设置图片等比例缩小

//-------------------------------可以将图片等比例缩小
//========还学到了获得图片的宽，高
BufferedImage im = ImageIO.read(new File("E:\\Vista.jpg")); 
width = im.getWidth(); 
  height =im.getHeight(); 


//===============================

package com.Utils;

import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;

public class ImageScale {

    private int width; 
    private int height; 
    private int scaleWidth; 
    double support = (double) 3.0; 
    double PI = (double) 3.14159265358978; 
    double[] contrib; 
    double[] normContrib; 
    double[] tmpContrib; 
    int startContrib, stopContrib; 
    int nDots; 
    int nHalfDots; 
 
    public BufferedImage imageZoomOut(BufferedImage srcBufferImage, int w, int h) { 
        width = srcBufferImage.getWidth(); 
        height = srcBufferImage.getHeight(); 
        scaleWidth = w; 
 
        if (DetermineResultSize(w, h) == 1) { 
            return srcBufferImage; 
        } 
        CalContrib(); 
        BufferedImage pbOut = HorizontalFiltering(srcBufferImage, w); 
        BufferedImage pbFinalOut = VerticalFiltering(pbOut, h); 
        return pbFinalOut; 
    } 
 
    /**
     * 决定图像尺寸
     */ 
    private int DetermineResultSize(int w, int h) { 
        double scaleH, scaleV; 
        scaleH = (double) w / (double) width; 
        scaleV = (double) h / (double) height; 
        // 需要判断一下scaleH，scaleV，不做放大操作 
        if (scaleH >= 1.0 && scaleV >= 1.0) { 
            return 1; 
        } 
        return 0; 
 
    } // end of DetermineResultSize() 
 
    private double Lanczos(int i, int inWidth, int outWidth, double Support) { 
        double x; 
 
        x = (double) i * (double) outWidth / (double) inWidth; 
 
        return Math.sin(x * PI) / (x * PI) * Math.sin(x * PI / Support) 
                / (x * PI / Support); 
 
    } // end of Lanczos() 
 
    // 
    // Assumption: same horizontal and vertical scaling factor 
    // 
    private void CalContrib() { 
        nHalfDots = (int) ((double) width * support / (double) scaleWidth); 
        nDots = nHalfDots * 2 + 1; 
        try { 
            contrib = new double[nDots]; 
            normContrib = new double[nDots]; 
            tmpContrib = new double[nDots]; 
        } catch (Exception e) { 
            System.out.println("init contrib,normContrib,tmpContrib" + e); 
        } 
 
        int center = nHalfDots; 
        contrib[center] = 1.0; 
 
        double weight = 0.0; 
        int i = 0; 
        for (i = 1; i <= center; i++) { 
            contrib[center + i] = Lanczos(i, width, scaleWidth, support); 
            weight += contrib[center + i]; 
        } 
 
        for (i = center - 1; i >= 0; i--) { 
            contrib[i] = contrib[center * 2 - i]; 
        } 
 
        weight = weight * 2 + 1.0; 
 
        for (i = 0; i <= center; i++) { 
            normContrib[i] = contrib[i] / weight; 
        } 
 
        for (i = center + 1; i < nDots; i++) { 
            normContrib[i] = normContrib[center * 2 - i]; 
        } 
    } // end of CalContrib() 

   // 处理边缘 
   private void CalTempContrib(int start, int stop) { 
       double weight = 0; 

       int i = 0; 
       for (i = start; i <= stop; i++) { 
           weight += contrib[i]; 
       } 

       for (i = start; i <= stop; i++) { 
           tmpContrib[i] = contrib[i] / weight; 
       } 

   } // end of CalTempContrib() 

   private int GetRedValue(int rgbValue) { 
       int temp = rgbValue & 0x00ff0000; 
       return temp >> 16; 
   } 

   private int GetGreenValue(int rgbValue) { 
       int temp = rgbValue & 0x0000ff00; 
       return temp >> 8; 
   } 

   private int GetBlueValue(int rgbValue) { 
       return rgbValue & 0x000000ff; 
   } 

   private int ComRGB(int redValue, int greenValue, int blueValue) { 

       return (redValue << 16) + (greenValue << + blueValue; 
   } 

   // 行水平滤波 
   private int HorizontalFilter(BufferedImage bufImg, int startX, int stopX, 
           int start, int stop, int y, double[] pContrib) { 
       double valueRed = 0.0; 
       double valueGreen = 0.0; 
       double valueBlue = 0.0; 
       int valueRGB = 0; 
       int i, j; 

       for (i = startX, j = start; i <= stopX; i++, j++) { 
           valueRGB = bufImg.getRGB(i, y); 

           valueRed += GetRedValue(valueRGB) * pContrib[j]; 
           valueGreen += GetGreenValue(valueRGB) * pContrib[j]; 
           valueBlue += GetBlueValue(valueRGB) * pContrib[j]; 
       } 

       valueRGB = ComRGB(Clip((int) valueRed), Clip((int) valueGreen), 
               Clip((int) valueBlue)); 
       return valueRGB; 

