前端使用 axios发送数据，后端servlet无法获取的问题

问题

前端发送请求

axios({
    url:'http://localhost:8080/javaWeb/RegisController',
    method: 'POST',
    data:{
        username:user.value,
        password:truePwd.value,
        checkData:trueCode.value
    }
})

后端收到的

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException {
    //得到请求参数
    String username =req.getParameter("username");
    String password =req.getParameter("password");
    String trueCode =req.getParameter("checkData");


    System.out.println(username);//null
    System.out.println(password);//null
    System.out.println(trueCode);//null
    
    
}

请求头的问题

解决问题

后端解决

通过流来读取

  @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        StringBuilder sb = new StringBuilder();
        BufferedReader reader = req.getReader();
        char[] buf = new char[1024];
        int len;
        while ((len = reader.read(buf)) != -1){
            sb.append(buf,0,len);
        }
     System.out.println(sb.toString());
  }

前端解决

通过特定的格式来进行传递参数 不需要设置修改请求头什么等等花里胡哨的的操作

URLSearchParams：处理请求参数用的

let params = new URLSearchParams();
params.append('username', user.value);
params.append('password', truePwd.value);
params.append('checkData', trueCode.value);

axios.post('http://localhost:8080/javaWeb/RegisController', params)
    .then(response => {
    location.href="./home.html"
}, reason => {
    alert('验证码错误，请重试！');
    addData();
})

参考文档：(11条消息) vue中用axios发送请求 后端是servlet POST接收参数空_魏天的博客-CSDN博客