FileInputStream via getInputStream

[Billy]

I have a class wich loads data from a InputStream :

public static Image loadmap (InputStream fs)
{
....
}

When I use it with a local filename all works as excpected:

loadmap (new FileInputStream("myfile"));



Now I want to open this file from a webserver using an url as is the
following, but is seems that urlfs passed to loadmap is empty? Any
ideas?


try {
URL url = new URL("http://www.mysite/myfile");
try {
URLConnection con = url.openConnection();
con.connect();
InputStream urlfs;
urlfs = con.getInputStream();
return loadmap (urlfs);
} catch (IOException e) {System.out.println(e);}
} catch (MalformedURLException e) {System.out.println(e);}

 

[Andrew Thompson]

try {
URL url = new URL("http://www.mysite/myfile");

'404' in 'mybrowser', but.. is your server treating it as a directory?

try {
URLConnection con = url.openConnection();
con.connect();
InputStream urlfs;
urlfs = con.getInputStream();
return loadmap (urlfs);
} catch (IOException e) {System.out.println(e);}
} catch (MalformedURLException e) {System.out.println(e);}

And what, exactly are you doing with the
'java.net.UnknownHostException's?

No, don't tell me, let the (short, complete) code do the talking.
<http://www.physci.org/codes/sscce.jsp>

 

[Billy]

I can't make is "self contained" as I don't own de jar in wich
"loadmap()" resides. The server is intranet so that won't help either.

The problem is that i don't know if
con.getInputStream() results in the same datatype as
FileInputStream("myfile")

URL url = new URL("http://www.mysite/myfile");
URLConnection con = url.openConnection();
con.connect();
InputStream urlfs;
urlfs = con.getInputStream();

try {
URL url = new URL("http://www.mysite/myfile");

'404' in 'mybrowser', but.. is your server treating it as a directory?

try {
URLConnection con = url.openConnection();
con.connect();
InputStream urlfs;
urlfs = con.getInputStream();
return loadmap (urlfs);
} catch (IOException e) {System.out.println(e);}
} catch (MalformedURLException e) {System.out.println(e);}

And what, exactly are you doing with the
'java.net.UnknownHostException's?

No, don't tell me, let the (short, complete) code do the talking.
<http://www.physci.org/codes/sscce.jsp>

 

[Andrew Thompson]

I can't make is "self contained" as I don't own de jar in wich
"loadmap()" resides.

Use a 'dummy' jar.

The server is intranet so that won't help either.

Move it (the page, not the intranet)

The problem ..

No problems, just challenges.

HTH

 

[Chris Smith]

I can't make is "self contained" as I don't own de jar in wich
"loadmap()" resides. The server is intranet so that won't help either.

That is a shame. My first guess is that the problem is in loadmap().
Since it apparently works when the data is immediately available, but
not when you need to wait for a connection over a network, my guess is
that the person writing the loadmap() function is misusing the
available() method.

Try this code, and let us know if it fixes anything. Exception handling
removed for clarity.

URL url = new URL("http://www.mysite/myfile");
URLConnection con = url.openConnection();
con.connect();
InputStream urlfs = con.getInputStream();
ByteArrayOutputStream out = new ByteArrayOutputStream();
int c;
while ((c = urlfs.read()) != -1) out.write((byte) c);
urlfs.close();

return loadmap (new ByteArrayInputStream(out.toByteArray());

Not that you should put the code into production without thinking
through the consequences... but just let us know if it works.

--
www.designacourse.com
The Easiest Way To Train Anyone... Anywhere.

Chris Smith - Lead Software Developer/Technical Trainer
MindIQ Corporation

 

[Roedy Green]

public static Image loadmap (InputStream fs)
{
...
}

Your loadmap code might be making the erroneous assumption that every
read will get all the bytes it asks for.

see http://mindprod.com/jgloss/readblocking.html

 

[Roedy Green]

The problem is that i don't know if
con.getInputStream() results in the same datatype as
FileInputStream("myfile")

They DON'T result in the same type. You can find that out by dumping
inputstream.getClass()

But they DO both implement InputStream.

 

[Billy]

URL url = new URL("http://www.mysite/myfile");

URLConnection con = url.openConnection();
con.connect();
InputStream urlfs = con.getInputStream();
ByteArrayOutputStream out = new ByteArrayOutputStream();
int c;
while ((c = urlfs.read()) != -1) out.write((byte) c);
urlfs.close();
return loadmap (new ByteArrayInputStream(out.toByteArray());

out.size() gives a positive value, so I already got rid of the
java.lang.NegativeArraySizeException
Also the available() method was missing, so that has been solved (after
lots of negociating)