Added getInstance Method to DbXRefService

src/main/java/de/cebitec/common/dbxref/DbXRefService.java

@@ -18,18 +18,36 @@ package de.cebitec.common.dbxref;
 
 import de.cebitec.common.dbxref.api.DbXRef;
 import de.cebitec.common.dbxref.api.Resource;
+import de.cebitec.common.dbxref.api.Resource.Type;
 import java.util.Collection;
+import java.util.Iterator;
+import java.util.ServiceLoader;
 
 /**
  * A DbXRefService resolves dbxrefs to resources. In order to obtain a dbxref use the factory methods.
- * 
- * @see #create(CharSequence) 
- * @see #create(CharSequence, CharSequence)  
+ *
+ * @see #create(CharSequence)
+ * @see #create(CharSequence, CharSequence)
  *
  * @author Lukas Jelonek {@literal <Lukas.Jelonek at computational.bio.uni-giessen.de>}
  */
 public interface DbXRefService {
 
+    /**
+     * Retrieves an instance of DbXRefService via the serviceloader.
+     *
+     * @return
+     */
+    static DbXRefService getInstance() {
+        ServiceLoader<DbXRefService> loader = ServiceLoader.load(DbXRefService.class);
+        final Iterator<DbXRefService> it = loader.iterator();
+        if (it.hasNext()) {
+            return it.next();
+        } else {
+            return DbXRefResourceRegistry.getDefault();
+        }
+    }
+
     /**
      * Factory method for database cross references. Can instantiate any database cross reference, regardless of a valid
      * database or valid identifier.