public static String genQRImage(String folderName, String imageName, String content) {
 //String filePath = System.getProperty("twtwebapp.root");
 String fileName = imageName + ".png";
 
 try {
 
  // 檢查是否存在imageQR目錄，不存在則先創(chuàng)建
  File file = new File(folderName);
  if (!file.exists() && !file.isDirectory()) {
  file.mkdir();
  }
  folderName = file.getAbsolutePath();
 
  int width = 200; // 圖像寬度
  int height = 200; // 圖像高度
  String format = "png";// 圖像類型
 
  Map<EncodeHintType, Object> hints = new HashMap<EncodeHintType, Object>();
  hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
  hints.put(EncodeHintType.MARGIN, 1);
  BitMatrix bitMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, width, height, hints);// 生成矩陣
  Path path = FileSystems.getDefault().getPath(folderName, fileName);
  MatrixToImageWriter.writeToPath(bitMatrix, format, path);// 輸出圖像
  log.info("二維碼已經(jīng)生成," + path);
  fileName = path.toString();
 
 } catch (Exception e) {
  log.error(e.getMessage(), e);
  fileName = null;
 }
 return fileName;
 }

@RequestMapping("qrcallback")
 public void qrcallback(HttpServletRequest request, HttpServletResponse response) throws IOException, AlipayApiException {
  
 String agent = request.getHeader("User-Agent").toLowerCase();
 System.out.println("響應頭的類型："+agent);
 if (agent.indexOf("micromessenger") > 0) {
  System.out.println("微信支付");  
 } else if (agent.indexOf("alipayclient") > 0) {
  System.out.println("阿里支付");
  
  String form = testService.aliPay();
  response.setContentType("text/html;charset=UTF-8");
  response.getWriter().write(form);//直接將完整的表單html輸出到頁面
  response.getWriter().flush();
//  response.sendRedirect("/ali.html");
 } 
 }

 <!-- alipay-sdk -->
 <dependency>
  <groupId>com.twt.charge</groupId>
  <artifactId>alipay-sdk-java</artifactId>
  <version>20160519120058</version>
 </dependency>

public String aliPay() throws AlipayApiException {
 AlipayClient alipayClient = new DefaultAlipayClient(openapi, SecurityUtil.decodeBase64(appid),
  SecurityUtil.decodeBase64(rsa_private_key), "json", "utf-8", SecurityUtil.decodeBase64(alipay_pub_key));
 AlipayTradeWapPayRequest alipayRequest = new AlipayTradeWapPayRequest();// 創(chuàng)建API對應的request
 alipayRequest.setReturnUrl("http://192.168.1.219:22222/ali.html");
 alipayRequest.setNotifyUrl("http://192.168.1.219:22222/callback");// 在公共參數(shù)中設置回跳和通知地址
 alipayRequest.setBizContent("{" + "  \"out_trade_no\":\"20160320020192222\"," + "  \"total_amount\":66.66,"
  + "  \"subject\":\"主題\"," + "  \"seller_id\":\"213215dsa\"," +
  // " \"product_code\":\"QUICK_WAP_PAY\"" +
  " }");// 填充業(yè)務參數(shù)
 String form = alipayClient.pageExecute(alipayRequest).getBody(); // 調(diào)用SDK生成表單
 
 return form;
 }

 response.setContentType("text/html;charset=UTF-8");
 response.getWriter().write(form);//直接將完整的表單html輸出到頁面
 response.getWriter().flush();