使用REST连接服务器时遇Volley 400错误，请求技术协助

Hey there! Sorry to hear you're stuck with that frustrating Volley 400 error—let's break down the most common causes and fixes to get your request working.

Common Issues & Fixes #

1. Double-Check Your Request Parameters #

A 400 error almost always means the server is rejecting your request because something's off with the data you're sending.

• Verify that phone matches the server's required format (e.g., includes country code, no special characters, correct length).
• Confirm the admin_token is valid and hasn't expired. Also, make sure the server expects the field name admin_token (sometimes it might be just token—double-check your API docs!).
• Ensure your JSONObject conversion isn't failing. Your code snippet cuts off here, so wrap the conversion in a try-catch to catch any JSONException:

  try {
      JSONObject jsonBody = new JSONObject(jsonParams);
      Log.i("log1", "Json:" + jsonBody.toString());
  } catch (JSONException e) {
      e.printStackTrace();
      Log.e("log1", "Failed to create JSON body: " + e.getMessage());
  }
  

2. Ensure Correct Content-Type Headers #

Volley's JsonObjectRequest should handle application/json by default, but sometimes misconfigurations happen. If you're using a StringRequest, you'll need to explicitly set headers:

StringRequest registerRequest = new StringRequest(Request.Method.POST, URL,
        response -> { /* Handle success response */ },
        error -> { /* Handle error */ }) {
    @Override
    public Map<String, String> getHeaders() throws AuthFailureError {
        Map<String, String> headers = new HashMap<>();
        headers.put("Content-Type", "application/json");
        return headers;
    }

    @Override
    public byte[] getBody() throws AuthFailureError {
        try {
            return new JSONObject(jsonParams).toString().getBytes("utf-8");
        } catch (Exception e) {
            Log.e("Volley", "Error creating request body", e);
            return null;
        }
    }
};
queue.add(registerRequest);

3. Validate Your URL #

The URL you shared has asterisks (http://1*4.***.**.1*1/login/register-phone)—make sure your actual URL is fully correct:

• No typos in the domain or path (e.g., is it /login/register-phone or just /register-phone?).
• Check if the server uses HTTPS instead of HTTP (some servers block unencrypted requests with a 400 error).
• Ensure the URL doesn't have any extra spaces or unintended special characters.

4. Test the API Outside Volley #

Rule out server-side issues by testing the API directly with a tool like Postman or curl:

curl -X POST http://your-real-server-url/login/register-phone \
  -H "Content-Type: application/json" \
  -d '{"phone":"your-test-phone-number", "admin_token":"your-valid-token"}'

If this also returns a 400, the problem is either with your parameters or the server setup. If it works, then the issue is in your Volley configuration.

5. Get Detailed Error Info from Volley #

Volley's error object can tell you exactly what the server is complaining about. Add this to your error listener to see the full error response:

error -> {
    if (error.networkResponse != null) {
        String errorMessage = new String(error.networkResponse.data, StandardCharsets.UTF_8);
        Log.e("VolleyError", "Status Code: " + error.networkResponse.statusCode);
        Log.e("VolleyError", "Server Error Message: " + errorMessage);
    }
}

The server's error message will often spell out the problem (e.g., "phone number is invalid" or "admin_token is missing").

内容的提问来源于stack exchange，提问作者Mohammad Derakhshan