Java

SFTP Upload Large File in Parts

See more SFTP Examples

Demonstrates how to split a large file into N parts and then upload each part separately. This technique can be used to potentially avoid limits a SFTP server might impose on upload file size. Chilkat2 Java

import com.chilkatsoft.chilkat2.BinData;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.FileAccess;
import com.chilkatsoft.chilkat2.SFtp;

public class ChilkatExample {

    public static void main(String[] args) {
        // This example assumes the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        SFtp sftp = new SFtp();

        // Set some timeouts, in milliseconds:
        sftp.setConnectTimeoutMs(5000);
        sftp.setIdleTimeoutMs(10000);

        // Connect to the SSH server.
        // The standard SSH port = 22
        // The hostname may be a hostname or IP address.
        String hostname = "sftp.example.com";
        int port = 22;
        String handle;
        try {
            sftp.connect(hostname, port);

            // Authenticate with the SSH server.  Chilkat SFTP supports
            // both password-based authenication as well as public-key
            // authentication.  This example uses password authenication.
            sftp.authenticatePw("myLogin", "myPassword");

            // After authenticating, the SFTP subsystem must be initialized:
            sftp.initializeSftp();

            // Open a remote file for writing on the SSH server.
            // If the file already exists, it is overwritten.
            // (Specify "createNew" instead of "createTruncate" to
            // prevent overwriting existing files.)
            handle = sftp.openFile("big.zip", "writeOnly", "createTruncate");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // We're going to upload the local file "qa_data/zips/big.zip" (a relative local path from our current working directory)
        // to the SFTP server.
        String localFilePath = "qa_data/zips/big.zip";

        // Rather than uploading in one shot, we'll read the local file in chunks
        // and upload a chunk at a time.
        FileAccess fac = new FileAccess();

        try {
            fac.openForRead(localFilePath);
        } catch (ChilkatException e) {
            sftp.closeHandle(handle);
            System.out.println(e.getLastErrorText());
            return;
        }

        // If we were to split the local file into 128K chunks, how many chunks (blocks) would
        // we have, including the last partial block?
        int blockSize = 131072;
        int numBlocks = fac.getNumBlocks(blockSize);
        System.out.println("Number of blocks = " + numBlocks);

        BinData bd = new BinData();
        int i = 0;
        while (i < numBlocks) {
            // Read the Nth block, which gets appended to the bd.  (which means
            // we must clear the contents of bd before the next iteration)
            try {
                fac.readBlockBd(i, blockSize, bd);
            } catch (ChilkatException e) {
                sftp.closeHandle(handle);
                System.out.println(e.getLastErrorText());
                return;
            }

            // Upload this block to the open remote file.
            try {
                sftp.writeFileBd(handle, bd);
            } catch (ChilkatException e) {
                System.out.println(e.getLastErrorText());
                return;
            }

            // Clear the contents for the next iteration.
            bd.clear();

            i = i + 1;
        }

        // Close the local file.
        fac.fileClose();

        // -----------------------------------------------------------------------------
        // This is important.  You must close the handle on the server.
        // Otherwise open handles will accumulate on the server until eventually a limit
        // is reached and the server will fail on a call to OpenFile.
        // -----------------------------------------------------------------------------

        // Close the remote file handle on the server.
        try {
            sftp.closeHandle(handle);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("Success.");
    }
}