用java程序使图片等比缩放

public static void main(String args[]) {
try {
double ratio = 0.0; //缩放比例
String filePath="d://sssss.jpeg";
int width=475;
int height=350;
File f = new File(filePath);
BufferedImage bi = ImageIO.read(f);
Image itemp = bi.getScaledInstance(width, height, bi.SCALE_SMOOTH);
//计算比例
if ((bi.getHeight() > height) || (bi.getWidth() > width)) {
if (bi.getHeight() > bi.getWidth()) {
ratio = (new Integer(height)).doubleValue() / bi.getHeight();
} else {
ratio = (new Integer(width)).doubleValue() / bi.getWidth();
}
AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(ratio, ratio), null);
itemp = op.filter(bi, null);
}

BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
g.setColor(Color.white);
g.fillRect(0, 0, width, height);
if (width == itemp.getWidth(null))
g.drawImage(itemp, 0, (height - itemp.getHeight(null)) / 2, itemp.getWidth(null), itemp.getHeight(null), Color.white, null);
else
g.drawImage(itemp, (width - itemp.getWidth(null)) / 2, 0, itemp.getWidth(null), itemp.getHeight(null), Color.white, null);
g.dispose();
itemp = image;
File f2 = new File("d://ss.jpeg");
ImageIO.write((BufferedImage) itemp, "jpeg", f2);
} catch (IOException e) {
e.printStackTrace();
}
}