所需的字符串参数“graphName”不存在

Question

var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function() {
      if (this.readyState == 4 && this.status == 200) {
        console.log("excel download");
      }
    };
    xhttp.open("POST", "exportGraphExcel", true);
    xhttp.setRequestHeader("Content-type", "application/msexcel");
    xhttp.send('graphName=graphakki');

It gives 400 status in browser. If Content-type is changed to "application/x-www-form-urlencoded" then request is accepted.

Answer 1

The content type in a request header is the content of what you're sending . You're not sending an Excel file, you're requesting an excel file.

When you send the "application/x-www-form-urlencoded" content type header, you're telling the server that your parameters must be read in the URL ( this is the standard way ).