I am trying to open an image file that is packaged in a .jar file using the default image viewer of the computer on which i run my program.
I have found numerous answers about how to access files that are packaged in a jar using InputStream but how can i open those files using that InputStream?
InputStream imageStream = Test.class.getClass().getResourceAsStream("/test/DSC_6283.jpg");
I can convert this into an Image, ImageIcon or a BufferedImage but how to i further open the image in the default image viewer?
My class name is 'Test' and the image i am trying to access is C:\Users\Pranav\Documents\NetBeansProjects\Test\src\test\DSC_6283.jpg
Any help would be appreciated.
Pure java:
public static void main(String... args) throws IOException {
InputStream imageStream = Test.class.getClass().getResourceAsStream("/test/DSC_6283.jpg");
Path path = Files.createTempFile("DSC_6283", ".jpg");
try (FileOutputStream out = new FileOutputStream(path.toFile())) {
byte[] buffer = new byte[1024];
int len;
while ((len = imageStream.read(buffer)) != -1) {
out.write(buffer, 0, len);
}
} catch (Exception e) {
// TODO: handle exception
}
Desktop.getDesktop().open(path.toFile());
}
Edit:
byte[] buffer = new byte[1024]; //allocate an array of bytes to use as a buffer. 1024 bytes in this case
int len; //a variable to record the number of bytes actually read from the stream each loop
while ((len = imageStream.read(buffer)) != -1) { //InputStream.read(byte[]) reads bytes from the stream and places them into the buffer. It returns the number of bytes placed into the buffer, or -1 if there is nothing more to read. We store that result in len, and evaluate if we should stop looping (ie if the return is -1)
out.write(buffer, 0, len); //write to the output file, from the buffer, starting at position 0, through the number of bytes read
Note, this is boilerplate. I stole this version from Easy way to write contents of a Java InputStream to an OutputStream
Save the image locally (ex. c:\my_image.jpg), which is not in the .jar file
Use Runtime.getRuntime().exec("cmd your_command_here_to_open_image");
here is a link for cmd command on windows: http://www.sevenforums.com/software/180378-where-windows-photo-viewer-default-location.html
Related
I'm trying to download some images provided by a hoster. This is the method I use:
public static void downloadImage(String imageLink, File f) throws IOException
{
URL url = new URL(imageLink);
byte[] buffer = new byte[1024];
BufferedInputStream in = new BufferedInputStream(url.openStream(), buffer.length);
BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(f), buffer.length);
while (in.read(buffer) > 0)
out.write(buffer);
out.flush();
out.close();
in.close();
}
However, the file turn out too big. 5MB for a 80x60 jpg is too much in my opinion.
What could be the cause of this?
You are doing things wrong here: read() returns the number of bytes that were really read; thus you have to write exactly that number from your buffer array into your output stream.
Your code is corrupting your output; and simply writing out a buffer array ... that mostly consists of 0s!
Instead do something like:
int bytesRead;
while ( ( bytesRead = in.read(buffer)) > 0) {
byte outBuffer[] = new byte[bytesRead];
... then use arraycopy to move bytesRead bytes
out.write(outBuffer);
}
( this is meant as inspiration to get you going, more pseudo like than real code )
I am trying to write a simple server that uses sockets and reads images from disc when it receives http request from browser.
I am able to receive the request, read the image from disc and pass it to the browser (the browser then automatically downloads the image). However, when I try to open the downloaded image, it says:
Could not load image 'img.png'. Fatal error reading PNG image file: Not a PNG file
The same goes for all other types of extensions (jpg, jpeg, gif etc...)
Could you help me out and tell me what am I doing wrong? I suspect that there might be something wrong with the way I read the image or maybe some encoding has to be specified?
Reading the image from disc:
// read image and serve it back to the browser
public byte[] readImage(String path) {
File file = new File(FILE_PATH + path);
try {
BufferedImage image = ImageIO.read(file); // try reading the image first
// get DataBufferBytes from Raster
WritableRaster raster = image.getRaster();
DataBufferByte data = (DataBufferByte) raster.getDataBuffer();
return data.getData();
} catch (IOException ex) {
// handle exception...
}
return ("Could not read image").getBytes();
}
Writing the data via socket:
OutputStream output = clientSocket.getOutputStream();
output.write(result);
In this case, the result contains the byte array produced by the readImage method.
