Kiview ftpclient (#4456)

* Add example for FTP client

Using Apache Commons Net

* Add missing resource

* Fix wrong file download in integration test

* Add example for using FTP support in JDK

* Close input stream after copy

* Fix test name

libraries/src/test/java/com/baeldung/ftp/FtpClientIntegrationTest.java

@@ -0,0 +1,73 @@
+package com.baeldung.ftp;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockftpserver.fake.FakeFtpServer;
+import org.mockftpserver.fake.UserAccount;
+import org.mockftpserver.fake.filesystem.DirectoryEntry;
+import org.mockftpserver.fake.filesystem.FileEntry;
+import org.mockftpserver.fake.filesystem.FileSystem;
+import org.mockftpserver.fake.filesystem.UnixFakeFileSystem;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.util.Collection;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class FtpClientIntegrationTest {
+
+    private FakeFtpServer fakeFtpServer;
+
+    private FtpClient ftpClient;
+
+    @Before
+    public void setup() throws IOException {
+        fakeFtpServer = new FakeFtpServer();
+        fakeFtpServer.addUserAccount(new UserAccount("user", "password", "/data"));
+
+        FileSystem fileSystem = new UnixFakeFileSystem();
+        fileSystem.add(new DirectoryEntry("/data"));
+        fileSystem.add(new FileEntry("/data/foobar.txt", "abcdef 1234567890"));
+        fakeFtpServer.setFileSystem(fileSystem);
+        fakeFtpServer.setServerControlPort(0);
+
+        fakeFtpServer.start();
+
+        ftpClient = new FtpClient("localhost", fakeFtpServer.getServerControlPort(), "user", "password");
+        ftpClient.open();
+    }
+
+    @After
+    public void teardown() throws IOException {
+        ftpClient.close();
+        fakeFtpServer.stop();
+    }
+
+    @Test
+    public void givenRemoteFile_whenListingRemoteFiles_thenItIsContainedInList() throws IOException {
+        Collection<String> files = ftpClient.listFiles("");
+
+        assertThat(files).contains("foobar.txt");
+    }
+
+    @Test
+    public void givenRemoteFile_whenDownloading_thenItIsOnTheLocalFilesystem() throws IOException {
+        ftpClient.downloadFile("/foobar.txt", "downloaded_buz.txt");
+
+        assertThat(new File("downloaded_buz.txt")).exists();
+        new File("downloaded_buz.txt").delete(); // cleanup
+    }
+
+    @Test
+    public void givenLocalFile_whenUploadingIt_thenItExistsOnRemoteLocation() throws URISyntaxException, IOException {
+        File file = new File(getClass().getClassLoader().getResource("ftp/baz.txt").toURI());
+
+        ftpClient.putFileToPath(file, "/buz.txt");
+
+        assertThat(fakeFtpServer.getFileSystem().exists("/buz.txt")).isTrue();
+    }
+
+}