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How to save BufferedImage to FastDFS in Java?

I have an image and I do somethings with it, finally I get an BufferedImage object(the sub image of original image), now I want to save the sub image to FastDFS without save it in my local, what should I do?
I have already save sub image as file to my local, but I don't want to do like this, because it makes waste.
String oriPicPathInFastDFS = "http://127.0.0.1/xx/xx/xx/xx";
BufferedImage image = null;
try {
image = ImageIO.read(new URL(oriPicPathInFastDFS));
} catch (IOException e) {
e.printStackTrace();
}
// do something
// this is the sub image that I want to save to FastDFS
BufferedImage subImage = image.getSubimage(5, 5, 5, 5);
// these code can save the sub image to my local and then upload to fastDFS
String localPath = "/home/xx/x/xx.jpg";
File detectionFile = new File(localPath);
try {
detectionFile.createNewFile();
ImageIO.write(subImage, "jpg", detectionFile);
} catch (IOException e) {
e.printStackTrace();
}
// upload to fast dfs
I want to upload the subImage to fastDFS without save it to my local.

Fine, I got a method to solve this question.
// change the BufferedImage to byte[]
ByteArrayOutputStream out = new ByteArrayOutputStream();
try {
boolean flag = ImageIO.write(sunImage, "jpg", out);
} catch (IOException e) {
e.printStackTrace();
}
byte[] byteArray = out.toByteArray();
// then save the byteArray to fast DFS

Checking if an image is blank in Java

I'm currently working on a dynamic Animation Loader for Characters in a game and for that I'm in need of detecting if the current frame is completely blank in order to stop loading more sprites.
This is what I'm currently using to find out if the current image is blank:
public static boolean isBlankImage(BufferedImage b) {
byte[] pixels1 = getPixels(b);
byte[] pixels2 = getPixels(getBlankImage(b.getWidth(), b.getHeight()));
return Arrays.equals(pixels1, pixels2);
}
private static BufferedImage getBlankImage(int width, int height) {
return new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
}
private static byte[] getPixels(BufferedImage b) {
byte[] pixels = ((DataBufferByte) b.getRaster().getDataBuffer()).getData();
return pixels;
}
However, as soon as I run it, I get this annoying error:
Exception in thread "Thread-0" java.lang.ClassCastException:
java.awt.image.DataBufferInt cannot be cast to java.awt.image.DataBufferByte
I've tried switching the casting type but all I get in return is:
Exception in thread "Thread-0" java.lang.ClassCastException:
java.awt.image.DataBufferByte cannot be cast to java.awt.image.DataBufferInt
I've searched all over the place for an answer to no avail, so here's my question: Is there a better functional way to check if an image is fully transparent ?
Any help will be greatly appreciated.

The method must be return a byte array, you are trying convert a DataBuffer in a DataBufferByte.
I have changed the name getPixels to getByteArray. Since it is not the same.
Try this:
private static byte[] getByteArray(BufferedImage img) {
byte[] imageInByte = null;
String format = "jpeg"; //Needs a image TYPE
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(img, format, baos);
baos.flush();
imageInByte = baos.toByteArray();
baos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return imageInByte;
}

The blank image's DataBuffer is indeed an instance of DataBufferInt while your original image has a buffer of type DataBufferByte.
You should create your empty image based on the type of the image to compare with:
private static BufferedImage getBlankImage(int width, int height, int type) {
return new BufferedImage(width, height, type);
}
and call it this way:
getBlankImage(b.getWidth(), b.getHeight(), b.getType())
Notice that in terms of performance and memory usage it may be better to create the empty image only once (or once for each image type which may occur).
Probably the image type and size are constant and written wherever the actual images are created.
Now you have a proper empty image and may test its equality as in Is there a simple way to compare BufferedImage instances?:
public static boolean compareImages(BufferedImage imgA, BufferedImage imgB) {
int width = imgA.getWidth();
int height = imgA.getHeight();
// Loop over every pixel.
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
// Compare the pixels for equality.
if (imgA.getRGB(x, y) != imgB.getRGB(x, y)) {
return false;
}
}
}
return true;
}

How to upload bufferedImage without storing it in user's system?

