Mercurial > dive4elements > river
diff flys-artifacts/src/main/java/de/intevation/flys/exports/AbstractExporter.java @ 391:5d6988836f01
Added an exporter to export the computed data of a duration curve.
flys-artifacts/trunk@1814 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author | Ingo Weinzierl <ingo.weinzierl@intevation.de> |
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date | Tue, 03 May 2011 17:37:56 +0000 |
parents | |
children | 046bd86ae41d |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/flys-artifacts/src/main/java/de/intevation/flys/exports/AbstractExporter.java Tue May 03 17:37:56 2011 +0000 @@ -0,0 +1,167 @@ +package de.intevation.flys.exports; + +import java.io.IOException; +import java.io.OutputStream; +import java.io.OutputStreamWriter; + +import org.w3c.dom.Document; + +import org.apache.log4j.Logger; + +import au.com.bytecode.opencsv.CSVWriter; + +import de.intevation.artifacts.Artifact; +import de.intevation.artifacts.CallContext; + + +/** + * An abstract exporter that implements some basic methods for exporting data of + * artifacts. + * + * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a> + */ +public abstract class AbstractExporter implements OutGenerator { + + /** The logger used in this exporter.*/ + private static Logger logger = Logger.getLogger(AbstractExporter.class); + + + /** The name of the CSV facet which triggers the CSV creation.*/ + public static final String FACET_CSV = "csv"; + + /** The default charset for the CSV export.*/ + public static final String DEFAULT_CSV_CHARSET = "UTF-8"; + + /** The default separator for the CSV export.*/ + public static final char DEFAULT_CSV_SEPARATOR = ','; + + + /** The document of the incoming out() request.*/ + protected Document request; + + /** The output stream where the data should be written to.*/ + protected OutputStream out; + + /** The CallContext object.*/ + protected CallContext context; + + /** The selected facet.*/ + protected String facet; + + + /** + * Concrete subclasses need to use this method to write their special data + * objects into the CSV document. + * + * @param writer The CSVWriter. + */ + protected abstract void writeCSVData(CSVWriter writer); + + + /** + * This method enables concrete subclasses to collected its own special + * data. + * + * @param artifacts The artifact that stores the data that has to be + * exported. + */ + protected abstract void addData(Artifact artifact); + + + public void init(Document request, OutputStream out, CallContext context) { + logger.debug("AbstractExporter.init"); + + this.request = request; + this.out = out; + this.context = context; + } + + + /** + * This doOut() just collects the data of multiple artifacts. Therefore, it + * makes use of the addData() method which enables concrete subclasses to + * store its data on its own. The real output creation takes place in the + * concrete generate() methods. + * + * @param artifact The artifact. + * @param facet The facet to add - NOTE: the facet needs to fit to the first + * facet inserted into this exporter. Otherwise this artifact/facet is + * skipped. + * @param attr The attr document. + */ + public void doOut(Artifact artifact, String facet, Document attr) { + logger.debug("AbstractExporter.doOut: " + facet); + + if (!isFacetValid(facet)) { + logger.warn("Facet '" + facet + "' not valid. No output created!"); + return; + } + + addData(artifact); + } + + + /** + * Generates an export based on a specified facet. + */ + public void generate() + throws IOException + { + logger.debug("AbstractExporter.generate"); + + if (facet != null && facet.equals(FACET_CSV)) { + generateCSV(); + } + else { + throw new IOException("invalid facet for exporter."); + } + } + + + /** + * Determines if the desired facet is valid for this exporter. If no facet + * is currently set, <i>facet</i> is set. + * + * @param facet The desired facet. + * + * @return true, if <i>facet</i> is valid, otherwise false. + */ + protected boolean isFacetValid(String facet) { + logger.debug("AbstractExporter.isFacetValid"); + + if (facet == null || facet.length() == 0) { + return false; + } + else if (this.facet == null || this.facet.length() == 0) { + logger.debug("Set the facet of this export: " + facet); + this.facet = facet; + + return true; + } + else { + return this.facet.equals(facet); + } + } + + + /** + * This method starts CSV creation. It makes use of writeCSVData() which has + * to be implemented by concrete subclasses. + */ + protected void generateCSV() + throws IOException + { + logger.info("AbstractExporter.generateCSV"); + + CSVWriter writer = new CSVWriter( + new OutputStreamWriter( + out, + DEFAULT_CSV_CHARSET), + DEFAULT_CSV_SEPARATOR); + + writeCSVData(writer); + + writer.close(); + } +} +// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :