Add Duration APIs to specify timeouts.

- FTP] Add FTPClient.getControlKeepAliveReplyTimeoutDuration().
- FTP] Add FTPClient.setControlKeepAliveReplyTimeout(Duration).
- FTP] Add FTPClient.getControlKeepAliveTimeoutDuration().
- FTP] Add FTPClient.setControlKeepAliveTimeout(Duration).

src/changes/changes.xml

@@ -66,10 +66,22 @@ The <action> type attribute can be add,update,fix,remove.
         <release version="3.9.0" date="2021-MM-DD" description="Maintenance and bug fix release (Java 8).">
             <!-- ADD -->
            <action type="add" dev="ggregory" due-to="Gary Gregory">
-            Add FTPClient.mdtmInstant(String).
+            [FTP] Add FTPClient.mdtmInstant(String).
             </action>
            <action type="add" dev="ggregory" due-to="Gary Gregory">
-            Add MLSxEntryParser.parseGmtInstant(String).
+            [FTP] Add MLSxEntryParser.parseGmtInstant(String).
+            </action>
+           <action type="add" dev="ggregory" due-to="Gary Gregory">
+            [FTP] Add FTPClient.getControlKeepAliveReplyTimeoutDuration().
+            </action>
+           <action type="add" dev="ggregory" due-to="Gary Gregory">
+            [FTP] Add FTPClient.setControlKeepAliveReplyTimeout(Duration).
+            </action>
+           <action type="add" dev="ggregory" due-to="Gary Gregory">
+            [FTP] Add FTPClient.getControlKeepAliveTimeoutDuration().
+            </action>
+           <action type="add" dev="ggregory" due-to="Gary Gregory">
+            [FTP] Add FTPClient.setControlKeepAliveTimeout(Duration).
             </action>
         </release>
         <release version="3.8.0" date="2021-02-13" description="Maintenance and bug fix release (Java 7).">
@@ -81,14 +93,14 @@ The <action> type attribute can be add,update,fix,remove.
             Add and use SocketClient.applySocketAttributes().
             </action>
             <action type="add" dev="ggregory" due-to="Gary Gregory">
-            Add FTPClient.hasFeature(FTPCmd).
+            [FTP] Add FTPClient.hasFeature(FTPCmd).
             </action>
             <action type="add" dev="ggregory" due-to="Gary Gregory">
-            Add FTPClient.mdtmCalendar(String).
+            [FTP] Add FTPClient.mdtmCalendar(String).
             </action>
             <!--  FIX -->
             <action type="fix" dev="ggregory" due-to="Gary Gregory">
-            Fix concurrent counting of chunks in IMAPExportMbox.
+            [IMAP] Fix concurrent counting of chunks in IMAPExportMbox.
             </action>
             <action type="fix" dev="ggregory" due-to="Gary Gregory">
             Fix possible if rare NPEs in tests.

src/main/java/org/apache/commons/net/examples/ftp/FTPClientExample.java

@@ -25,6 +25,7 @@
 import java.io.PrintWriter;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
+import java.time.Duration;
 import java.util.Arrays;
 
 import org.apache.commons.net.PrintCommandListener;
@@ -298,10 +299,10 @@ else if (args[base].equals("-#")) {
             ftp.setCopyStreamListener(createListener());
         }
         if (keepAliveTimeoutSeconds >= 0) {
-            ftp.setControlKeepAliveTimeout(keepAliveTimeoutSeconds);
+            ftp.setControlKeepAliveTimeout(Duration.ofSeconds(keepAliveTimeoutSeconds));
         }
         if (controlKeepAliveReplyTimeoutMillis >= 0) {
-            ftp.setControlKeepAliveReplyTimeout(controlKeepAliveReplyTimeoutMillis);
+            ftp.setControlKeepAliveReplyTimeout(Duration.ofMillis(controlKeepAliveReplyTimeoutMillis));
         }
         if (encoding != null) {
             ftp.setControlEncoding(encoding);

src/main/java/org/apache/commons/net/ftp/DurationUtils.java

@@ -0,0 +1,43 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.net.ftp;
+
+import java.time.Duration;
+
+/** Temporary until Commons Lang 3.12.0. */
+class DurationUtils {
+
+    /**
+     * Tests whether the given Duration is positive (>0).
+     *
+     * @param duration the value to test
+     * @return whether the given Duration is positive (>0).
+     */
+    static boolean isPositive(final Duration duration) {
+        return duration != null && !duration.isNegative() && !duration.isZero();
+    }
+
+    static int toMillisInt(final Duration duration) {
+        final long millis = duration.toMillis();
+        return millis > 0 ? (int) Math.min(millis, Integer.MAX_VALUE) : (int) Math.max(millis, Integer.MIN_VALUE);
+    }
+
+    static Duration zeroIfNull(final Duration controlIdle) {
+        return controlIdle == null ? Duration.ZERO : controlIdle;
+    }
+}