Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

ULRConnection(), example reading image

Posted on 1998-07-01
9
Medium Priority
?
276 Views
Last Modified: 2010-05-18
I have got the connection to an image/jpeg type now I have to draw it.  so far

      url = new URL(getCodeBase(), "current.jpg");
      urlc = url.openConnection();
      urlc.connect();
      System.out.println("Content type is " + urlc.getContentType();

Now I have to read it and build an Image.    
Anyone have an example or something to get me started?
I don't want to use getImage(URL);
Thanks in advance.
0
Comment
Question by:hank1
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 5
  • 4
9 Comments
 
LVL 6

Expert Comment

by:gadio
ID: 1224323
ude the folowing:

InputStream is = urlc.getInputStream();
// ....
// loop and read all the file through the input stream into a byte array buf[] .
// ....
Image res_image = Toolkit.getDefaultToolkit().createImage( buf );

Hope that helps.
G.
0
 
LVL 1

Author Comment

by:hank1
ID: 1224324
Back at work on Tuesday (6/7?).  Give it a try and award points then if successful.
Thanks.  Have a good 4th - if you're a yankee anyway. :)
0
 
LVL 1

Author Comment

by:hank1
ID: 1224325

Localized InputStream inside paint() to "implement" rewind.  However I get only
one good read. The stream is closed properly (As I understand it, when all references to
the stream are lost, the gc will close it anyway...right?) Next time into paint(),
I get a good InputStream (is not null) but my read throws an IOEx. with "read error".

Attempting to localize the URLConnection was a looping experience.  Paint never stopped.
0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 
LVL 6

Expert Comment

by:gadio
ID: 1224326
hank1, hope you had a happy 4th. :)
You shouldn't do IO operations inside paint, since they take a long time to finish and the UI will be frozen in that time. Instead you should prapare all you need for a paint before (or in another thread. The answer I have written before should be done outside the paint, and also I think that you should use the getInputStream() only once, loop through it, and onl then close it. Give it a try.
Regards,
G.
0
 
LVL 1

Author Comment

by:hank1
ID: 1224327
appletviewer runs this "fine".  Spin this up in nc4.05 and I get stream closed
exception after one successful read.  Hate to dump code but here it is, stripped to the
minimum.

  URL url;
  URLConnection urlc;
  Image eye;
  InputStream is;

  public void run() {
    while (true) {
      repaint();
      try {
        buildNoCacheImage();
        Thread.sleep(15L * 1000L);  // wait 15 seconds
      } catch (InterruptedException ie) {
        // ignore
      }
    }
  }

  public void buildNoCacheImage() {
    try {
      url = new URL(getCodeBase(), "current.jpg");
      urlc = url.openConnection();
      urlc.setUseCaches(false);
      urlc.connect();
      is = urlc.getInputStream();
      index = 0;
      read = 0;
      while ((read = is.read(b, index, 1000)) != -1) {
        index += read;
      }
      System.out.println("index/read " + index + "/" + read);
      is.close();
      eye = Toolkit.getDefaultToolkit().createImage(b);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  int index = 0;
  int read = 0;

0
 
LVL 1

Author Comment

by:hank1
ID: 1224328
gadio come get your points.
0
 
LVL 6

Expert Comment

by:gadio
ID: 1224329
I think I know what the problem is. I'm a bit tied up at work now, I'll try and give you an answer today or tomorrow the latest.
:-)
0
 
LVL 1

Author Comment

by:hank1
ID: 1224330
No, it works ok.  I was running into server image update activity.
The other previous problem was, like most filters, closing the inputstream
closed the URLConnection.  I just open everything up again.
Thanks for your help.  Come and get'um.
0
 
LVL 6

Accepted Solution

by:
gadio earned 300 total points
ID: 1224331
OK, I'll quote both my answers again:
-------
Use:

      InputStream is = urlc.getInputStream();
      // ....
      // loop and read all the file through the input stream into a byte array buf[] .
      // ....
      Image res_image = Toolkit.getDefaultToolkit().createImage( buf );
--------------
You shouldn't do IO operations inside paint, since they take a long time to finish and the UI will be frozen in that time. Instead you should prapare all you need for a paint before (or in another thread. The answer I have written before should be done outside the paint, and also I think that you should use the getInputStream() only once, loop through it, and onl then close it. Give it a try.
Regards,
 G.
0

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In this post we will learn different types of Android Layout and some basics of an Android App.
In this post we will learn how to make Android Gesture Tutorial and give different functionality whenever a user Touch or Scroll android screen.
Viewers will learn one way to get user input in Java. Introduce the Scanner object: Declare the variable that stores the user input: An example prompting the user for input: Methods you need to invoke in order to properly get  user input:
This theoretical tutorial explains exceptions, reasons for exceptions, different categories of exception and exception hierarchy.
Suggested Courses

618 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question