无法使用Volley调用POST方法

public class CustomRequest extends Request<JSONObject> {
    private Map<String, String> params;
    private Response.Listener<JSONObject> listener;

    public CustomRequest(int method, String url, Map<String, String> params,
                         Response.Listener<JSONObject> listener, Response.ErrorListener errorListener) {
        super(method, url, errorListener);
        this.params = params;
        this.listener = listener;
    }

    @Override
    protected Map<String, String> getParams() throws AuthFailureError {
        return params;
    }

    @Override
    protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
        try {
            String jsonString = new String(response.data,
                    HttpHeaderParser.parseCharset(response.headers, PROTOCOL_CHARSET));
            return Response.success(new JSONObject(jsonString),
                    HttpHeaderParser.parseCacheHeaders(response));
        } catch (UnsupportedEncodingException | JSONException e) {
            return Response.error(new ParseError(e));
        }
    }

    @Override
    protected void deliverResponse(JSONObject response) {
        listener.onResponse(response);
    }
}

String url = "https://example.com/api";
Map<String, String> params = new HashMap<>();
params.put("param1", "value1");
params.put("param2", "value2");

RequestQueue requestQueue = Volley.newRequestQueue(context);
CustomRequest request = new CustomRequest(Request.Method.POST, url, params,
        new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject response) {
                // 处理响应数据
            }
        },
        new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                // 处理错误
            }
        });

requestQueue.add(request);