAllowFailOnInit()) {
    300                throw cex;
    301            }
    302        }
    303
    304        return resObj;
    305    }
    306
    307    /**
    308     * Creates a new {@code BeanDeclaration} which is used for creating new result objects dynamically. This implementation
    309     * creates a specialized {@code BeanDeclaration} object that is initialized from the given map of initialization
    310     * parameters. The {@code BeanDeclaration} must be initialized with the result class of this builder, otherwise
    311     * exceptions will be thrown when the result object is created. Note: This method is invoked in a synchronized block.
    312     *
    313     * @param params a snapshot of the current initialization parameters
    314     * @return the {@code BeanDeclaration} for creating result objects
    315     * @throws ConfigurationException if an error occurs
    316     */
    317    protected BeanDeclaration createResultDeclaration(final Map<String, Object> params) throws ConfigurationException {
    318        return new BeanDeclaration() {
    319            @Override
    320            public String getBeanClassName() {
    321                return getResultClass().getName();
    322            }
    323
    324            @Override
    325            public String getBeanFactoryName() {
    326                return null;
    327            }
    328
    329            @Override
    330            public Object getBeanFactoryParameter() {
    331                return null;
    332            }
    333
    334            @Override
    335            public Map<String, Object> getBeanProperties() {
    336                // the properties are equivalent to the parameters
    337                return params;
    338            }
    339
    340            @Override
    341            public Collection<ConstructorArg> getConstructorArgs() {
    342                // no constructor arguments
    343                return Collections.emptySet();
    344            }
    345
    346            @Override
    347            public Map<String, Object> getNestedBeanDeclarations() {
    348                // no nested beans
    349                return Collections.emptyMap();
    350            }
    351        };
    352    }
    353
    354    /**
    355     * Creates the new, uninitialized result object. This is the first step of the process of producing a result object for
    356     * this builder. This implementation uses the {@link BeanHelper} class to create a new object based on the
    357     * {@link BeanDeclaration} returned by {@link #getResultDeclaration()}. Note: This method is invoked in a synchronized
    358     * block.
    359     *
    360     * @return the newly created, yet uninitialized result object
    361     * @throws ConfigurationException if an exception occurs
    362     */
    363    protected T createResultInstance() throws ConfigurationException {
    364        final Object bean = fetchBeanHelper().createBean(getResultDeclaration());
    365        checkResultInstance(bean);
    366        return getResultClass().cast(bean);
    367    }
    368
    369    /**
    370     * Obtains the {@code BeanHelper} object to be used when dealing with bean declarations. This method checks whether this
    371     * builder was configured with a specific {@code BeanHelper} instance. If so, this instance is used. Otherwise, the
    372     * default {@code BeanHelper} is returned.
    373     *
    374     * @return the {@code BeanHelper} to be used
    375     */
    376    protected final BeanHelper fetchBeanHelper() {
    377        final BeanHelper helper = BasicBuilderParameters.fetchBeanHelper(getParameters());
    378        return helper != null ? helper : BeanHelper.INSTANCE;
    379    }
    380
    381    /**
    382     * Returns an {@code EventSource} for the current result object. If there is no current result or if it does not extend
    383     * {@code EventSource}, a dummy event source is returned.
    384     *
    385     * @return the {@code EventSource} for the current result object
    386     */
    387    private EventSource fetchEventSource() {
    388        return ConfigurationUtils.asEventSource(result, true);
    389    }
    390
    391    /**
    392     * Sends the specified builder event to all registered listeners.
    393     *
    394     * @param event the event to be fired
    395     */
    396    protected void fireBuilderEvent(final ConfigurationBuilderEvent event) {
    397        eventListeners.fire(event);
    398    }
    399
    400    /**
    401     * {@inheritDoc} This implementation creates the result configuration on first access. Later invocations return the same
    402     * object until this builder is reset. The double-check idiom for lazy initialization is used (Bloch, Effective Java,
    403     * item 71).
