错误详情

• 在使用ajax向http服务器请求时，出现以下错误：

  Response to preflight request doesn't pass access control check: 
  No 'Access-Control-Allow-Origin' header is present on the requested resource.
  

• 请求如下：

  $.ajax({
      url: "http://127.0.0.1/getname",
      type: 'GET',
      success: function (data) {
          UpdateNameInput(htmlDomInputID, data);
      },
      error: function () {
          console.log("Get Rand Name Failed!");
      }
  });
  

• 服务器为golang实现

一种解决

• 查了好多资料，尝试了好多方法，最终用了这个_StackOverflow

• 即

  try {
  	var xhttp = new XMLHttpRequest();
      xhttp.open("GET", httpURL + httpGetName, false);
      xhttp.setRequestHeader("Content-type", "text/html");
      xhttp.send();
      alert(xhttp.response)
      } catch (error) {
      alert(error.message);
  }
  

  服务器

  func GetNameHandler(w http.ResponseWriter, r *http.Request) {
  	w.Header().Set("Access-Control-Allow-Origin", "*")
  	w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
  
  	randName := "NickName"
  	fmt.Fprintf(w, randName)
  }
  

• 注意
  此种方式可能并不能完全解决
  CORS: Cannot use wildcard in Access-Control-Allow-Origin when credentials flag is true
  Request header field Access-Control-Allow-Headers is not allowed by itself in preflight response

  Request header field cache-control is not allowed by Access-Control-Allow-Headers in preflight response.
  

另一种方法

• golang库-cors
• 使用
  服务器

  func StartHttpServer() bool {
  	c := cors.New(cors.Options{
  		AllowedOrigins: []string{"*"},
  	})
  
  	mux := http.NewServeMux()
  	mux.HandleFunc("/getname", GetIDHandler)
  
  	handler := c.Handler(mux)
  	http.ListenAndServe(addr, handler)
  
  	return true
  }
  

  js

  function GetRandName() {
      $.ajax({
          url: "http://127.0.0.1/getname",
          type: 'GET',
          success: function (data) {
              console.log(data)
              UpdateNameInput(htmlDomInputID, data.id);
          },
          error: function () {
              console.log("Get Rand Name Failed!");
          }
      });
  }