HTTP Post Request：错误400，Firebase主题消息 [英] HTTP Post Request: Error 400, Firebase Topic Messaging

问题描述

我正在尝试在Android应用程序中实现Firebase主题消息，我​​正在尝试构建HTTP post请求，并且我收到的响应代码为400.我已经查看了各种解决方案，但没有一个似乎有所帮助。

I'm trying to implement Firebase Topic Messaging in an Android application, and I'm attempting to build a HTTP post request, and I'm receiving a response code of 400. I have looked at various solutions but none of them have seemed to help.

这里是我调用AsyncTask的子类的地方：

Here is where I call the subclass of AsyncTask:

try{new FirebaseSendMessage().execute("Hello world");}
                catch (Exception e) {
                    Log.d("Exception", e.toString());
                }

这是我的Async Task类的子类。

Here is my Async Task class's subclass.

class FirebaseSendMessage  extends AsyncTask<String, Integer, Double> {
private final static String USER_AGENT = "Mozilla/5.0";
private final static String AUTH_KEY = "<My firebase authorization key obtained from firebase>";

private Exception exception;

protected Double doInBackground(String... params) {
    try {
        sendRequest(params);
    } catch (Exception e) {
        this.exception = e;
    }
    return null;
}

protected void onPostExecute(Long l) {
    // TODO: check this.exception
    // TODO: do something with the feed
}


public void sendRequest(String... params) {
    try {
        String urlString = "https://fcm.googleapis.com/fcm/send";
        URL url = new URL(urlString);
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        con.setDoOutput(true);
        con.setRequestMethod("POST");
        con.setRequestProperty("Content-Type", "application/json");
        con.setRequestProperty("Authorization", "key=" + AUTH_KEY);
        String postJsonData = "{\"to\": \"/topics/news\"\"data\": {\"message\": \"This is a Firebase Cloud Messaging Topic Message!\"}";
        con.setDoOutput(true);

        DataOutputStream wr = new DataOutputStream(con.getOutputStream());
        wr.writeBytes(postJsonData);
        wr.flush();
        wr.close();

        int responseCode = con.getResponseCode();
        System.out.println("POST Response Code :: " + responseCode);

        if (responseCode == HttpURLConnection.HTTP_OK){
            System.out.println("succeeded");
        }
        /*InputStream is = con.getInputStream();
        BufferedReader br = new BufferedReader(new InputStreamReader(is));
        String line = null;
        while ((line = br.readLine()) != null) {
            System.out.println(line);
        }
        //con.disconnect();*/
    }
    catch(IOException e){
        Log.d("exception thrown: ", e.toString());
    }
}

}

错误： I / System.out：POST响应代码:: 400

请让我知道是否需要其他代码片段来帮助我调试。提前致谢！

Please let me know if there are additional code snippets required to help me debug. Thanks in advance!

推荐答案

错误400 表示您的请求中包含无效的JSON：

Error 400 means an Invalid JSON in your request:

检查JSON消息是否格式正确并包含有效字段（例如，确保传入正确的数据类型）。

Check that the JSON message is properly formatted and contains valid fields (for instance, making sure the right data type is passed in).

在 sendRequest 中，您错过了news之间的逗号（，） \\和 \data \和结束括号（} ） ：

In your sendRequest, you missed a comma (,) between "news\" and \"data\" and a closing bracket (}):

String postJsonData = "{\"to\": \"/topics/news\"\"data\": {\"message\": \"This is a Firebase Cloud Messaging Topic Message!\"}";

如下所示：

{"to": "/topics/news/""data":{"message":"...."}

应该是：

String postJsonData = "{\"to\": \"/topics/news\", \"data\": {\"message\": \"This is a Firebase Cloud Messaging Topic Message!\"}}";

因此JSON结构是正确的：

So that the JSON structure would be correct:

{"to": "/topics/news/",
 "data":{"message":"..."}
}

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