EDIT: second try with reading the image as normal file
FileReader reader = new FileReader(file);
char buf[] = new char[8192];
int len;
StringBuilder s = new StringBuilder();
while ((len = reader.read(buf)) >= 0) {
s.append(buf, 0, len);
byte[] byteArray = s.toString().getBytes();
}
return s.toString().getBytes();
You may use ByteArrayOutputStream, like,
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ImageIO.write(image, "jpg", byteArrayOutputStream);
and then you can write to socket as,
outputStream.write(byteArrayOutputStream.toByteArray());
I am currently writing a client-server program that would allow me to upload a file from the client to the server. However, when I try this the file becomes corrupt and it appears not all the bytes are being transferred. Can someone tell me why this is happening? Thanks.
Here is part of the client code:
System.out.println("What file would you like to upload?");
String file=in.next();//get file name
outToServer.writeUTF(file);//send file name to server
File test= new File(file);//create file
byte[] bits = new byte[(int) test.length()]; //byte array to store file
FileInputStream fis= new FileInputStream(test); //read in file
//write bytes into array
int size=(int) test.length();//size of array
outToServer.write(size);//send size of array to Server
fis.read(bits);//read in byte values
fis.close();//close stream
outToServer.write(bits, 0, size);//writes bytes out to server
And here is the server code:
String filename= inFromClient.readUTF();//read in file name that is being uploaded
int size=inFromClient.read(); //read in size of file
byte[] bots=new byte[size]; //create array
inFromClient.read(bots); //read in bytes
FileOutputStream fos=new FileOutputStream(filename);
fos.write(bots);
fos.flush();
fos.close();
String complete="Upload Complete.";
outToClient.writeUTF(complete);
Try and use Java 7's Files.copy().
On the client side:
final Path source = Paths.get(file);
Files.copy(source, outToServer);
On the server side:
final Path destination = Paths.get(file);
Files.copy(inFromClient, destination);
See the javadoc for Files.
Usual mistake. You're assuming that read() fills the buffer. It isn't obliged to do that. See the Javadoc.
The canonical way to copy streams in Java is as follows:
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
Use this at both ends. You don't need a buffer the size of the file either. This works for any byte array with one or more elements.
I want to download a HTTP query with java, but the file I download has an undetermined length when downloading.
I thought this would be quite standard, so I searched and found a code snippet for it: http://snipplr.com/view/33805/
But it has a problem with the contentLength variable. As the length is unknown, I get -1 back. This creates an error. When I omit the entire check about contentLength, that means I always have to use the maximum buffer.
But the problem is that the file is not ready yet. So the flush gets only partially filled, and parts of the file get lost.
If you try downloading a link like http://overpass-api.de/api/interpreter?data=area%5Bname%3D%22Hoogstade%22%5D%3B%0A%28%0A++node%28area%29%3B%0A++%3C%3B%0A%29+%3B%0Aout+meta+qt%3B with that snippet, you'll notice the error, and when you always download the maximum buffer to omit the error, you end up with a corrupt XML file.
Is there some way to only download the ready part of the file? I would like if this could download big files (up to a few GB).
This should work, i tested it and it works for me:
void downloadFromUrl(URL url, String localFilename) throws IOException {
InputStream is = null;
FileOutputStream fos = null;
try {
URLConnection urlConn = url.openConnection();//connect
is = urlConn.getInputStream(); //get connection inputstream
fos = new FileOutputStream(localFilename); //open outputstream to local file
byte[] buffer = new byte[4096]; //declare 4KB buffer
int len;
//while we have availble data, continue downloading and storing to local file
while ((len = is.read(buffer)) > 0) {
fos.write(buffer, 0, len);
}
} finally {
try {
if (is != null) {
is.close();
}
} finally {
if (fos != null) {
fos.close();
}
}
}
}
If you want this to run in background, simply call it in a Thread:
Thread download = new Thread(){
public void run(){
URL url= new URL("http://overpass-api.de/api/interpreter?data=area%5Bname%3D%22Hoogstade%22%5D%3B%0A%28%0A++node%28area%29%3B%0A++%3C%3B%0A%29+%3B%0Aout+meta+qt%3B");
String localFilename="mylocalfile"; //needs to be replaced with local file path
downloadFromUrl(url, localFilename);
}
};
download.start();//start the thread
My application is unable to transfer data properly over a socket connection and write it to a file properly. Files over about 65,535 bytes get corrupted and are no longer recognized by the programs designed to run them.
I have been able to send small .doc and .txt files successfully, but .mp3 .wmv .m4a .avi and just about anything else does not work. Neither do larger docs.
