贴一个生成缩略图的类

public class ImageEncoder {
    public BufferedImage resize(BufferedImage source, int targetW,
            int targetH) {
        // 长和宽
        int type = source.getType();
        BufferedImage target = null;
        double sx = (double) targetW / source.getWidth();
        double sy = (double) targetH / source.getHeight();
        // 等比缩放
        if (sx > sy) {
            sx = sy;
            targetW = (int) (sx * source.getWidth());
        } else {
            sy = sx;
            targetH = (int) (sy * source.getHeight());
        }
        if (type == BufferedImage.TYPE_CUSTOM) {
            ColorModel cm = source.getColorModel();
            WritableRaster raster = cm.createCompatibleWritableRaster(targetW,targetH);
            boolean alphaPremultiplied = cm.isAlphaPremultiplied();
            target = new BufferedImage(cm, raster, alphaPremultiplied, null);
        } else{
            target = new BufferedImage(targetW, targetH, type);
        }
        Graphics2D g = target.createGraphics();
        // 开始画图
        g.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
        g.drawRenderedImage(source, AffineTransform.getScaleInstance(sx, sy));
        g.dispose();
        return target;
    }

    public BufferedImage getBufferedImage(String image,int width,int height){
        try {
            BufferedImage srcImage = ImageIO.read(new File(image));
            if (width > 0 || height > 0) {
                srcImage = resize(srcImage, width, height);
            }
            return srcImage;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

 

 

 

Servlet中使用实例：(/ImageProc)

 

protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        synchronized (this) {
            String img = request.getParameter("img");
            int width = Integer.parseInt(request.getParameter("width"));
            int height = Integer.parseInt(request.getParameter("height"));
            BufferedImage bi = ie.getBufferedImage(img, width, height);
            ServletOutputStream sos = response.getOutputStream();
            ImageIO.write(bi, "jpg", sos);
        }
    }

 

JSP页面使用<img/>标签指定src为这个servlet的urlparttern就可以了

 

<img src="<%=contextPath%>/ImageProc?img=D:/DEMO.jpg&width=160&height=200"/>