Java tutorial
/* * 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.vfs2.provider.sftp; import java.io.IOException; import java.io.InputStreamReader; import java.util.Collection; import org.apache.commons.vfs2.Capability; import org.apache.commons.vfs2.FileObject; import org.apache.commons.vfs2.FileSystemException; import org.apache.commons.vfs2.FileSystemOptions; import org.apache.commons.vfs2.UserAuthenticationData; import org.apache.commons.vfs2.provider.AbstractFileName; import org.apache.commons.vfs2.provider.AbstractFileSystem; import org.apache.commons.vfs2.provider.GenericFileName; import org.apache.commons.vfs2.util.UserAuthenticatorUtils; import com.jcraft.jsch.ChannelExec; import com.jcraft.jsch.ChannelSftp; import com.jcraft.jsch.JSchException; import com.jcraft.jsch.Session; import com.jcraft.jsch.SftpException; /** * Represents the files on an SFTP server. */ public class SftpFileSystem extends AbstractFileSystem { private static final int SLEEP_MILLIS = 100; private static final int EXEC_BUFFER_SIZE = 128; private static final long LAST_MOD_TIME_ACCURACY = 1000L; private Session session; // private final JSch jSch; private ChannelSftp idleChannel; /** * Cache for the user ID (-1 when not set) */ private int uid = -1; /** * Cache for the user groups ids (null when not set) */ private int[] groupsIds; protected SftpFileSystem(final GenericFileName rootName, final Session session, final FileSystemOptions fileSystemOptions) { super(rootName, null, fileSystemOptions); this.session = session; } @Override protected void doCloseCommunicationLink() { if (idleChannel != null) { idleChannel.disconnect(); idleChannel = null; } if (session != null) { session.disconnect(); session = null; } } /** * Returns an SFTP channel to the server. * * @return new or reused channel, never null. * @throws FileSystemException if a session cannot be created. * @throws IOException if an I/O error is detected. */ protected ChannelSftp getChannel() throws IOException { ensureSession(); try { // Use the pooled channel, or create a new one final ChannelSftp channel; if (idleChannel != null) { channel = idleChannel; idleChannel = null; } else { channel = (ChannelSftp) session.openChannel("sftp"); channel.connect(); final Boolean userDirIsRoot = SftpFileSystemConfigBuilder.getInstance() .getUserDirIsRoot(getFileSystemOptions()); final String workingDirectory = getRootName().getPath(); if (workingDirectory != null && (userDirIsRoot == null || !userDirIsRoot.booleanValue())) { try { channel.cd(workingDirectory); } catch (final SftpException e) { throw new FileSystemException("vfs.provider.sftp/change-work-directory.error", workingDirectory, e); } } } final String fileNameEncoding = SftpFileSystemConfigBuilder.getInstance() .getFileNameEncoding(getFileSystemOptions()); if (fileNameEncoding != null) { try { channel.setFilenameEncoding(fileNameEncoding); } catch (final SftpException e) { throw new FileSystemException("vfs.provider.sftp/filename-encoding.error", fileNameEncoding); } } return channel; } catch (final JSchException e) { throw new FileSystemException("vfs.provider.sftp/connect.error", getRootName(), e); } } /** * Ensures that the session link is established. * * @throws FileSystemException if a session cannot be created. */ private void ensureSession() throws FileSystemException { if (this.session == null || !this.session.isConnected()) { doCloseCommunicationLink(); // channel closed. e.g. by freeUnusedResources, but now we need it again Session session; UserAuthenticationData authData = null; try { final GenericFileName rootName = (GenericFileName) getRootName(); authData = UserAuthenticatorUtils.authenticate(getFileSystemOptions(), SftpFileProvider.AUTHENTICATOR_TYPES); session = SftpClientFactory.createConnection(rootName.getHostName(), rootName.getPort(), UserAuthenticatorUtils.getData(authData, UserAuthenticationData.USERNAME, UserAuthenticatorUtils.toChar(rootName.getUserName())), UserAuthenticatorUtils.getData(authData, UserAuthenticationData.PASSWORD, UserAuthenticatorUtils.toChar(rootName.getPassword())), getFileSystemOptions()); } catch (final Exception e) { throw new FileSystemException("vfs.provider.sftp/connect.error", getRootName(), e); } finally { UserAuthenticatorUtils.cleanup(authData); } this.session = session; } } /** * Returns a channel to the pool. * * @param channel the used channel. */ protected void putChannel(final ChannelSftp channel) { if (idleChannel == null) { // put back the channel only if it is still connected if (channel.isConnected() && !channel.isClosed()) { idleChannel = channel; } } else { channel.disconnect(); } } /** * Adds the capabilities of this file system. */ @Override protected void addCapabilities(final Collection<Capability> caps) { caps.addAll(SftpFileProvider.capabilities); } /** * Creates a file object. This method is called only if the requested * file is not cached. */ @Override protected FileObject createFile(final AbstractFileName name) throws FileSystemException { return new SftpFileObject(name, this); } /** * Last modification time is only an int and in seconds, thus can be off by 999. * * @return 1000 */ @Override public double getLastModTimeAccuracy() { return LAST_MOD_TIME_ACCURACY; } /** * Gets the (numeric) group IDs. * * @return the (numeric) group IDs. * @throws JSchException If a problem occurs while retrieving the group IDs. * @throws IOException if an I/O error is detected. * @since 2.1 */ public int[] getGroupsIds() throws JSchException, IOException { if (groupsIds == null) { final StringBuilder output = new StringBuilder(); final int code = executeCommand("id -G", output); if (code != 0) { throw new JSchException( "Could not get the groups id of the current user (error code: " + code + ")"); } // Retrieve the different groups final String[] groups = output.toString().trim().split("\\s+"); final int[] groupsIds = new int[groups.length]; for (int i = 0; i < groups.length; i++) { groupsIds[i] = Integer.parseInt(groups[i]); } this.groupsIds = groupsIds; } return groupsIds; } /** * Get the (numeric) group IDs. * * @return The numeric user ID * @throws JSchException If a problem occurs while retrieving the group ID. * @throws IOException if an I/O error is detected. * @since 2.1 */ public int getUId() throws JSchException, IOException { if (uid < 0) { final StringBuilder output = new StringBuilder(); final int code = executeCommand("id -u", output); if (code != 0) { throw new FileSystemException( "Could not get the user id of the current user (error code: " + code + ")"); } uid = Integer.parseInt(output.toString().trim()); } return uid; } /** * Execute a command and returns the (standard) output through a StringBuilder. * * @param command The command * @param output The output * @return The exit code of the command * @throws JSchException if a JSch error is detected. * @throws FileSystemException if a session cannot be created. * @throws IOException if an I/O error is detected. */ private int executeCommand(final String command, final StringBuilder output) throws JSchException, IOException { ensureSession(); final ChannelExec channel = (ChannelExec) session.openChannel("exec"); channel.setCommand(command); channel.setInputStream(null); final InputStreamReader stream = new InputStreamReader(channel.getInputStream()); channel.setErrStream(System.err, true); channel.connect(); // Read the stream final char[] buffer = new char[EXEC_BUFFER_SIZE]; int read; while ((read = stream.read(buffer, 0, buffer.length)) >= 0) { output.append(buffer, 0, read); } stream.close(); // Wait until the command finishes (should not be long since we read the output stream) while (!channel.isClosed()) { try { Thread.sleep(SLEEP_MILLIS); } catch (final Exception ee) { // TODO: swallow exception, really? } } channel.disconnect(); return channel.getExitStatus(); } }