util:properties

/*
 * Copyright 2002-2013 the original author or authors.
 *
 * 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 org.springframework.beans.factory.config;

import java.io.IOException;
import java.util.Properties;

import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.core.io.support.PropertiesLoaderSupport;

/**
 * Allows for making a properties file from a classpath location available
 * as Properties instance in a bean factory. Can be used to populate
 * any bean property of type Properties via a bean reference.
 *
 * <p>Supports loading from a properties file and/or setting local properties
 * on this FactoryBean. The created Properties instance will be merged from
 * loaded and local values. If neither a location nor local properties are set,
 * an exception will be thrown on initialization.
 *
 * <p>Can create a singleton or a new object on each request.
 * Default is a singleton.
 *
 * @author Juergen Hoeller
 * @see #setLocation
 * @see #setProperties
 * @see #setLocalOverride
 * @see java.util.Properties
 */
public class PropertiesFactoryBean extends PropertiesLoaderSupport
        implements FactoryBean<Properties>, InitializingBean {

    private boolean singleton = true;

    private Properties singletonInstance;


    /**
     * Set whether a shared ‘singleton‘ Properties instance should be
     * created, or rather a new Properties instance on each request.
     * <p>Default is "true" (a shared singleton).
     */
    public final void setSingleton(boolean singleton) {
        this.singleton = singleton;
    }

    @Override
    public final boolean isSingleton() {
        return this.singleton;
    }


    @Override
    public final void afterPropertiesSet() throws IOException {
        if (this.singleton) {
            this.singletonInstance = createProperties();
        }
    }

    @Override
    public final Properties getObject() throws IOException {
        if (this.singleton) {
            return this.singletonInstance;
        }
        else {
            return createProperties();
        }
    }

    @Override
    public Class<Properties> getObjectType() {
        return Properties.class;
    }


    /**
     * Template method that subclasses may override to construct the object
     * returned by this factory. The default implementation returns the
     * plain merged Properties instance.
     * <p>Invoked on initialization of this FactoryBean in case of a
     * shared singleton; else, on each {@link #getObject()} call.
     * @return the object returned by this factory
     * @throws IOException if an exception occured during properties loading
     * @see #mergeProperties()
     */
    protected Properties createProperties() throws IOException {
        return mergeProperties();
    }

}

/*
 * Copyright 2002-2014 the original author or authors.
 *
 * 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 org.springframework.core.io.support;

import java.io.IOException;
import java.util.Properties;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.core.io.Resource;
import org.springframework.util.CollectionUtils;
import org.springframework.util.DefaultPropertiesPersister;
import org.springframework.util.PropertiesPersister;

/**
 * Base class for JavaBean-style components that need to load properties
 * from one or more resources. Supports local properties as well, with
 * configurable overriding.
 *
 * @author Juergen Hoeller
 * @since 1.2.2
 */
public abstract class PropertiesLoaderSupport {

    /** Logger available to subclasses */
    protected final Log logger = LogFactory.getLog(getClass());

    protected Properties[] localProperties;

    protected boolean localOverride = false;

    private Resource[] locations;

    private boolean ignoreResourceNotFound = false;

    private String fileEncoding;

    private PropertiesPersister propertiesPersister = new DefaultPropertiesPersister();


    /**
     * Set local properties, e.g. via the "props" tag in XML bean definitions.
     * These can be considered defaults, to be overridden by properties
     * loaded from files.
     */
    public void setProperties(Properties properties) {
        this.localProperties = new Properties[] {properties};
    }

    /**
     * Set local properties, e.g. via the "props" tag in XML bean definitions,
     * allowing for merging multiple properties sets into one.
     */
    public void setPropertiesArray(Properties... propertiesArray) {
        this.localProperties = propertiesArray;
    }

    /**
     * Set a location of a properties file to be loaded.
     * <p>Can point to a classic properties file or to an XML file
     * that follows JDK 1.5‘s properties XML format.
     */
    public void setLocation(Resource location) {
        this.locations = new Resource[] {location};
    }

    /**
     * Set locations of properties files to be loaded.
     * <p>Can point to classic properties files or to XML files
     * that follow JDK 1.5‘s properties XML format.
     * <p>Note: Properties defined in later files will override
     * properties defined earlier files, in case of overlapping keys.
     * Hence, make sure that the most specific files are the last
     * ones in the given list of locations.
     */
    public void setLocations(Resource... locations) {
        this.locations = locations;
    }

    /**
     * Set whether local properties override properties from files.
     * <p>Default is "false": Properties from files override local defaults.
     * Can be switched to "true" to let local properties override defaults
     * from files.
     */
    public void setLocalOverride(boolean localOverride) {
        this.localOverride = localOverride;
    }

    /**
     * Set if failure to find the property resource should be ignored.
     * <p>"true" is appropriate if the properties file is completely optional.
     * Default is "false".
     */
    public void setIgnoreResourceNotFound(boolean ignoreResourceNotFound) {
        this.ignoreResourceNotFound = ignoreResourceNotFound;
    }

    /**
     * Set the encoding to use for parsing properties files.
     * <p>Default is none, using the {@code java.util.Properties}
     * default encoding.
     * <p>Only applies to classic properties files, not to XML files.
     * @see org.springframework.util.PropertiesPersister#load
     */
    public void setFileEncoding(String encoding) {
        this.fileEncoding = encoding;
    }

    /**
     * Set the PropertiesPersister to use for parsing properties files.
     * The default is DefaultPropertiesPersister.
     * @see org.springframework.util.DefaultPropertiesPersister
     */
    public void setPropertiesPersister(PropertiesPersister propertiesPersister) {
        this.propertiesPersister =
                (propertiesPersister != null ? propertiesPersister : new DefaultPropertiesPersister());
    }


    /**
     * Return a merged Properties instance containing both the
     * loaded properties and properties set on this FactoryBean.
     */
    protected Properties mergeProperties() throws IOException {
        Properties result = new Properties();

        if (this.localOverride) {
            // Load properties from file upfront, to let local properties override.
            loadProperties(result);
        }

        if (this.localProperties != null) {
            for (Properties localProp : this.localProperties) {
                CollectionUtils.mergePropertiesIntoMap(localProp, result);
            }
        }

        if (!this.localOverride) {
            // Load properties from file afterwards, to let those properties override.
            loadProperties(result);
        }

        return result;
    }

    /**
     * Load properties into the given instance.
     * @param props the Properties instance to load into
     * @throws IOException in case of I/O errors
     * @see #setLocations
     */
    protected void loadProperties(Properties props) throws IOException {
        if (this.locations != null) {
            for (Resource location : this.locations) {
                if (logger.isInfoEnabled()) {
                    logger.info("Loading properties file from " + location);
                }
                try {
                    PropertiesLoaderUtils.fillProperties(
                            props, new EncodedResource(location, this.fileEncoding), this.propertiesPersister);
                }
                catch (IOException ex) {
                    if (this.ignoreResourceNotFound) {
                        if (logger.isWarnEnabled()) {
                            logger.warn("Could not load properties from " + location + ": " + ex.getMessage());
                        }
                    }
                    else {
                        throw ex;
                    }
                }
            }
        }
    }

}