Reading binary content from HTTP?

Question

As long as i read text (ascii) data from a HttpURLConnection, the resulting stream (written to a file) is okay (readable). but when i want to read a PDF file with the same code, the written output file is not readable with the Acrobat reader (file type not supported or file corrupted):
                //read data from HTTP server:
                InputStream is = null;
                HttpURLConnection con = null;
                try {
                    System.out.print(key+": connecting ...");
                    con = (HttpURLConnection) url.openConnection();
                    if (con instanceof HttpsURLConnection) { //HTTPS URL?
                        //avoid "java.io.IOException: HTTPS hostname wrong:  should be <217.5.135.142>"
                        ((HttpsURLConnection) con).setHostnameVerifier(new HostnameVerifier() {
                            public boolean verify(String hostname, SSLSession session) {
                                return true;
                    System.out.print(" reading ...");
                    try {
                        is = con.getInputStream();
                        try { //in case input stream is compressed via GZIP:
                            is = new GZIPInputStream(is);
                        } catch (IOException ioe) {
                            //ignore (input stream is not GZIP compressed)
                    } catch (IOException ioe) {
                        System.err.println("Error getting input stream. HTTP return code: "+con.getResponseCode()+" ("+con.getResponseMessage()+"). "+ ioe);
                        return;
                    IOUtils.writeStream(is, os);
                } catch (Exception e) {
                    System.err.println("\nError getting content from URL: " + e);
                    return;
                } finally {
                    if (is != null) { try { is.close(); } catch (IOException ioe) { ioe.printStackTrace(System.err); } }
                    if (con != null) { try { con.disconnect(); } catch (Exception e) { e.printStackTrace(System.err); } }
                    if (os != null) { try { os.close(); } catch (IOException ioe) { ioe.printStackTrace(System.err); } }
                }when i open the written pdf file with a text editor, i noticed the the first line is
DF-1.4
so, the first character "P" is missing. but even when i add the "P" in the text file and save it, Acrobat Reader shows the same error.
is there another way to load binary data from a HttpUrlConnection and/or write it to a file?

Answer 1

yes, it's simple and works with text/ascii content from URLS:
     public static void writeStream(InputStream inputStream, OutputStream outputStream) throws IOException {
        if (inputStream != null && outputStream != null) {
            int count;
            byte[] bytes = new byte[128];
            while ((count = inputStream.read(bytes, 0, bytes.length)) != -1) { //use full read() method for GZIPInputStream to be treated correctly
                outputStream.write(bytes, 0, count);     
    }//writeStream()it's pdf content that doesn't work (completely). the first two characters "%P" are mssing. if i add them by hand (e.g. my writting this two characters to the outputSTream before continuing with the PDF content), the resulting file is okay (can be read by acrobat reader).
perhaps, some inner Java class misinterpret the "%P" characters as a special code sequence?