这是我自己结合网上的一些资料封装的java图片处理类，支持图片的缩放，旋转，马赛克化。(转载请注明出处： http://blog.csdn.net/u012116457)
不多说，上代码：

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;

/**
 * 图像处理类.
 * 
 * @author nagsh
 * 
 */
public class ImageDeal {

    String openUrl; // 原始图片打开路径
    String saveUrl; // 新图保存路径
    String saveName; // 新图名称
    String suffix; // 新图类型 只支持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;
    }

    /**
     * 图片缩放.
     * 
     * @param width
     *            需要的宽度
     * @param height
     *            需要的高度
     * @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 + " 不是一个图片文件!");
        }
        BufferedImage bi = ImageIO.read(file); // 读取该图片
        // 计算x轴y轴缩放比例--如需等比例缩放，在调用之前确保参数width和height是等比例变化的
        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); // 保存图片
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    /**
     * 旋转
     * 
     * @param degree
     *            旋转角度
     * @throws Exception
     */
    public void spin(int degree) throws Exception {
        int swidth = 0; // 旋转后的宽度
        int sheight = 0; // 旋转后的高度
        int x; // 原点横坐标
        int y; // 原点纵坐标

        File file = new File(openUrl);
        if (!file.isFile()) {
            throw new Exception("ImageDeal>>>" + file + " 不是一个图片文件!");
        }
        BufferedImage bi = ImageIO.read(file); // 读取该图片
        // 处理角度--确定旋转弧度
        degree = degree % 360;
        if (degree < 0)
            degree = 360 + degree;// 将角度转换到0-360度之间
        double theta = Math.toRadians(degree);// 将角度转为弧度

        // 确定旋转后的宽和高
        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);// 确定原点坐标
        y = (sheight / 2) - (bi.getHeight() / 2);

        BufferedImage spinImage = new BufferedImage(swidth, sheight,
                bi.getType());
        // 设置图片背景颜色
        Graphics2D gs = (Graphics2D) spinImage.getGraphics();
        gs.setColor(Color.white);
        gs.fillRect(0, 0, swidth, sheight);// 以给定颜色绘制旋转后图片的背景

        AffineTransform at = new AffineTransform();
        at.rotate(theta, swidth / 2, sheight / 2);// 旋转图象
        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); // 保存图片

    }
    /**
     * 马赛克化.
     * @param size  马赛克尺寸，即每个矩形的长宽
     * @return
     * @throws Exception
     */
    public boolean mosaic(int size) throws Exception {
        File file = new File(openUrl);
        if (!file.isFile()) {
            throw new Exception("ImageDeal>>>" + file + " 不是一个图片文件!");
        }
        BufferedImage bi = ImageIO.read(file); // 读取该图片
        BufferedImage spinImage = new BufferedImage(bi.getWidth(),
                bi.getHeight(), bi.TYPE_INT_RGB);
        if (bi.getWidth() < size || bi.getHeight() < size || size <= 0) { // 马赛克格尺寸太大或太小
            return false;
        }

        int xcount = 0; // 方向绘制个数
        int ycount = 0; // y方向绘制个数
        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;   //坐标
        int y = 0;
        // 绘制马赛克(绘制矩形并填充颜色)
        Graphics gs = spinImage.getGraphics();
        for (int i = 0; i < xcount; i++) {
            for (int j = 0; j < ycount; j++) {
                //马赛克矩形格大小
                 int mwidth = size;
                 int mheight = size;
                 if(i==xcount-1){   //横向最后一个比较特殊，可能不够一个size
                     mwidth = bi.getWidth()-x;
                 }
                 if(j == ycount-1){  //同理
                     mheight =bi.getHeight()-y;
                 }
              // 矩形颜色取中心像素点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;// 计算下一个矩形的y坐标
            }
            y = 0;// 还原y坐标
            x = x + size;// 计算x坐标
        }
        gs.dispose();
        File sf = new File(saveUrl, saveName + "." + suffix);
        ImageIO.write(spinImage, suffix, sf); // 保存图片
        return true;
    }

    public static void main(String[] args) throws Exception {
        ImageDeal imageDeal = new ImageDeal("e://1.jpg", "e://", "2", "jpg");
        // 测试缩放
        /* imageDeal.zoom(200, 300); */
        // 测试旋转
        /* imageDeal.spin(90); */
        //测试马赛克
        /*imageDeal.mosaic(4);*/
    }

}