I am a beginner in java, and I am trying to write a simple screen-capture program. I wrote a simple SWING desktop app with a button and a text-field, and what I am trying to do is, when a user clicks that button the app takes a snapshot of the screen using awt.Robot, and sends that image and the text to a PHP script on my server.
My snapshot function so far is:
private void takeSnapShot(){
try {
Robot robot = new Robot();
Rectangle area = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
BufferedImage bufferedImage = robot.createScreenCapture(area);
//Try to save the captured image
try {
File file = new File("screenshot_full.png");
ImageIO.write(bufferedImage, "png", file);
} catch (IOException ex) {
Logger.getLogger(ScrCaptFrm.class.getName()).log(Level.SEVERE, null, ex);
}
} catch (AWTException ex) {
Logger.getLogger(ScrCaptFrm.class.getName()).log(Level.SEVERE, null, ex);
}
}
As you can see it's fairly simple so far, however I am not sure how to send that image to my PHP script without actually storing the image on user's PC.
Oh and I am using apache httpClient library for communicating to the web server. For the text I guess I can pass it in the URL as a get query, but I am not sure what to do about the image.

ImageIO.write can to an OutputStream of your choice.
So if you don't want to write the image to a File, you can simply write it to a different stream instead...
For example...
OutputStream os = null;
try {
Robot robot = new Robot();
Rectangle area = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
BufferedImage bufferedImage = robot.createScreenCapture(area);
//Try to save the captured image
try {
os = ...;
ImageIO.write(bufferedImage, "png", os);
} catch (IOException ex) {
Logger.getLogger(ScrCaptFrm.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
os.close();
} catch (Exception exp) {
}
}
} catch (AWTException ex) {
Logger.getLogger(ScrCaptFrm.class.getName()).log(Level.SEVERE, null, ex);
}
Of course, I have no idea where you're sending the data, so you'll need to define the OutputStream yourself.
If you have the memory for it, you could write it a ByteArrayOutputStream and then write this to whatever output stream you need in the future...

To slightly modify your existing method, perhaps you could use a temporarily file and then delete it when you are finished with it. Perhaps it might look something like:
private void takeSnapShot(){
try {
Robot robot = new Robot();
Rectangle area = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
BufferedImage bufferedImage = robot.createScreenCapture(area);
//Try to save the captured image
try {
File file = File.createTempFile(Long.toString(System.currentTimeMillis()), ".png");
ImageIO.write(bufferedImage, "png", file);
//send image
file.delete();
} catch (IOException ex) {
Logger.getLogger(ScrCaptFrm.class.getName()).log(Level.SEVERE, null, ex);
}
} catch (AWTException ex) {
Logger.getLogger(ScrCaptFrm.class.getName()).log(Level.SEVERE, null, ex);
}
}
Another alternative would be to construct an int[][] from your BufferedImage which will hold the RGB values for every pixel of the image:
public int[][] getColors(final BufferedImage image){
assert image != null;
final int[][] colors = new int[image.getWidth()][image.getHeight()];
for(int x = 0; x < colors.length; x++)
for(int y = 0; y < colors[x].length; y++)
colors[x][x] = image.getRGB(x, y);
return colors;
}
I am a little unsure about what you hope to achieve; What do you plan on doing with the image?

Why don't you make this a WebsService and let your PHP consume it? You could send the binary data through the WebsService using some sort of Base64 encoder.
You could do this to get the bytes of the BufferedImage:
byte[] binaryData = ((DataBufferByte) bufferedImage.getData().getDataBuffer()).getData();

How to control (move) the mouse cursor?

How do I move the mouse cursor (windows) with Java?
I have a pair of values constantly being updated. I want to use them to control the cursor.

Robot.mouseMove(x,y)
As mentioned in:
https://stackoverflow.com/a/2941373/1150918 by OscarRyz.

You will need to use the Robot class.
Robot r = null;
try {
r = new Robot();
} catch (AWTException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
r.mouseMove(x, y);//x is the horizontal position on the screen, y is the vertical

Can not open file using fullpath in java

Here is the code I have now:
File file= new File("C:\Documents and Settings\vasanth\Desktop\s.PNG");
BufferedImage image;
try {
image = ImageIO.read(file);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Raster raster = image.getRaster();
BufferedImage image2 = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB);
WritableRaster raster2 = image2.getRaster();
BufferedImage image3 = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB);
WritableRaster raster3 = image3.getRaster();
Should I keep the image that I am using here? Even though I have specified the full path to the image file, I still get an error.

Use double slash in java strings. Single slash is considered a character escape sequence.
So you should open the file like so:
File file= new File("C:\\Documents and Settings\\vasanth\\Desktop\\s.PNG");

Along with what Ivaylo said, have a look at this portion of code:
BufferedImage image;
try {
image = ImageIO.read(file);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Raster raster = image.getRaster();
Have you considered what happens if you have an exception assigning image? You will call a method on a null object and that will kill your app entirely with a NullPointerException.
You need to stop whatever you wanted to do with the image if an exception occurs. You can put all of it within the try...catch block to fix this.