1 files changed, 107 insertions, 0 deletions
diff --git a/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/lib/impl/backend/BackendLoader.java b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/lib/impl/backend/BackendLoader.java
new file mode 100644
index 00000000..4e00209a
--- /dev/null
+++ b/pdf-as-lib/src/main/java/at/gv/egiz/pdfas/lib/impl/backend/BackendLoader.java
@@ -0,0 +1,107 @@
+package at.gv.egiz.pdfas.lib.impl.backend;
+
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.ServiceLoader;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import at.gv.egiz.pdfas.common.exceptions.ErrorConstants;
+import at.gv.egiz.pdfas.common.exceptions.PDFASError;
+import at.gv.egiz.pdfas.lib.api.Configuration;
+import at.gv.egiz.pdfas.lib.backend.PDFASBackend;
+
+/**
+ * The Class BackendLoader.
+ */
+public class BackendLoader implements ErrorConstants {
+	
+	/** The Constant logger. */
+	private static final Logger logger = LoggerFactory
+			.getLogger(BackendLoader.class);
+	
+	/** The pdf as backend loader. */
+	private static ServiceLoader<PDFASBackend> pdfAsBackendLoader = ServiceLoader.load(PDFASBackend.class);
+	
+	/** The available backends. */
+	private static Map<String, PDFASBackend> availableBackends = new HashMap<String, PDFASBackend>();
+	
+	/** The Constant BACKEND_CONFIG. */
+	public static final String BACKEND_CONFIG = "runtime.backend";
+	
+	/** The default backend. */
+	private static PDFASBackend defaultBackend = null; 
+	
+	static {
+		logger.debug("building PDF-AS Backends");
+		
+		Iterator<PDFASBackend> backendIterator = pdfAsBackendLoader.iterator();
+		
+		while(backendIterator.hasNext()) {
+			PDFASBackend backend = backendIterator.next();
+			logger.debug("Loading " + backend.getName() + " [" + backend.getClass().getName() + "]");
+			availableBackends.put(backend.getName(), backend);
+			logger.debug("PDF-Backend added " + backend.getName());
+			if(backend.usedAsDefault()) {
+				defaultBackend = backend;
+				logger.debug("PDF-Backend added as default " + backend.getName());
+			}
+		}
+		
+		logger.debug("PDF-AS Backends constructed");
+		
+		if(defaultBackend != null) {
+			logger.debug("Default backend is " + defaultBackend.getName());
+		}
+	}
+	
+	/**
+	 * Gets the PDFAS backend.
+	 *
+	 * @param configuration the configuration
+	 * @return the PDFAS backend
+	 * @throws PDFASError the PDFAS error
+	 */
+	public static PDFASBackend getPDFASBackend(Configuration configuration) throws PDFASError {
+		String backendName = configuration.getValue(BACKEND_CONFIG);
+		return getPDFASBackend(backendName);
+	}
+	
+	/**
+	 * Gets the PDFAS backend.
+	 *
+	 * @param name the name
+	 * @return the PDFAS backend
+	 * @throws PDFASError the PDFAS error
+	 */
+	public static PDFASBackend getPDFASBackend(String name) throws PDFASError {
+		if(name != null) {
+			if(availableBackends.containsKey(name)) {
+				return availableBackends.get(name);
+			}
+			throw new PDFASError(ERROR_NO_BACKEND);
+		}
+		
+		if(defaultBackend != null) {
+			return defaultBackend;
+		}
+		
+		throw new PDFASError(ERROR_NO_BACKEND);
+	}
+	
+	/**
+	 * Gets the PDFAS backend.
+	 *
+	 * @return the PDFAS backend
+	 * @throws PDFASError the PDFAS error
+	 */
+	public static PDFASBackend getPDFASBackend() throws PDFASError {
+		if(defaultBackend != null) {
+			return defaultBackend;
+		}
+		
+		throw new PDFASError(ERROR_NO_BACKEND);
+	}
+}