Android中使用Volley传递JSON请求体的实现方法指引

Hey there! Let's tackle your Volley request issues step by step.

Why Your StringRequest with getParams() Isn't Working #

First off, the getParams() method in StringRequest is built for sending form-data (x-www-form-urlencoded) parameters, but what you need is a raw JSON request body. That's why your attempts with getParams() keep failing—we need to tweak the request to send JSON instead of form data.

Fixing the StringRequest to Send JSON Body #

Here's how to modify your reqrej method to send the JSON body {"data":[{"id":"12"}]}:

// Define your target URL and JSON request body string
private static final String REQUEST_URL = "your_api_endpoint_here";
String jsonRequestBody = "{\"data\":[{\"id\":\"12\"}]}";

public void reqrej() {
    StringRequest stringRequest = new StringRequest(Request.Method.POST, REQUEST_URL,
            response -> {
                // Handle successful response
                Log.d("VolleySuccess", "Response: " + response);
            },
            error -> {
                // Handle error
                Log.e("VolleyError", "Request failed: " + error.getMessage());
            }) {
        @Override
        public byte[] getBody() throws AuthFailureError {
            // Convert your JSON string to a byte array for the request body
            try {
                return jsonRequestBody.getBytes("utf-8");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
                return super.getBody();
            }
        }

        @Override
        public Map<String, String> getHeaders() throws AuthFailureError {
            // Set the correct Content-Type header so the server recognizes JSON
            Map<String, String> headers = new HashMap<>();
            headers.put("Content-Type", "application/json; charset=utf-8");
            return headers;
        }
    };

    // Add the request to your Volley queue
    Volley.newRequestQueue(getApplicationContext()).add(stringRequest);
}

Key changes here:

• We override getBody() to return the JSON string as a UTF-8 byte array
• We set the Content-Type header to application/json in getHeaders() so the server knows how to parse the request

Using JsonObjectRequest for JSON Requests #

If you prefer a more native approach for JSON payloads, JsonObjectRequest is designed exactly for this. It handles JSON serialization and deserialization out of the box:

public void sendJsonRequest() {
    try {
        // Build your JSON request body programmatically
        JSONObject requestBody = new JSONObject();
        JSONArray dataArray = new JSONArray();
        JSONObject item = new JSONObject();
        item.put("id", "12");
        dataArray.put(item);
        requestBody.put("data", dataArray);

        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(
                Request.Method.POST,
                REQUEST_URL,
                requestBody, // Pass the JSONObject directly as the request body
                response -> {
                    // Handle successful JSON response
                    Log.d("VolleyJsonSuccess", "Response: " + response.toString());
                },
                error -> {
                    // Handle error
                    Log.e("VolleyJsonError", "Request failed: " + error.getMessage());
                }) {
            @Override
            public Map<String, String> getHeaders() throws AuthFailureError {
                // Explicitly set Content-Type (some servers require this, even though JsonObjectRequest defaults to it)
                Map<String, String> headers = new HashMap<>();
                headers.put("Content-Type", "application/json; charset=utf-8");
                return headers;
            }
        };

        // Add to Volley queue
        Volley.newRequestQueue(getApplicationContext()).add(jsonObjectRequest);
    } catch (JSONException e) {
        e.printStackTrace();
        // Handle JSON parsing errors here
    }
}

This approach avoids manually writing JSON strings, reducing the chance of syntax errors. Just build your JSONObject and JSONArray programmatically, then pass the root JSONObject to the JsonObjectRequest constructor.

内容的提问来源于stack exchange，提问作者android developer