I have looked all over the internet for a solution to this problem. I have repeatedly tweaked the I/O code to fix the problem but it still doesn't work! Here is the I/O code in the super class that handles sending and receiving files. If you need anymore information/other parts of code, let me know.
protected void sendFile() throws IOException {
byte[] bytes = new byte[(int) file.length()];
buffin = new BufferedInputStream(new FileInputStream(file));
int bytesRead = buffin.read(bytes,0,bytes.length);
System.out.println(bytesRead);
out = sock.getOutputStream();
out.write(bytes,0,fileBytes);
out.flush();
out.close();
}
protected void receiveFile() throws IOException {
byte[] bytes = new byte[fileBytes];
in = sock.getInputStream();
for(int i=0;i<fileBytes;i++) {
in.read(bytes);
}
fos = new FileOutputStream("/Datawire/"+fileName);
buffout = new BufferedOutputStream(fos);
buffout.write(bytes,0,fileBytes);
buffout.flush();
buffout.close();
}
UPDATED CODE (that works):
protected void sendFile() throws IOException {
if((file.length())<63000) {
byte[] bytes = new byte[(int)file.length()];
buffin = new BufferedInputStream(new FileInputStream(file));
buffin.read(bytes,0,bytes.length);
out = sock.getOutputStream();
out.write(bytes,0,bytes.length);
out.close();
} else {
byte[] bytes = new byte[32000];
buffin = new BufferedInputStream(new FileInputStream(file));
out = sock.getOutputStream();
int bytesRead;
while((bytesRead = buffin.read(bytes))>0) {
out.write(bytes,0,bytesRead);
}
out.close();
}
}
protected void receiveFile() throws IOException {
if(fileBytes<63000) {
byte[] bytes = new byte[32000];
in = sock.getInputStream();
System.out.println(in.available());
in.read(bytes,0,fileBytes);
fos = new FileOutputStream("/Datawire/"+fileName);
buffout = new BufferedOutputStream(fos);
buffout.write(bytes,0,bytes.length);
buffout.close();
} else {
byte[] bytes = new byte[16000];
in = sock.getInputStream();
fos = new FileOutputStream("/Datawire/"+fileName);
buffout = new BufferedOutputStream(fos);
int bytesRead;
while((bytesRead = in.read(bytes))>0) {
buffout.write(bytes,0,bytesRead);
}
buffout.close();
}
}
The issue is that you are sending only chunks of it. That is, you are only sending 64k of the file ever. If the file is ever larger then 64k the other end will never see it.
You want to continously read from the BufferedInputStream until the read() returns either less then the length or -1.
Your code is completely wrong. This is how to copy a stream in Java:
int count;
byte[] buffer = new byte[8192]; // more if you like but no need for it to be the entire file size
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
You should use this both when sending the file and when receiving the file. At present your sending method hopes that the entire file fits into memory; fits into INTEGER_MAX bytes; and is read in one chunk by the read method, without even checking the result. You can't assume any of those things. Your receive method is complete rubbish: it just keeps overwriting the same array, again without checking any read() results.
EDIT: Your revised code is just as bad, or worse. You are calling read() to check for EOS and then throwing that byte away, and then calling read() again and throwing away the read count it returns. You pointlessly have a different path for files < 64000, or 63000, or whatever it is, that has zero benefit except to give you two code paths to test, or possibly four, instead of one. The network only gives you 1460 bytes at a time at best anyway so what is the point? You already have (a) a BufferedInputStream with a default buffersize of 8192, and (b) my code that uses a byte[] buffer of any size you like. My code above works for any amount of data in two lines of executable code. Yours is 20. QED.
I suggest that you use some good library to read and write file contents as well as socket read/write. For example Apache Commons IO. If you insist on writig code yourself, do it smaller chunks rather than the whole file at once.
You have to consider that InputStream.read returns the number of bytes read which may be less than the total number of bytes in the file.
You would probably be better off just letting something like CopyUtils.copy take care of this for you.
You need to loop until bytesRead < 0. You need to make sure that fileBytes is => than the transferred file.
protected void receiveFile() throws IOException {
byte [] bytes = new byte [fileBytes];
InputStream is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream("/Datawire/"+fileName);
BufferedOutputStream bos = new BufferedOutputStream(fos);
int bytesRead = is.read(bytes,0,bytes.length);
int current = bytesRead;
do {
bytesRead =
is.read(bytes, current, (bytes.length-current));
if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);
bos.write(bytes, 0 , current);
bos.flush();
bos.close();
}