前端html代码：

<!DOCTYPE html>
<html>
<head>  
    <meta charset="utf-8">  
    <title>控制stm32灯亮灭</title>  
</head>  

  <body > 

    <form action="http://localhost:8080/led" method="post"> 

        <input type="submit" name="on" value="开灯"> 

        <input type="submit" name="off" value="关灯"> 

    </form> 

 </body >  
</html>                                    

后端java代码：

import java.io.IOException;   //导入IO异常处理包  
    import javax.servlet.ServletException; //导入servlet异常处理包  
    import javax.servlet.http.HttpServlet; //导入HttpServlet基本包  
    import javax.servlet.http.HttpServletRequest; //导入HttpServlerRequest基本包  
    import javax.servlet.http.HttpServletResponse;//导入HttpServlerResponse基本包  
          public class Led extends HttpServlet {        
              @Override        
              protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {                  
                  String on = req .getParameter("on");                  
                  String off = req .getParameter("off");                  
                  if(null != on){                                                                                    System .out .println("开启LED");                                      }