How to get PDF file from web using java streams

Question

I need to download PDF file from web, for example http://www.math.uni-goettingen.de/zirkel/loesungen/blatt15/loes15.pdf this link. I have to do it using Streams. With images it works fine by me :

public static void main(String[] args) {
        try {           
                //get the url page from the arguments array
                String arg = args[0];
                URL url = new URL("https://cs7065.vk.me/c637923/v637923205/25608/AD8WhOSx1ic.jpg");

                try{
                    //jpg
                    InputStream in = new BufferedInputStream(url.openStream());
                    ByteArrayOutputStream out = new ByteArrayOutputStream();
                    byte[] buf = new byte[131072];
                    int n = 0;
                    while (-1!=(n=in.read(buf)))
                    {
                       out.write(buf, 0, n);
                    }
                    out.close();
                    in.close();
                    byte[] response = out.toByteArray();
                    FileOutputStream fos = new FileOutputStream("borrowed_image.jpg");
                    fos.write(response);
                    fos.close();
                 }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

But with PDf it does not work. What could be the problem ?

Please clarify what "does not work" means. Is the code throwing an exception? Is it generating an unreadable pdf file? Something else? — StvnBrkdll
– StvnBrkdll, Commented Dec 17, 2016 at 18:39
I fixed the syntax errors in your code, and used this url to get a sample pdf, and your code worked fine: pdf995.com/samples/pdf.pdf — StvnBrkdll
– StvnBrkdll, Commented Dec 17, 2016 at 18:48
Works for me after cleaning up the try-statements. Doesn't look that bad but for lacking doc comments, not using try-with-resource and overdoing buffering. — greybeard
– greybeard, Commented Dec 17, 2016 at 18:57

StvnBrkdll · Accepted Answer · 2016-12-17 18:48:40Z

I made minor edits to your code to fix syntax errors and, this seems to work (below). Consider placing your close() statements in a finally block.

package org.snb;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.URL;

public class PdfTester {
    public static void main(String[] args) {
        //get the url page from the arguments array

        try{
            //String arg = args[0];
            URL url = new URL("http://www.pdf995.com/samples/pdf.pdf");
            //jpg
            InputStream in = new BufferedInputStream(url.openStream());
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            byte[] buf = new byte[131072];
            int n = 0;
            while (-1!=(n=in.read(buf)))
            {
               out.write(buf, 0, n);
            }
            out.close();
            in.close();
            byte[] response = out.toByteArray();
            FileOutputStream fos = new FileOutputStream("/tmp/bart.pdf");
            fos.write(response);
            fos.close();
         }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Ran Koretzki · Accepted Answer · 2016-12-17 18:46:48Z

try this, this got the job done (and pdf is readable). see if there are any exceptions thrown when requesting the url.

public static void main(String[] args) {
        try {
            //get the url page from the arguments array
            URL url = new URL("http://www.math.uni-goettingen.de/zirkel/loesungen/blatt15/loes15.pdf");

            try {
                InputStream in = new BufferedInputStream(url.openStream());
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                byte[] buf = new byte[131072];
                int n = 0;
                while (-1 != (n = in.read(buf))) {
                    out.write(buf, 0, n);
                }
                out.close();
                in.close();
                byte[] response = out.toByteArray();
                FileOutputStream fos = new FileOutputStream("loes15.pdf");
                fos.write(response);
                fos.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

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