贴一个生成缩略图的种

贴一个生成缩略图的类

1. public?class?ImageEncoder?{?????????public?BufferedImage?resize(BufferedImage?source,?int?targetW,??
2. ????????????int?targetH)?{??????????//?长和宽 ??
3. ????????int?type?=?source.getType();??????????BufferedImage?target?=?null;??
4. ????????double?sx?=?(double)?targetW?/?source.getWidth();??????????double?sy?=?(double)?targetH?/?source.getHeight();??
5. ????????//?等比缩放 ??????????if?(sx?>?sy)?{??
6. ????????????sx?=?sy;??????????????targetW?=?(int)?(sx?*?source.getWidth());??
7. ????????}?else?{??????????????sy?=?sx;??
8. ????????????targetH?=?(int)?(sy?*?source.getHeight());??????????}??
9. ????????if?(type?==?BufferedImage.TYPE_CUSTOM)?{???????????????ColorModel?cm?=?source.getColorModel();??
10. ????????????WritableRaster?raster?=?cm.createCompatibleWritableRaster(targetW,targetH);??????????????boolean?alphaPremultiplied?=?cm.isAlphaPremultiplied();??
11. ????????????target?=?new?BufferedImage(cm,?raster,?alphaPremultiplied,?null);??????????}?else{??
12. ????????????target?=?new?BufferedImage(targetW,?targetH,?type);??????????}??
13. ????????Graphics2D?g?=?target.createGraphics();??????????//?开始画图 ??
14. ????????g.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);??????????g.drawRenderedImage(source,?AffineTransform.getScaleInstance(sx,?sy));??
15. ????????g.dispose();??????????return?target;??
16. ????}???????????
17. ????public?BufferedImage?getBufferedImage(String?image,int?width,int?height){??????????try?{??
18. ????????????BufferedImage?srcImage?=?ImageIO.read(new?File(image));??????????????if?(width?>?0?||?height?>?0)?{??
19. ????????????????srcImage?=?resize(srcImage,?width,?height);??????????????}??
20. ????????????return?srcImage;??????????}?catch?(IOException?e)?{??
21. ????????????e.printStackTrace();??????????}??
22. ????????return?null;??????}??
23. }??

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Servlet中使用实例：(/ImageProc)

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1. protected?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)???????????throws?ServletException,?IOException?{??
2. ????????synchronized?(this)?{??????????????String?img?=?request.getParameter("img");??
3. ????????????int?width?=?Integer.parseInt(request.getParameter("width"));??????????????int?height?=?Integer.parseInt(request.getParameter("height"));??
4. ????????????BufferedImage?bi?=?ie.getBufferedImage(img,?width,?height);??????????????ServletOutputStream?sos?=?response.getOutputStream();??
5. ????????????ImageIO.write(bi,?"jpg",?sos);??????????}??
6. ????}??

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

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