Mercurial > dive4elements > framework
view artifact-database/src/main/java/de/intevation/artifactdatabase/ProxyArtifact.java @ 218:70cbbe144931
Added a describe() method for ArtifactCollections.
artifacts/trunk@1558 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author | Ingo Weinzierl <ingo.weinzierl@intevation.de> |
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date | Thu, 24 Mar 2011 15:48:26 +0000 |
parents | 933bbc9fc11f |
children |
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/* * Copyright (c) 2010 by Intevation GmbH * * This program is free software under the LGPL (>=v2.1) * Read the file LGPL.txt coming with the software for details * or visit http://www.gnu.org/licenses/ if it does not exist. */ package de.intevation.artifactdatabase; import de.intevation.artifacts.Artifact; import de.intevation.artifacts.CallContext; import java.io.IOException; import java.io.OutputStream; import org.apache.log4j.Logger; import org.w3c.dom.Document; /** * The proxy artifact is a wrapper around another artifact. It simply forwards * the interface calls to this underlaying artifact. * The reason for using proxy artifacts is enable the workflow to exchange * artifacts at any time by something else without losing the concrete * artifact. From the outside it always looks like there is only one * distinct artifact.<br> * * An inner artifact is able to replace itself by indirectly hand over * the replacement via the call context to the proxy artifact.<br> * To do so the proxied artifact has to call * <code>callContext.getContextValue(EPLACE_PROXY, replacement);</code>. * After the current call (describe, feed, advance and out) of the proxied * artifact is finished the proxy artifact replaces the former proxied artifact * with the replacement. * * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a> */ public class ProxyArtifact extends DefaultArtifact { /** * Key to signal that the proxied artifact should be replaced. */ public static final Object REPLACE_PROXY = new Object(); private static Logger logger = Logger.getLogger(ProxyArtifact.class); /** * The proxied artifact. */ protected Artifact proxied; /** * Default constructor. */ public ProxyArtifact() { } /** * Constructor to create a new proxy artifact around a given artifact. * @param proxied The artifact to be proxied. */ public ProxyArtifact(Artifact proxied) { this.proxied = proxied; } /** * The currently proxied artifact. * @return The proxied artifact. */ public Artifact getProxied() { return proxied; } /** * Explicitly set the proxied artifacts. * @param proxied */ public void setProxied(Artifact proxied) { this.proxied = proxied; } @Override public void setIdentifier(String identifier) { this.identifier = identifier; if (proxied != null) proxied.setIdentifier(identifier); } /** * Method to check if the current proxied artifact should be replaced * by a new one coming from the call context. * @param callContext */ protected void checkReplacement(CallContext callContext) { Object replacement = callContext.getContextValue(REPLACE_PROXY); if (replacement instanceof Artifact) { setProxied((Artifact)replacement); } } @Override public String hash() { return proxied != null ? proxied.hash() : super.hash(); } @Override public Document describe(Document data, CallContext context) { try { return proxied != null ? proxied.describe(data, context) : super.describe(data, context); } finally { checkReplacement(context); } } @Override public Document advance(Document target, CallContext context) { try { return proxied != null ? proxied.advance(target, context) : super.advance(target, context); } finally { checkReplacement(context); } } @Override public Document feed(Document target, CallContext context) { try { return proxied != null ? proxied.feed(target, context) : super.feed(target, context); } finally { checkReplacement(context); } } @Override public void out( Document format, OutputStream out, CallContext context ) throws IOException { try { if (proxied != null) { proxied.out(format, out, context); } else { super.out(format, out, context); } } finally { checkReplacement(context); } } @Override public void endOfLife(Object context) { if (proxied != null) { proxied.endOfLife(context); } else { super.endOfLife(context); } } @Override public void cleanup(Object context) { if (proxied != null) proxied.cleanup(context); else super.cleanup(context); } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :