Ant example source code file (ScpFromMessage.java)

This example Ant source code file (ScpFromMessage.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

buffer_size, bytearrayoutputstream, file, file, fileoutputstream, inputstream, io, ioexception, ioexception, outputstream, scpfrommessage, scpfrommessage, session, string, string

The ScpFromMessage.java source code

/*
 *  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.tools.ant.taskdefs.optional.ssh;

import java.io.File;
import java.io.IOException;
import java.io.EOFException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.FileOutputStream;
import java.io.ByteArrayOutputStream;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;
import com.jcraft.jsch.Channel;

/**
 * A helper object representing an scp download.
 */
public class ScpFromMessage extends AbstractSshMessage {

    private static final byte LINE_FEED = 0x0a;
    private static final int BUFFER_SIZE = 1024;

    private String remoteFile;
    private File localFile;
    private boolean isRecursive = false;

    /**
     * Constructor for ScpFromMessage
     * @param session the ssh session to use
     */
    public ScpFromMessage(Session session) {
        super(session);
    }

    /**
     * Constructor for ScpFromMessage
     * @param verbose if true do verbose logging
     * @param session the ssh session to use
     * @since Ant 1.7
     */
    public ScpFromMessage(boolean verbose, Session session) {
        super(verbose, session);
    }

    /**
     * Constructor for ScpFromMessage.
     * @param verbose if true log extra information
     * @param session the Scp session to use
     * @param aRemoteFile the remote file name
     * @param aLocalFile  the local file
     * @param recursive   if true use recursion (-r option to scp)
     * @since Ant 1.6.2
     */
    public ScpFromMessage(boolean verbose,
                          Session session,
                          String aRemoteFile,
                          File aLocalFile,
                          boolean recursive) {
        super(verbose, session);
        this.remoteFile = aRemoteFile;
        this.localFile = aLocalFile;
        this.isRecursive = recursive;
    }

    /**
     * Constructor for ScpFromMessage.
     * @param session the Scp session to use
     * @param aRemoteFile the remote file name
     * @param aLocalFile  the local file
     * @param recursive   if true use recursion (-r option to scp)
     */
    public ScpFromMessage(Session session,
                           String aRemoteFile,
                           File aLocalFile,
                           boolean recursive) {
        this(false, session, aRemoteFile, aLocalFile, recursive);
    }

    /**
     * Carry out the transfer.
     * @throws IOException on i/o errors
     * @throws JSchException on errors detected by scp
     */
    public void execute() throws IOException, JSchException {
        String command = "scp -f ";
        if (isRecursive) {
            command += "-r ";
        }
        command += remoteFile;
        Channel channel = openExecChannel(command);
        try {
            // get I/O streams for remote scp
            OutputStream out = channel.getOutputStream();
            InputStream in = channel.getInputStream();

            channel.connect();

            sendAck(out);
            startRemoteCpProtocol(in, out, localFile);
        } finally {
            if (channel != null) {
                channel.disconnect();
            }
        }
        log("done\n");
    }

    private void startRemoteCpProtocol(InputStream in,
                                       OutputStream out,
                                       File localFile) throws IOException {
        File startFile = localFile;
        while (true) {
            // C0644 filesize filename - header for a regular file
            // T time 0 time 0\n - present if perserve time.
            // D directory - this is the header for a directory.
            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            while (true) {
                int read = in.read();
                if (read < 0) {
                    return;
                }
                if ((byte) read == LINE_FEED) {
                    break;
                }
                stream.write(read);
            }
            String serverResponse = stream.toString("UTF-8");
            if (serverResponse.charAt(0) == 'C') {
                parseAndFetchFile(serverResponse, startFile, out, in);
            } else if (serverResponse.charAt(0) == 'D') {
                startFile = parseAndCreateDirectory(serverResponse,
                        startFile);
                sendAck(out);
            } else if (serverResponse.charAt(0) == 'E') {
                startFile = startFile.getParentFile();
                sendAck(out);
            } else if (serverResponse.charAt(0) == '\01'
                    || serverResponse.charAt(0) == '\02') {
                // this indicates an error.
                throw new IOException(serverResponse.substring(1));
            }
        }
    }

    private File parseAndCreateDirectory(String serverResponse,
                                         File localFile) {
        int start = serverResponse.indexOf(" ");
        // appears that the next token is not used and it's zero.
        start = serverResponse.indexOf(" ", start + 1);
        String directoryName = serverResponse.substring(start + 1);
        if (localFile.isDirectory()) {
            File dir = new File(localFile, directoryName);
            dir.mkdir();
            log("Creating: " + dir);
            return dir;
        }
        return null;
    }

    private void parseAndFetchFile(String serverResponse,
                                   File localFile,
                                   OutputStream out,
                                   InputStream in) throws IOException {
        int start = 0;
        int end = serverResponse.indexOf(" ", start + 1);
        start = end + 1;
        end = serverResponse.indexOf(" ", start + 1);
        long filesize = Long.parseLong(serverResponse.substring(start, end));
        String filename = serverResponse.substring(end + 1);
        log("Receiving: " + filename + " : " + filesize);
        File transferFile = (localFile.isDirectory())
                ? new File(localFile, filename)
                : localFile;
        fetchFile(transferFile, filesize, out, in);
        waitForAck(in);
        sendAck(out);
    }

    private void fetchFile(File localFile,
                            long filesize,
                            OutputStream out,
                            InputStream in) throws IOException {
        byte[] buf = new byte[BUFFER_SIZE];
        sendAck(out);

        // read a content of lfile
        FileOutputStream fos = new FileOutputStream(localFile);
        int length;
        long totalLength = 0;
        long startTime = System.currentTimeMillis();

        // only track progress for files larger than 100kb in verbose mode
        boolean trackProgress = getVerbose() && filesize > 102400;
        // since filesize keeps on decreasing we have to store the
        // initial filesize
        long initFilesize = filesize;
        int percentTransmitted = 0;

        try {
            while (true) {
                length = in.read(buf, 0,
                                 (BUFFER_SIZE < filesize) ? BUFFER_SIZE
                                                          : (int) filesize);
                if (length < 0) {
                    throw new EOFException("Unexpected end of stream.");
                }
                fos.write(buf, 0, length);
                filesize -= length;
                totalLength += length;
                if (filesize == 0) {
                    break;
                }

                if (trackProgress) {
                    percentTransmitted = trackProgress(initFilesize,
                                                       totalLength,
                                                       percentTransmitted);
                }
            }
        } finally {
            long endTime = System.currentTimeMillis();
            logStats(startTime, endTime, totalLength);
            fos.flush();
            fos.close();
        }
    }

}