解决Firefox OS应用中的跨域请求阻塞问题

package main

import (
    "encoding/json"
    "fmt"
    "io/ioutil"
    "net/http"

    "google.golang.org/appengine" // 假设使用App Engine
    "google.golang.org/appengine/datastore"
)

// Message 结构体用于模拟数据存储
type Message struct {
    Content string
    Date    string // 实际应用中应使用time.Time
}

func handleMessageQueue(w http.ResponseWriter, r *http.Request) {
    // 关键：设置Access-Control-Allow-Origin头，允许所有来源访问
    w.Header().Set("Access-Control-Allow-Origin", "*")

    // 处理预检请求（OPTIONS方法），CORS规范要求
    if r.Method == "OPTIONS" {
        w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS")
        w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
        w.WriteHeader(http.StatusOK)
        return
    }

    if r.Method == "POST" {
        c := appengine.NewContext(r)

        body, err := ioutil.ReadAll(r.Body)
        if err != nil {
            c.Errorf("Error reading request body: %v", err)
            http.Error(w, "Failed to read request body", http.StatusInternalServerError)
            return
        }
        defer r.Body.Close()

        // 假设body是需要存储的内容
        // auth := string(body[:]) // 原始代码中这里是auth，但实际使用是存储
        _ = string(body[:]) // 示例中简单处理，实际应解析并存储

        // 查询数据存储
        q := datastore.NewQuery("Message").Order("-Date")
        var msgs []Message
        _, err = q.GetAll(c, &msgs)

        if err != nil {
            c.Errorf("fetching msg: %v", err)
            http.Error(w, "Failed to fetch messages", http.StatusInternalServerError)
            return
        }

        w.Header().Set("Content-Type", "application/json")
        jsonMsgs, err := json.Marshal(msgs)
        if err != nil {
            c.Errorf("Error marshalling messages to JSON: %v", err)
            http.Error(w, "Failed to serialize response", http.StatusInternalServerError)
            return
        }
        fmt.Fprint(w, string(jsonMsgs))
        return
    }

    // 对于非POST请求，返回方法不允许
    http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
}

func main() {
    http.HandleFunc("/msgs", handleMessageQueue)
    // 在App Engine环境中，通常不需要显式启动监听
    // 如果是本地开发，可以添加：
    // log.Fatal(http.ListenAndServe(":8080", nil))
}

var message = "content";

// 使用 mozSystem: true 构造 XMLHttpRequest
var request = new XMLHttpRequest({mozSystem: true});
request.open('POST', 'http://localhost:8080/msgs', true);

request.onload = function () {
    if (request.status >= 200 && request.status < 400) {
        // 请求成功
        var data = JSON.parse(request.responseText);
        console.log("Success:", data);
    } else {
        // 服务器返回错误
        console.log("Server error. Status:", request.status);
    }
};

request.onerror = function () {
    // 连接错误
    console.log("Connection error occurred.");
};

request.send(message);

{
    "name": "My Firefox OS App",
    "description": "A demo Firefox OS application.",
    "launch_path": "/index.html",
    "developer": {
        "name": "Your Name",
        "url": "http://yourdomain.com"
    },
    "default_locale": "en-US",
    "permissions": {
        "systemXHR": {} // 关键：声明 systemXHR 权限
    },
    "type": "privileged" // 确保应用类型为特权
}