Java实现按比例缩小图片

<div class="form-group">
    <label class="col-lg-1 col-md-1 col-sm-2 col-xs-2 label-size"><span class="c-red">*</span>头像：</label>
    <div class="col-lg-4 col-md-4 col-sm-4 col-xs-4 img-padding-zero">
        <div>
            <span id="Upload_ph" class="img-hide">
                <input type="file" title="" id="UploadFile" name="UploadFile" multiple="" class="img-input">
            </span>
            <span>
                <img alt="" src="${ctx}/UserManages/reveal_photo.do?file=tree.png">
                <a class="a-word" style="cursor:pointer;">上传图片</a>&nbsp;&nbsp;
                <a id="showApellation" class="a-word" style="font-size:12px;"></a>                
            </span>
        </div>
        <div>
            <img src="${ctx}/UserManages/reveal_photo.do?file=noImg.png" class="img-padding" width="198" height="198" alt="" id="imgOperPhoto1" onload="AutoResizeImage(198, 198, this)" title="用于头像显示">
            <img src="${ctx}/UserManages/reveal_photo.do?file=noImg_tab.png" class="img-padding" width="28" height="40" alt="" id="imgOperPhoto3" title="用于列表显示">
        </div>
    </div>
</div>

@SuppressWarnings("unused")
@RequestMapping(value="/IntOpers")
private void IntOper(@RequestParam(value="UploadFile", required=true) MultipartFile UploadFile, PrintWriter pw, HttpServletRequest request) throws IOException {
    String StrReturn = "error", FileName = "", ext = "";
    long time = 0;
    if (!UploadFile.isEmpty()) {
        if (UploadFile != null) {
            String fullName = UploadFile.getOriginalFilename();
            ext = fullName.substring(fullName.lastIndexOf("."));//获取扩展名称
            time = System.nanoTime();
            FileName = time + ext;//设置文件保存的名称
            
            //原图
            String upDir = "F:/java/upload-ssm";//文件上传路径
            FileUtils.writeByteArrayToFile(new File(upDir, FileName), UploadFile.getBytes());
            //缩小图片
            Image srcFile = ImageIO.read(new File(upDir + "/" + FileName));
            BufferedImage tag = new BufferedImage(28, 40, BufferedImage.TYPE_INT_RGB);
            tag.getGraphics().drawImage(srcFile, 0, 0, 28, 40, null);
 
            String FileName_tab = time + "_tab" + ext;//设置文件保存的名称
            FileOutputStream out = new FileOutputStream(upDir + "/" + FileName_tab);
            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
            JPEGEncodeParam jep = JPEGCodec.getDefaultJPEGEncodeParam(tag);
            
            jep.setQuality(1f, true);
            encoder.encode(tag, jep);
            out.close();
            StrReturn = "success";
        }
    }
    pw.write(StrReturn);
}