问跨域请求被阻止

EN

func handleMessageQueue(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Access-Control-Allow-Origin", "*")
    if r.Method == "POST" {

        c := appengine.NewContext(r)

        body, _ := ioutil.ReadAll(r.Body)

        auth := string(body[:])
        r.Body.Close()
        q := datastore.NewQuery("Message").Order("-Date")

        var msg []Message
        key, err := q.GetAll(c, &msg)

        if err != nil {
            c.Errorf("fetching msg: %v", err)
            return
        }

        w.Header().Set("Content-Type", "application/json")
        jsonMsg, err := json.Marshal(msg)
        msgstr := string(jsonMsg)
        fmt.Fprint(w, msgstr)
        return
    }
}

var message = "content";

request = new XMLHttpRequest();
request.open('POST', 'http://localhost:8080/msgs', true);

request.onload = function () {
    if (request.status >= 200 && request.status < 400) {
        // Success!
        data = JSON.parse(request.responseText);
        console.log(data);
    } else {
        // We reached our target server, but it returned an error
        console.log("server error");
    }
};

request.onerror = function () {
    // There was a connection error of some sort
    console.log("connection error");
};

request.send(message);

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://localhost:8080/msgs. This can be fixed by moving the resource to the same domain or enabling CORS.