How to read file from ZIP using InputStream?

Question

I must get file content from ZIP archive (only one file, I know its name) using SFTP. The only thing I'm having is ZIP's InputStream. Most examples show how get content using this statement:

ZipFile zipFile = new ZipFile("location");

But as I said, I don't have ZIP file on my local machine and I don't want to download it. Is an InputStream enough to read?

UPD: This is how I do:

import java.util.zip.ZipInputStream;

import com.jcraft.jsch.Channel;
import com.jcraft.jsch.ChannelSftp;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;

public class SFTP {


    public static void main(String[] args) {

        String SFTPHOST = "host";
        int SFTPPORT = 3232;
        String SFTPUSER = "user";
        String SFTPPASS = "mypass";
        String SFTPWORKINGDIR = "/dir/work";
        Session session = null;
        Channel channel = null;
        ChannelSftp channelSftp = null;
        try {
            JSch jsch = new JSch();
            session = jsch.getSession(SFTPUSER, SFTPHOST, SFTPPORT);
            session.setPassword(SFTPPASS);
            java.util.Properties config = new java.util.Properties();
            config.put("StrictHostKeyChecking", "no");
            session.setConfig(config);
            session.connect();
            channel = session.openChannel("sftp");
            channel.connect();
            channelSftp = (ChannelSftp) channel;
            channelSftp.cd(SFTPWORKINGDIR);
            ZipInputStream stream = new ZipInputStream(channelSftp.get("file.zip"));
            ZipEntry entry = zipStream.getNextEntry();
            System.out.println(entry.getName); //Yes, I got its name, now I need to get content
        } catch (Exception ex) {
            ex.printStackTrace();
        } finally {
            session.disconnect();
            channelSftp.disconnect();
            channel.disconnect();
        }


    }
}

Answer 1

Below is a simple example on how to extract a ZIP File, you will need to check if the file is a directory. But this is the simplest.

The step you are missing is reading the input stream and writing the contents to a buffer which is written to an output stream.

// Expands the zip file passed as argument 1, into the
// directory provided in argument 2
public static void main(String args[]) throws Exception
{
    if(args.length != 2)
    {
        System.err.println("zipreader zipfile outputdir");
        return;
    }

    // create a buffer to improve copy performance later.
    byte[] buffer = new byte[2048];

    // open the zip file stream
    InputStream theFile = new FileInputStream(args[0]);
    ZipInputStream stream = new ZipInputStream(theFile);
    String outdir = args[1];

    try
    {

        // now iterate through each item in the stream. The get next
        // entry call will return a ZipEntry for each file in the
        // stream
        ZipEntry entry;
        while((entry = stream.getNextEntry())!=null)
        {
            String s = String.format("Entry: %s len %d added %TD",
                            entry.getName(), entry.getSize(),
                            new Date(entry.getTime()));
            System.out.println(s);

            // Once we get the entry from the stream, the stream is
            // positioned read to read the raw data, and we keep
            // reading until read returns 0 or less.
            String outpath = outdir + "/" + entry.getName();
            FileOutputStream output = null;
            try
            {
                output = new FileOutputStream(outpath);
                int len = 0;
                while ((len = stream.read(buffer)) > 0)
                {
                    output.write(buffer, 0, len);
                }
            }
            finally
            {
                // we must always close the output file
                if(output!=null) output.close();
            }
        }
    }
    finally
    {
        // we must always close the zip file.
        stream.close();
    }
}

Code excerpt came from the following site:

http://www.thecoderscorner.com/team-blog/java-and-jvm/12-reading-a-zip-file-from-java-using-zipinputstream#.U4RAxYamixR