调整图像文件大小

Question

In Java I am copying an image file from one location to another . The program is executing properly, but I want the destination file size to be different from the source file size. Is there any other way to resize the file at the new location? I am using the following code:

public class NewJFrame extends javax.swing.JFrame {

    public NewJFrame() {
        initComponents();
    }

    public static void copyFile(File sourceFile, File destFile)
            throws IOException {
        if (!destFile.exists()) {
            destFile.createNewFile();
        }

        FileChannel source = null;
        FileChannel destination = null;
        try {
            source = new FileInputStream(sourceFile).getChannel();
            destination = new FileOutputStream(destFile).getChannel();

            // previous code: destination.transferFrom(source, 0, source.size());
            // to avoid infinite loops, should be:
            long count = 0;
            long size = source.size();
            while ((count += destination.transferFrom(source, count, size
                    - count)) < size)
                ;
        } finally {
            if (source != null) {
                source.close();
            }
            if (destination != null) {
                destination.close();
            }
        }
    }

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        try {
            File sourceFile = new File(
                    "d:/adesh/golden_temple_amritsar_india-normal.jpg");

            File destFile = new File(
                    "d:/adesh2/golden_temple_amritsar_india-normal.jpg");

            copyFile(sourceFile, destFile);
        } catch (Exception ex) {
        }

    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {

        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new NewJFrame().setVisible(true);
            }
        });
    }

    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
}

Answer 1

Here is the code for resizing the image as per your specification. Inside the copyFile method,

int width=100,height=75; /* set the width and height here */

BufferedImage inputImage=ImageIO.read(sourceFile);

BufferedImage outputImage=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

Graphics2D g=outputImage.createGraphics();

g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BICUBIC);

g.clearRect(0, 0, width, height);

g.drawImage(inputImage, 0, 0, width, height, null);

g.dispose();

ImageIO.write(outputImage,"jpg",destFile); /* first parameter is the object of the BufferedImage, second parameter is the type of image that you are going to write, you can use jpg, bmp, png etc and the third parameter is the destination file object. */