使用java.awt包 对图片进行大小调整

import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.Transparency; import java.awt.RenderingHints.Key; import java.awt.image.BufferedImage; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.util.HashMap; import java.util.Map; import org.apache.commons.fileupload.util.Streams; import com.sun.image.codec.jpeg.JPEGCodec; import com.sun.image.codec.jpeg.JPEGImageEncoder; public class TranscodeDemo { private static int widht = 400; private static int height = 400; /** * @param args * @throws IOException */ public static final Map<Key, Object> RENDERING_HINTS = new HashMap<Key, Object>(); public static void init(){ RENDERING_HINTS.put(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY); RENDERING_HINTS.put(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY); RENDERING_HINTS.put(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC); RENDERING_HINTS.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY); RENDERING_HINTS.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); } public static void main(String[] args) throws IOException { init(); byte[] imageBytes = null; File file = new File("c:/sample/fff.jpg"); imageBytes = readStreamIntoMemory(new FileInputStream(file)); BufferedImage img = javax.imageio.ImageIO.read(new ByteArrayInputStream(imageBytes)); img = scaledImage(img, widht, height, true, RENDERING_HINTS); FileOutputStream fos = new FileOutputStream("c:/sample/fff_1.jpg"); JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(fos); encoder.encode(img); fos.close(); } public static byte[] readStreamIntoMemory(InputStream in) throws IOException { ByteArrayOutputStream baos = new ByteArrayOutputStream(); Streams.copy(in, baos, true); return baos.toByteArray(); } public static BufferedImage scaledImage(BufferedImage img, int targetWidth, int targetHeight, boolean higherQuality, Map renderingHints){ int width = img.getWidth(); int height = img.getHeight(); if (width != height) { if (width > height) { targetHeight = (int) (((double) targetWidth * (double) height) / (double) width); } else { targetWidth = (int) (((double) targetHeight * (double) width) / (double) height); } } int type = (img.getTransparency() == Transparency.OPAQUE) ? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB; BufferedImage scaledImg = (BufferedImage) img; int w, h; if (higherQuality) { w = img.getWidth(); h = img.getHeight(); } else { w = targetWidth; h = targetHeight; } do { if (w < targetWidth && h < targetHeight) { break; } if (higherQuality && w > targetWidth) { w /= 2; if (w < targetWidth) { w = targetWidth; } } if (higherQuality && h > targetHeight) { h /= 2; if (h < targetHeight) { h = targetHeight; } } BufferedImage tmp = new BufferedImage(w, h, type); Graphics2D g2 = tmp.createGraphics(); g2.setRenderingHints(renderingHints); g2.drawImage(scaledImg, 0, 0, w, h, null); g2.dispose(); scaledImg = tmp; } while (w != targetWidth || h != targetHeight); return scaledImg; } }