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();  
               }  
        }