@RequestMapping("/weixinpay/callback")
public String callBack(HttpServletRequest request){
 InputStream is = request.getInputStream();
 String xml = StreamUtil.inputStream2String(is, "UTF-8")
 /**
 * 后面把xml转成Map根据数据作逻辑处理
 */
}

/**
 * InputStream流转换成String字符串
 * @param inStream InputStream流
 * @param encoding 编码格式
 * @return String字符串
 */
public static String inputStream2String(InputStream inStream, String encoding){
 String result = null;
 try {
 if(inStream != null){
  ByteArrayOutputStream outStream = new ByteArrayOutputStream();
  byte[] tempBytes = new byte[_buffer_size];
  int count = -1;
  while((count = inStream.read(tempBytes, 0, _buffer_size)) != -1){
    outStream.write(tempBytes, 0, count);
  }
  tempBytes = null;
  outStream.flush();
  result = new String(outStream.toByteArray(), encoding);
 }
 } catch (Exception e) {
 result = null;
 }
 return result;
}