Add a file query.

diff --git a/src/main/java/net/pterodactylus/reactor/queries/FileQuery.java b/src/main/java/net/pterodactylus/reactor/queries/FileQuery.java
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index 0000000..64a72f4
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+++ b/src/main/java/net/pterodactylus/reactor/queries/FileQuery.java
@@ -0,0 +1,66 @@
+/*
+ * Reactor - FileQuery.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.reactor.queries;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.io.File;
+
+import net.pterodactylus.reactor.Query;
+import net.pterodactylus.reactor.states.FileState;
+
+/**
+ * Queries the filesystem about a file.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class FileQuery implements Query<FileState> {
+
+       /** The name of the file to query. */
+       private final String filename;
+
+       /**
+        * Creates a new file query.
+        *
+        * @param filename
+        *            The name of the file to query
+        */
+       public FileQuery(String filename) {
+               this.filename = checkNotNull(filename, "filename must not be null");
+       }
+
+       //
+       // QUERY METHODS
+       //
+
+       /**
+        * {@inheritDoc}
+        */
+       @Override
+       public FileState state() {
+               File file = new File(filename);
+               if (!file.exists()) {
+                       return new FileState(false, false, -1, -1);
+               }
+               if (!file.canRead()) {
+                       return new FileState(true, false, -1, -1);
+               }
+               return new FileState(true, true, file.length(), file.lastModified());
+       }
+
+}