   } // end of HorizontalFilter() 

   // 图片水平滤波 
   private BufferedImage HorizontalFiltering(BufferedImage bufImage, int iOutW) { 
       int dwInW = bufImage.getWidth(); 
       int dwInH = bufImage.getHeight(); 
       int value = 0; 
       BufferedImage pbOut = new BufferedImage(iOutW, dwInH, 
               BufferedImage.TYPE_INT_RGB); 

       for (int x = 0; x < iOutW; x++) { 

           int startX; 
           int start; 
           int X = (int) (((double) x) * ((double) dwInW) / ((double) iOutW) + 0.5); 
           int y = 0; 

           startX = X - nHalfDots; 
           if (startX < 0) { 
               startX = 0; 
               start = nHalfDots - X; 
           } else { 
               start = 0; 
           } 

           int stop; 
           int stopX = X + nHalfDots; 
           if (stopX > (dwInW - 1)) { 
               stopX = dwInW - 1; 
               stop = nHalfDots + (dwInW - 1 - X); 
           } else { 
               stop = nHalfDots * 2; 
           } 

           if (start > 0 || stop < nDots - 1) { 
               CalTempContrib(start, stop); 
               for (y = 0; y < dwInH; y++) { 
                   value = HorizontalFilter(bufImage, startX, stopX, start, 
                           stop, y, tmpContrib); 
                   pbOut.setRGB(x, y, value); 
               } 
           } else { 
               for (y = 0; y < dwInH; y++) { 
                   value = HorizontalFilter(bufImage, startX, stopX, start, 
                           stop, y, normContrib); 
                   pbOut.setRGB(x, y, value); 
               } 
           } 
       } 

       return pbOut; 

   } // end of HorizontalFiltering() 

   private int VerticalFilter(BufferedImage pbInImage, int startY, int stopY, 
           int start, int stop, int x, double[] pContrib) { 
       double valueRed = 0.0; 
       double valueGreen = 0.0; 
       double valueBlue = 0.0; 
       int valueRGB = 0; 
       int i, j; 

       for (i = startY, j = start; i <= stopY; i++, j++) { 
           valueRGB = pbInImage.getRGB(x, i); 

           valueRed += GetRedValue(valueRGB) * pContrib[j]; 
           valueGreen += GetGreenValue(valueRGB) * pContrib[j]; 
           valueBlue += GetBlueValue(valueRGB) * pContrib[j]; 
           // System.out.println(valueRed+"->"+Clip((int)valueRed)+"<-"); 
           // 
           // System.out.println(valueGreen+"->"+Clip((int)valueGreen)+"<-"); 
           //System.out.println(valueBlue+"->"+Clip((int)valueBlue)+"<-"+"-->") 
           // ; 
       } 

       valueRGB = ComRGB(Clip((int) valueRed), Clip((int) valueGreen), 
               Clip((int) valueBlue)); 
       // System.out.println(valueRGB); 
       return valueRGB; 

   } // end of VerticalFilter() 

   private BufferedImage VerticalFiltering(BufferedImage pbImage, int iOutH) { 
 
       int iW = pbImage.getWidth(); 
       int iH = pbImage.getHeight(); 
       int value = 0; 
       BufferedImage pbOut = new BufferedImage(iW, iOutH, 
               BufferedImage.TYPE_INT_RGB); 

       for (int y = 0; y < iOutH; y++) { 

           int startY; 
           int start; 
           int Y = (int) (((double) y) * ((double) iH) / ((double) iOutH) + 0.5); 

           startY = Y - nHalfDots; 
           if (startY < 0) { 
               startY = 0; 
               start = nHalfDots - Y; 
           } else { 
               start = 0; 
           } 

           int stop; 
           int stopY = Y + nHalfDots; 
           if (stopY > (int) (iH - 1)) { 
               stopY = iH - 1; 
               stop = nHalfDots + (iH - 1 - Y); 
           } else { 
               stop = nHalfDots * 2; 
           } 

           if (start > 0 || stop < nDots - 1) { 
               CalTempContrib(start, stop); 
               for (int x = 0; x < iW; x++) { 
                   value = VerticalFilter(pbImage, startY, stopY, start, stop, 
                           x, tmpContrib); 
                   pbOut.setRGB(x, y, value); 
               } 
           } else { 
               for (int x = 0; x < iW; x++) { 
                   value = VerticalFilter(pbImage, startY, stopY, start, stop, 
                           x, normContrib); 
                   pbOut.setRGB(x, y, value); 
               } 
           } 

       } 

       return pbOut; 

   } // end of VerticalFiltering() 

   int Clip(int x) { 
       if (x < 0) 
           return 0; 
       if (x > 255) 
           return 255; 
       return x; 
   } 

   public static void main(String[] args) throws Exception{ 
        
       BufferedImage im = ImageIO.read(new File("E:\\Vista.jpg")); 
       BufferedImage image2 = new ImageScale().imageZoomOut(im,100,100); 
       ImageIO.write(image2, "JPEG", new File("e:\\6.jpg")); 
        
        
        
   } 
}