使用java.awt包 对图片进行大小调整

<p><textarea cols="50" rows="15" name="code" class="java">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&lt;Key, Object&gt; RENDERING_HINTS = new HashMap&lt;Key, Object&gt;();
    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 &gt; 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 &lt; targetWidth &amp;&amp; h &lt; targetHeight) {
                break;
            }
            if (higherQuality &amp;&amp; w &gt; targetWidth) {
                w /= 2;
                if (w &lt; targetWidth) {
                    w = targetWidth;
                }
            }
            if (higherQuality &amp;&amp; h &gt; targetHeight) {
                h /= 2;
                if (h &lt; 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;
}
}
</textarea></p>