获取request里body的数据

	public String getRequestPayload(HttpServletRequest req) {  
        StringBuilder sb = new StringBuilder();  
        try(BufferedReader reader = req.getReader();) {  
                 char[]buff = new char[1024];  
                 int len;  
                 while((len = reader.read(buff)) != -1) {  
                          sb.append(buff,0, len);  
                 }  
        }catch (IOException e) {  
                 e.printStackTrace();  
        }  
        return sb.toString();  
	}

ps：contentType: "application/json", //必须有