--- /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 :