Java tutorial
// revised from richfaces photoalbum import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.Transparency; import java.awt.image.BufferedImage; import java.io.*; import java.util.zip.*; import javax.imageio.ImageIO; import javax.imageio.ImageReader; import javax.imageio.ImageWriter; import javax.imageio.stream.ImageInputStream; /** * Utility class for operations with file-system * */ public class FileUtils { private static final String JPEG = "jpeg"; private static final String JPG = "jpg"; private static final int BUFFER_SIZE = 4 * 1024; private static final boolean CLOCK = true; private static final boolean VERIFY = true; /** * Utility method for copying file * @param srcFile - source file * @param destFile - destination file */ public static void copyFile(File srcFile, File destFile) throws IOException { if (!srcFile.getPath().toLowerCase().endsWith(JPG) && !srcFile.getPath().toLowerCase().endsWith(JPEG)) { return; } final InputStream in = new FileInputStream(srcFile); final OutputStream out = new FileOutputStream(destFile); try { long millis = System.currentTimeMillis(); CRC32 checksum; if (VERIFY) { checksum = new CRC32(); checksum.reset(); } final byte[] buffer = new byte[BUFFER_SIZE]; int bytesRead = in.read(buffer); while (bytesRead >= 0) { if (VERIFY) { checksum.update(buffer, 0, bytesRead); } out.write(buffer, 0, bytesRead); bytesRead = in.read(buffer); } if (CLOCK) { millis = System.currentTimeMillis() - millis; System.out.println("Copy file '" + srcFile.getPath() + "' on " + millis / 1000L + " second(s)"); } } catch (IOException e) { throw e; } finally { out.close(); in.close(); } } /** * Utility method for copying directory * @param srcDir - source directory * @param dstDir - destination directory */ public static void copyDirectory(File srcDir, File dstDir) throws IOException { if (".svn".equals(srcDir.getName())) { return; } if (srcDir.isDirectory()) { if (!dstDir.exists()) { dstDir.mkdir(); } for (String aChildren : srcDir.list()) { copyDirectory(new File(srcDir, aChildren), new File(dstDir, aChildren)); } } else { copyFile(srcDir, dstDir); } } /** * Utility method for delete directory * @param dir - directory to delete * @param isInitialDelete - determine if the deleting process running at startup or on destroy of application * @return true if directory succesfully deleted */ public static boolean deleteDirectory(File dir, boolean isInitialDelete) { if (dir.isDirectory()) { if (dir.exists()) { for (File child : dir.listFiles()) { try { deleteDirectory(child, isInitialDelete); } catch (Exception e) { if (isInitialDelete) { continue; } else return false; } } } } else { if (dir.exists()) { final boolean isFileDeleted = dir.delete(); System.out.println((isFileDeleted ? "OK " : "ERROR ") + "Delete file '" + dir.getPath() + '\''); } } dir.delete(); return true; } /** * Utility method for concatenation names of collection of files * @param files - array of strings to concatenate * @return concatenated string */ public static String joinFiles(String... files) { final StringBuilder res = new StringBuilder(); for (String file : files) { res.append(file).append(File.separatorChar); } return res.substring(0, res.length() - 1); } /** * Utility method for delete file * @param file - file to delete */ public static void deleteFile(File file) { if (file.exists()) { file.delete(); } } /** * Utility method to read image from disk and transform image to BufferedImage object * @param data - relative path to the image * @param format - file prefix of the image * @return BufferedImage representation of the image * */ public static BufferedImage bitmapToImage(String data, String format) throws IOException { final InputStream inb = new FileInputStream(data); final ImageReader rdr = ImageIO.getImageReadersByFormatName(format).next(); final ImageInputStream imageInput = ImageIO.createImageInputStream(inb); rdr.setInput(imageInput); final BufferedImage image = rdr.read(0); inb.close(); return image; } /** * Utility method to write BufferedImage object to disk * @param image - BufferedImage object to save. * @param data - relative path to the image * @param format - file prefix of the image * @return BufferedImage representation of the image * */ public static void imageToBitmap(BufferedImage image, String data, String format) throws IOException { final OutputStream inb = new FileOutputStream(data); final ImageWriter wrt = ImageIO.getImageWritersByFormatName(format).next(); final ImageInputStream imageInput = ImageIO.createImageOutputStream(inb); wrt.setOutput(imageInput); wrt.write(image); inb.close(); } /** * Convenience method that returns a scaled instance of the * provided {@code BufferedImage}. * * @param img the original image to be scaled * @param targetWidth the desired width of the scaled instance, * in pixels * @param targetHeight the desired height of the scaled instance, * in pixels * @param hint one of the rendering hints that corresponds to * {@code RenderingHints.KEY_INTERPOLATION} (e.g. * {@code RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR}, * {@code RenderingHints.VALUE_INTERPOLATION_BILINEAR}, * {@code RenderingHints.VALUE_INTERPOLATION_BICUBIC}) * @param higherQuality if true, this method will use a multi-step * scaling technique that provides higher quality than the usual * one-step technique (only useful in downscaling cases, where * {@code targetWidth} or {@code targetHeight} is * smaller than the original dimensions, and generally only when * the {@code BILINEAR} hint is specified) * @return a scaled version of the original {@code BufferedImage} */ public static BufferedImage getScaledInstance(BufferedImage img, int targetWidth, int targetHeight, Object hint, boolean higherQuality) { final int type = img.getTransparency() == Transparency.OPAQUE ? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB; BufferedImage ret = (BufferedImage) img; int w; int h; if (higherQuality) { // Use multi-step technique: start with original size, then // scale down in multiple passes with drawImage() // until the target size is reached w = img.getWidth(); h = img.getHeight(); } else { // Use one-step technique: scale directly from original // size to target size with a single drawImage() call w = targetWidth; h = targetHeight; } do { if (higherQuality && w > targetWidth) { w /= 2; if (w < targetWidth) { w = targetWidth; } } if (higherQuality && h > targetHeight) { h /= 2; if (h < targetHeight) { h = targetHeight; } } final BufferedImage tmp = new BufferedImage(w, h, type); final Graphics2D g2 = tmp.createGraphics(); g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint); g2.drawImage(ret, 0, 0, w, h, null); g2.dispose(); ret = tmp; } while (w != targetWidth || h != targetHeight); return ret; } /** * Utility method for creation of directory * @param directory - directory to create * */ public static void addDirectory(File directory) { if (directory.exists()) { deleteDirectory(directory, false); } directory.mkdirs(); } }