    404     */
    405    @Override
    406    public T getConfiguration() throws ConfigurationException {
    407        fireBuilderEvent(new ConfigurationBuilderEvent(this, ConfigurationBuilderEvent.CONFIGURATION_REQUEST));
    408
    409        T resObj = result;
    410        boolean created = false;
    411        if (resObj == null) {
    412            synchronized (this) {
    413                resObj = result;
    414                if (resObj == null) {
    415                    result = resObj = createResult();
    416                    created = true;
    417                }
    418            }
    419        }
    420
    421        if (created) {
    422            fireBuilderEvent(new ConfigurationBuilderResultCreatedEvent(this, ConfigurationBuilderResultCreatedEvent.RESULT_CREATED, resObj));
    423        }
    424        return resObj;
    425    }
    426
    427    /**
    428     * Gets a map with initialization parameters where all parameters starting with the reserved prefix have been
    429     * filtered out.
    430     *
    431     * @return the filtered parameters map
    432     */
    433    private Map<String, Object> getFilteredParameters() {
    434        final Map<String, Object> filteredMap = new HashMap<>(getParameters());
    435        filteredMap.keySet().removeIf(key -> key.startsWith(BuilderParameters.RESERVED_PARAMETER_PREFIX));
    436        return filteredMap;
    437    }
    438
    439    /**
    440     * Gets a (unmodifiable) map with the current initialization parameters set for this builder. The map is populated
    441     * with the parameters set using the various configuration options.
    442     *
    443     * @return a map with the current set of initialization parameters
    444     */
    445    protected final synchronized Map<String, Object> getParameters() {
    446        if (parameters != null) {
    447            return parameters;
    448        }
    449        return Collections.emptyMap();
    450    }
    451
    452    /**
    453     * Gets the result class of this builder. The objects produced by this builder have the class returned here.
    454     *
    455     * @return the result class of this builder
    456     */
    457    public Class<? extends T> getResultClass() {
    458        return resultClass;
    459    }
    460
    461    /**
    462     * Gets the {@code BeanDeclaration} that is used to create and initialize result objects. The declaration is created
    463     * on first access (by invoking {@link #createResultDeclaration(Map)}) based on the current initialization parameters.
    464     *
    465     * @return the {@code BeanDeclaration} for dynamically creating a result object
    466     * @throws ConfigurationException if an error occurs
    467     */
    468    protected final synchronized BeanDeclaration getResultDeclaration() throws ConfigurationException {
    469        if (resultDeclaration == null) {
    470            resultDeclaration = createResultDeclaration(getFilteredParameters());
    471        }
    472        return resultDeclaration;
    473    }
    474
    475    /**
    476     * Checks whether the specified parameters object implements the {@code EventListenerProvider} interface. If so, the
    477     * event listeners it provides are added to this builder.
    478     *
    479     * @param params the parameters object
    480     */
    481    private void handleEventListenerProviders(final BuilderParameters params) {
    482        if (params instanceof EventListenerProvider) {
    483            eventListeners.addAll(((EventListenerProvider) params).getListeners());
    484        }
    485    }
    486
    487    /**
    488     * Performs special initialization of the result object. This method is called after parameters have been set on a newly
    489     * created result instance. If supported by the result class, the {@code initialize()} method is now called.
    490     *
    491     * @param obj the newly created result object
    492     */
    493    private void handleInitializable(final T obj) {
    494        if (obj instanceof Initializable) {
    495            ((Initializable) obj).initialize();
    496        }
    497    }
    498
    499    /**
    500     * Initializes a newly created result object. This is the second step of the process of producing a result object for
    501     * this builder. This implementation uses the {@link BeanHelper} class to initialize the object's property based on the
    502     * {@link BeanDeclaration} returned by {@link #getResultDeclaration()}. Note: This method is invoked in a synchronized
    503     * block. This is required because internal state is accessed. Sub classes must not call this method without proper
    504     * synchronization.
    505     *
    506     * @param obj the object to be initialized
    507     * @throws ConfigurationException if an error occurs
    508     */
    509    protected void initResultInstance(final T obj) throws ConfigurationException {
    510        fetchBeanHelper().initBean(obj, getResultDeclaration());
    511        registerEventListeners(obj);
    512        handleInitializable(obj);
    513    }
    514
    515    /**
    516     * Adds the specified event listener to this object. This method is called by {@code addEventListener()}, it does the
    517     * actual listener registration. Because it is final it can be called by sub classes in the constructor if there is
    518     * already the need to register an event listener.
