com.github.datalking.io.PropertiesLoaderSupport Maven / Gradle / Ivy

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package com.github.datalking.io;

import com.github.datalking.common.DefaultPropertiesPersister;
import com.github.datalking.common.PropertiesPersister;
import com.github.datalking.util.CollectionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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

/**
 * @author yaoo on 5/28/18
 */
public abstract class PropertiesLoaderSupport {

    protected final Logger logger = LoggerFactory.getLogger(getClass());

    protected Properties[] localProperties;

    protected boolean localOverride = false;

    private Resource[] locations;

    private boolean ignoreResourceNotFound = false;

    private String fileEncoding;

    private PropertiesPersister propertiesPersister = new DefaultPropertiesPersister();

    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.
     * 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.
     * 
Can point to classic properties files or to XML files
     * that follow JDK 1.5's properties XML format.
     * 
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.
     * 
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.
     * 
"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.
     * 
Default is none, using the {@code java.util.Properties}
     * default encoding.
     * Only applies to classic properties files, not to XML files.
     */
    public void setFileEncoding(String encoding) {
        this.fileEncoding = encoding;
    }

    /**
     * Set the PropertiesPersister to use for parsing properties files.
     * The default is 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
     */
    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);
                }
                PropertiesLoaderUtils.fillProperties(
                        props,
                        new EncodedResource(location, this.fileEncoding),
                        this.propertiesPersister);
            }
        }
    }

}