WGET download happens faster when executed through command line and slowly when executed through Java code

问题

I am downloading a file using WGET through a java code, which takes around 10 mins to download 20 MB file. But on executing the wget download through command line, the same file gets downloaded in 7 seconds at 10MbPs speed. Does anyone know why this is? How can I improve my Java code?

Below is the code I have used to download a file using WGET. It takes around 10 minutes to download a 20 MB file. But when I run the wget command through the command line, it happens in seconds!!

  import java.io.BufferedReader;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.net.URLConnection;



 public class WGETServer
{



public File download(URL sourceurl, String username, String password, String fileName)
{
    //System.out.println("WGET download() is starting ...");

    File file = null;
    URLConnection urlConnection = null;
    BufferedReader reader = null;
    FileOutputStream outputStream = null;
    try {

        urlConnection = sourceurl.openConnection();

            String userNameAndPassword = username +":"+ password;
            String encoding = new sun.misc.BASE64Encoder().encode (userNameAndPassword.getBytes());
            //The line which is supposed to add authorization data 
            urlConnection.setRequestProperty ("Authorization", "Basic " + encoding);

        reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
    }
    catch (IOException e) {
        System.err.println("Internet connection failure or invalid Username/Password.");
        return null;
    }
    try {
        file = new File("file path");
        outputStream = new FileOutputStream(file);
        int character;
        while((character = reader.read()) != -1)
        {
            outputStream.write(character);
        } 
        outputStream.flush();
        outputStream.close();
        reader.close();
    } catch (IOException e) {
        System.err.println(e.getMessage());
        return null;
    }
    System.out.println("downloading completed");
    return file;

}



public static void main(String args[]) throws MalformedURLException
{
    URL sourceurl = new URL("https:blablabla");
    String username = "username";
    String password = "password";
    String filename = "filename";
    WGETServer WGETdownload = new WGETServer();
    WGETdownload.download(sourceurl, username, password, filename);
}

}

回答1:

Wrap the FileOutputStream with a BufferedOutputStream.

new BufferedOutputStream(new FileOutputStream(...))

Otherwise each and every character written is synchronized to disk by the underlying operating system which is a time consuming process. This is why buffering is so important.

回答2:

You have buffered reader (Good) but then you write the content char by char to the disk (BAD). That kills your performance. It's not the reading, it's the writing.

来源：https://stackoverflow.com/questions/9922758/wget-download-happens-faster-when-executed-through-command-line-and-slowly-when

标签

java

wget