Java URL Download downloadFileIfAvailable(URL url, File destination)

Description

download File If Available

License

GNU General Public License

Declaration

public static File downloadFileIfAvailable(URL url, File destination)
            throws IOException 

Method Source Code

//package com.java2s;
/**//  www. j  av  a2s  .  c  o m
 *                    BioJava development code
 *
 * This code may be freely distributed and modified under the
 * terms of the GNU Lesser General Public Licence.  This should
 * be distributed with the code.  If you do not have a copy,
 * see:
 *
 *      http://www.gnu.org/copyleft/lesser.html
 *
 * Copyright for this code is held jointly by the individual
 * authors.  These should be listed in @author doc comments.
 *
 * For more information on the BioJava project and its aims,
 * or to join the biojava-l mailing list, visit the home page
 * at:
 *
 *      http://www.biojava.org/
 *
 * Created on Feb 23, 2012
 * Created by Andreas Prlic
 *
 * @since 3.0.2
 */

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URL;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

public class Main {
    public static File downloadFileIfAvailable(URL url, File destination)
            throws IOException {

        InputStream uStream = null;
        InputStream conn = null;
        try {
            uStream = url.openStream();
            conn = new GZIPInputStream(uStream);
        } catch (IOException e1) {
            System.err.println("Problem while downloading file " + url);
            //e1.printStackTrace();
            try {
                if (uStream != null) {
                    uStream.close();
                }

                if (conn != null) {
                    conn.close();
                }

            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

        FileOutputStream outPut = null;
        GZIPOutputStream gzOutPut = null;
        File tempFile = File.createTempFile(getFilePrefix(destination), "."
                + getFileExtension(destination));
        try {

            outPut = new FileOutputStream(tempFile);
            gzOutPut = new GZIPOutputStream(outPut);
            PrintWriter pw = new PrintWriter(gzOutPut);

            BufferedReader fileBuffer = new BufferedReader(
                    new InputStreamReader(conn));
            String line;
            while ((line = fileBuffer.readLine()) != null) {
                pw.println(line);
            }
            pw.flush();
            pw.close();

            outPut.flush();
            outPut.close();
            conn.close();
            uStream.close();

        } catch (Exception e) {
            System.err.println("Problem while downloading " + url);
            e.printStackTrace();
            return null;
        } finally {
            if (conn != null) {
                try {

                    conn.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (uStream != null) {
                try {
                    uStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            try {
                if (outPut != null) {
                    outPut.close();
                }
                if (gzOutPut != null) {
                    gzOutPut.close();
                }
            } catch (IOException e) {
            }
        }
        System.out.println("Writing to " + destination);

        copy(tempFile, destination);

        return destination;
    }

    public static String getFilePrefix(File f) {
        String fileName = f.getName();
        String fname = "";

        int mid = fileName.indexOf(".");
        fname = fileName.substring(0, mid);

        return fname;
    }

    public static String getFileExtension(File f) {
        String fileName = f.getName();
        //String fname="";
        String ext = "";
        int mid = fileName.lastIndexOf(".");
        //fname=fileName.substring(0,mid);
        ext = fileName.substring(mid + 1, fileName.length());
        //System.out.println("File name ="+fname);
        //System.out.println("Extension ="+ext);
        return ext;
    }

    /** Copy the content of file A to B
     * 
     * @param src
     * @param dst
     * @throws IOException
     */
    public static void copy(File src, File dst) throws IOException {

        InputStream in = new FileInputStream(src);
        OutputStream out = new FileOutputStream(dst);

        // Transfer bytes from in to out
        byte[] buf = new byte[1024];
        int len;
        while ((len = in.read(buf)) > 0) {
            out.write(buf, 0, len);
        }
        in.close();
        out.close();
    }
}

Related

1. downloadFileAndRetry(final File file, final URL url, final int retry)
2. downloadFileFromInternet(String remoteUrl)
3. downloadFileFromUrl(String urlPath, File file)
4. downloadFileFromWeb(URL resourceURL, String fullPath)
5. downloadFileFromWebserver(String fileUrl, String storageLocation)
6. downloadFileToGivenNameElseExtension( URLConnection urlConnection, String fileName)
7. downloadFromURL(String url)
8. downloadFromUrl(String urlString, PrintStream logger)
9. downloadFromUrl(URL url, String localFilename)