added static utility method for closing a socket quietly

Dealing with IOException on Socket.close in each finally where it
appears is a pain...

logback-core/src/main/java/ch/qos/logback/core/util/SocketUtil.java

@@ -0,0 +1,40 @@
+/**
+ * Logback: the reliable, generic, fast and flexible logging framework.
+ * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
+ *
+ * This program and the accompanying materials are dual-licensed under
+ * either the terms of the Eclipse Public License v1.0 as published by
+ * the Eclipse Foundation
+ *
+ *   or (per the licensee's choosing)
+ *
+ * under the terms of the GNU Lesser General Public License version 2.1
+ * as published by the Free Software Foundation.
+ */
+package ch.qos.logback.core.util;
+
+import java.io.IOException;
+import java.net.Socket;
+
+/**
+ * Static utility methods for {@link Socket} objects.
+ *
+ * @author Carl Harris
+ */
+public class SocketUtil {
+
+  /**
+   * Closes a socket while suppressing any {@code IOException} that occurs.
+   * @param socket the socket to close
+   */
+  public static void closeQuietly(Socket socket) {
+    if (socket == null) return;
+    try {
+      socket.close();
+    }
+    catch (IOException ex) {
+      assert true;  // avoid an empty catch
+    }
+  }
+
+}