這是我自己結合網上的一些資料封裝的java圖片處理類，支持圖片的縮放，旋轉，馬賽克化。(轉載請註明出處：http://blog.csdn.net/u012116457)
不多說，上代碼：

package deal;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import
 
 java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;

/**
 * 圖像處理類.
 * 
 * @author nagsh
 * 
 */
public class ImageDeal {

    String openUrl; // 原始圖片打開路徑
    String saveUrl; // 新圖保存路徑
    String saveName; // 新圖名稱
    String suffix; // 新圖類型 僅僅支持gif,jpg,png

    public ImageDeal(String openUrl, String saveUrl, String saveName,
            String suffix) {
        this
 
.openUrl = openUrl;
        this.saveName = saveName;
        this.saveUrl = saveUrl;
        this.suffix = suffix;
    }

    /**
     * 圖片縮放.
     * 
     * @param width
     *            須要的寬度
     * @param height
     *            須要的高度
     * @throws Exception
     */
    public void zoom(int width, int
 
 height) throws Exception {
        double sx = 0.0;
        double sy = 0.0;

        File file = new File(openUrl);
        if (!file.isFile()) {
            throw new Exception("ImageDeal>>>" + file + " 不是一個圖片文件!");
        }
        BufferedImage bi = ImageIO.read(file); // 讀取該圖片
        // 計算x軸y軸縮放比例--如需等比例縮放，在調用之前確保參數width和height是等比例變化的
        sx = (double) width / bi.getWidth();
        sy = (double) height / bi.getHeight();

        AffineTransformOp op = new AffineTransformOp(
                AffineTransform.getScaleInstance(sx, sy), null);
        File sf = new File(saveUrl, saveName + "." + suffix);
        Image zoomImage = op.filter(bi, null);
        try {
            ImageIO.write((BufferedImage) zoomImage, suffix, sf); // 保存圖片
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    /**
     * 旋轉
     * 
     * @param degree
     *            旋轉角度
     * @throws Exception
     */
    public void spin(int degree) throws Exception {
        int swidth = 0; // 旋轉後的寬度
        int sheight = 0; // 旋轉後的高度
        int x; // 原點橫坐標
        int y; // 原點縱坐標

        File file = new File(openUrl);
        if (!file.isFile()) {
            throw new Exception("ImageDeal>>>" + file + " 不是一個圖片文件!");
        }
        BufferedImage bi = ImageIO.read(file); // 讀取該圖片
        // 處理角度--確定旋轉弧度
        degree = degree % 360;
        if (degree < 0)
            degree = 360 + degree;// 將角度轉換到0-360度之間
        double theta = Math.toRadians(degree);// 將角度轉為弧度

        // 確定旋轉後的寬和高
        if (degree == 180 || degree == 0 || degree == 360) {
            swidth = bi.getWidth();
            sheight = bi.getHeight();
        } else if (degree == 90 || degree == 270) {
            sheight = bi.getWidth();
            swidth = bi.getHeight();
        } else {
            swidth = (int) (Math.sqrt(bi.getWidth() * bi.getWidth()
                    + bi.getHeight() * bi.getHeight()));
            sheight = (int) (Math.sqrt(bi.getWidth() * bi.getWidth()
                    + bi.getHeight() * bi.getHeight()));
        }

        x = (swidth / 2) - (bi.getWidth() / 2);// 確定原點坐標
        y = (sheight / 2) - (bi.getHeight() / 2);

        BufferedImage spinImage = new BufferedImage(swidth, sheight,
                bi.getType());
        // 設置圖片背景顏色
        Graphics2D gs = (Graphics2D) spinImage.getGraphics();
        gs.setColor(Color.white);
        gs.fillRect(0, 0, swidth, sheight);// 以給定顏色繪制旋轉後圖片的背景

        AffineTransform at = new AffineTransform();
        at.rotate(theta, swidth / 2, sheight / 2);// 旋轉圖象
        at.translate(x, y);
        AffineTransformOp op = new AffineTransformOp(at,
                AffineTransformOp.TYPE_BICUBIC);
        spinImage = op.filter(bi, spinImage);
        File sf = new File(saveUrl, saveName + "." + suffix);
        ImageIO.write(spinImage, suffix, sf); // 保存圖片

    }
    /**
     * 馬賽克化.
     * @param size  馬賽克尺寸，即每一個矩形的長寬
     * @return
     * @throws Exception
     */
    public boolean mosaic(int size) throws Exception {
        File file = new File(openUrl);
        if (!file.isFile()) {
            throw new Exception("ImageDeal>>>" + file + " 不是一個圖片文件!");
        }
        BufferedImage bi = ImageIO.read(file); // 讀取該圖片
        BufferedImage spinImage = new BufferedImage(bi.getWidth(),
                bi.getHeight(), bi.TYPE_INT_RGB);
        if (bi.getWidth() < size || bi.getHeight() < size || size <= 0) { // 馬賽克格尺寸太大或太小
            return false;
        }

        int xcount = 0; // 方向繪制個數
        int ycount = 0; // y方向繪制個數
        if (bi.getWidth() % size == 0) {
            xcount = bi.getWidth() / size;
        } else {
            xcount = bi.getWidth() / size + 1;
        }
        if (bi.getHeight() % size == 0) {
            ycount = bi.getHeight() / size;
        } else {
            ycount = bi.getHeight() / size + 1;
        }
        int x = 0;   //坐標
        int y = 0;
        // 繪制馬賽克(繪制矩形並填充顏色)
        Graphics gs = spinImage.getGraphics();
        for (int i = 0; i < xcount; i++) {
            for (int j = 0; j < ycount; j++) {
                //馬賽克矩形格大小
                 int mwidth = size;
                 int mheight = size;
                 if(i==xcount-1){   //橫向最後一個比較特殊。可能不夠一個size
                     mwidth = bi.getWidth()-x;
                 }
                 if(j == ycount-1){  //同理
                     mheight =bi.getHeight()-y;
                 }
              // 矩形顏色取中心像素點RGB值
                int centerX = x;
                int centerY = y;
                if (mwidth % 2 == 0) {
                    centerX += mwidth / 2;
                } else {
                    centerX += (mwidth - 1) / 2;
                }
                if (mheight % 2 == 0) {
                    centerY += mheight / 2;
                } else {
                    centerY += (mheight - 1) / 2;
                }
                Color color = new Color(bi.getRGB(centerX, centerY));
                gs.setColor(color);
                gs.fillRect(x, y, mwidth, mheight);
                y = y + size;// 計算下一個矩形的y坐標
            }
            y = 0;// 還原y坐標
            x = x + size;// 計算x坐標
        }
        gs.dispose();
        File sf = new File(saveUrl, saveName + "." + suffix);
        ImageIO.write(spinImage, suffix, sf); // 保存圖片
        return true;
    }

    public static void main(String[] args) throws Exception {
        ImageDeal imageDeal = new ImageDeal("e://1.jpg", "e://", "2", "jpg");
        // 測試縮放
        /* imageDeal.zoom(200, 300); */
        // 測試旋轉
        /* imageDeal.spin(90); */
        //測試馬賽克
        /*imageDeal.mosaic(4);*/
    }

}

java處理圖片--圖片的縮放，旋轉和馬賽克化