    519     *
    520     * @param eventType the event type object
    521     * @param listener the listener to be registered
    522     * @param <E> the event type
    523     */
    524    protected final <E extends Event> void installEventListener(final EventType<E> eventType, final EventListener<? super E> listener) {
    525        fetchEventSource().addEventListener(eventType, listener);
    526        eventListeners.addEventListener(eventType, listener);
    527    }
    528
    529    /**
    530     * Returns the <em>allowFailOnInit</em> flag. See the header comment for information about this flag.
    531     *
    532     * @return the <em>allowFailOnInit</em> flag
    533     */
    534    public boolean isAllowFailOnInit() {
    535        return allowFailOnInit;
    536    }
    537
    538    /**
    539     * Registers the available event listeners at the given object. This method is called for each result object created by
    540     * the builder.
    541     *
    542     * @param obj the object to initialize
    543     */
    544    private void registerEventListeners(final T obj) {
    545        final EventSource evSrc = ConfigurationUtils.asEventSource(obj, true);
    546        eventListeners.getRegistrations().forEach(regData -> registerListener(evSrc, regData));
    547    }
    548
    549    /**
    550     * {@inheritDoc} This implementation also takes care that the event listener is removed from the managed configuration
    551     * object.
    552     */
    553    @Override
    554    public <E extends Event> boolean removeEventListener(final EventType<E> eventType, final EventListener<? super E> listener) {
    555        fetchEventSource().removeEventListener(eventType, listener);
    556        return eventListeners.removeEventListener(eventType, listener);
    557    }
    558
    559    /**
    560     * Removes all available event listeners from the given result object. This method is called when the result of this
    561     * builder is reset. Then the old managed configuration should no longer generate events.
    562     *
    563     * @param obj the affected result object
    564     */
    565    private void removeEventListeners(final T obj) {
    566        final EventSource evSrc = ConfigurationUtils.asEventSource(obj, true);
    567        eventListeners.getRegistrations().forEach(regData -> removeListener(evSrc, regData));
    568    }
    569
    570    /**
    571     * Resets this builder. This is a convenience method which combines calls to {@link #resetResult()} and
    572     * {@link #resetParameters()}.
    573     */
    574    public synchronized void reset() {
    575        resetParameters();
    576        resetResult();
    577    }
    578
    579    /**
    580     * Removes all initialization parameters of this builder. This method can be called if this builder is to be reused for
    581     * creating result objects with a different configuration.
    582     */
    583    public void resetParameters() {
    584        setParameters(null);
    585    }
    586
    587    /**
    588     * Clears an existing result object. An invocation of this method causes a new {@code ImmutableConfiguration} object to
    589     * be created the next time {@link #getConfiguration()} is called.
    590     */
    591    public void resetResult() {
    592        final T oldResult;
    593        synchronized (this) {
    594            oldResult = result;
    595            result = null;
    596            resultDeclaration = null;
    597        }
    598
    599        if (oldResult != null) {
    600            removeEventListeners(oldResult);
    601        }
    602        fireBuilderEvent(new ConfigurationBuilderEvent(this, ConfigurationBuilderEvent.RESET));
    603    }
    604
    605    /**
    606     * Sets the initialization parameters of this builder. Already existing parameters are replaced by the content of the
    607     * given map.
    608     *
    609     * @param params the new initialization parameters of this builder; can be <strong>null</strong>, then all initialization
    610     *        parameters are removed
    611     * @return a reference to this builder for method chaining
    612     */
    613    public synchronized BasicConfigurationBuilder<T> setParameters(final Map<String, Object> params) {
    614        updateParameters(params);
    615        return this;
    616    }
    617
    618    /**
    619     * Replaces the current map with parameters by a new one.
    620     *
    621     * @param newParams the map with new parameters (may be <strong>null</strong>)
    622     */
    623    private void updateParameters(final Map<String, Object> newParams) {
    624        final Map<String, Object> map = new HashMap<>();
    625        if (newParams != null) {
    626            map.putAll(newParams);
    627        }
    628        parameters = Collections.unmodifiableMap(map);
    629    }
    630}