Java URL Download downloadFile(String fileURL, String savePath)

Description

Downloads a file from a URL

License

Open Source License

Parameter

Parameter	Description
fileURL	HTTP URL of the file to be downloaded
savePath	path of the directory to save the file

Exception

Parameter	Description
IOException	an exception

Declaration

public static String downloadFile(String fileURL, String savePath) throws IOException 

Method Source Code

//package com.java2s;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

public class Main {
    /**// ww  w .j  av a2s . c om
     * Downloads a file from a URL
     *
     * @param fileURL  HTTP URL of the file to be downloaded
     * @param savePath path of the directory to save the file
     * @throws IOException
     * @author www.codejava.net
     */
    public static String downloadFile(String fileURL, String savePath) throws IOException {
        System.err.printf("Downloading %s to %s\n", fileURL, savePath);
        URL url = new URL(fileURL);
        HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
        int responseCode = httpConn.getResponseCode();

        // always check HTTP response code first
        if (responseCode == HttpURLConnection.HTTP_OK) {
            String fileName = "";
            String disposition = httpConn.getHeaderField("Content-Disposition");
            String contentType = httpConn.getContentType();
            int contentLength = httpConn.getContentLength();

            if (disposition != null) {
                // extracts file name from header field
                int index = disposition.indexOf("filename=");
                if (index > 0) {
                    fileName = disposition.substring(index + 10, disposition.length() - 1);
                }
            } else {
                // extracts file name from URL
                fileName = new File(httpConn.getURL().getPath()).getName();
            }

            //            System.out.println("Content-Type = " + contentType);
            //            System.out.println("Content-Disposition = " + disposition);
            //            System.out.println("Content-Length = " + contentLength);
            //            System.out.println("fileName = " + fileName);

            // opens input stream from the HTTP connection
            InputStream inputStream = httpConn.getInputStream();
            String saveFilePath = savePath;
            if (new File(savePath).isDirectory())
                saveFilePath = savePath + File.separator + fileName;
            String realPath;
            if (new File(saveFilePath).isFile()) {
                System.err.printf("Use cached %s instead.\n", fileName);
                realPath = saveFilePath;
            } else {
                saveFilePath += ".downloading";

                // opens an output stream to save into file
                FileOutputStream outputStream = new FileOutputStream(saveFilePath);

                int bytesRead;
                byte[] buffer = new byte[4096];
                long start = System.currentTimeMillis();
                int progress_size = 0;
                while ((bytesRead = inputStream.read(buffer)) != -1) {
                    outputStream.write(buffer, 0, bytesRead);
                    long duration = (System.currentTimeMillis() - start) / 1000;
                    duration = Math.max(duration, 1);
                    progress_size += bytesRead;
                    int speed = (int) (progress_size / (1024 * duration));
                    float ratio = progress_size / (float) contentLength;
                    float percent = ratio * 100;
                    int eta = (int) (duration / ratio * (1 - ratio));
                    int minutes = eta / 60;
                    int seconds = eta % 60;

                    System.err.printf("\r%.2f%%, %d MB, %d KB/s, ETA %d min %d s", percent,
                            progress_size / (1024 * 1024), speed, minutes, seconds);
                }
                System.err.println();
                outputStream.close();
                realPath = saveFilePath.substring(0, saveFilePath.length() - ".downloading".length());
                if (!new File(saveFilePath).renameTo(new File(realPath)))
                    throw new IOException("Failed to move file");
            }
            inputStream.close();
            httpConn.disconnect();

            return realPath;
        } else {
            httpConn.disconnect();
            throw new IOException("No file to download. Server replied HTTP code: " + responseCode);
        }
    }
}

Related

1. downloadFile(File parent, String prefix, String suffix, URL url)
2. downloadFile(File target, String urlStr)
3. downloadFile(final String url)
4. downloadFile(String fileURL, String localFileName, String destinationDir)
5. downloadFile(String fileURL, String saveDir)
6. downloadFile(String fileURL, String targetDirectory)
7. downloadFile(String url)
8. downloadFile(String url, File output)
9. downloadFile(String url, String fileName)