android - 当我在 post 方法上点击 api 时得到空对象响应

Question

我有一些 json 数据，我正在尝试通过 json 获取 api 响应。但是，当我试图获得响应时，每次都会在我的 android studio logcat 上获得 W/System.err: org.json.JSONException: No value for cadet_details 这个错误。帮助我如何获得此回复。

我的活动代码：-

private void ncccadetlist(int i){

        mHandler.sendEmptyMessage(SHOW_PROG_DIALOG);
        progress_dialog_msg = "loading...";

        String Url =  "http://www.tsassessors.in/nccwork/API/cadre_sign_up_login/getApprovedCadetsListByInstitute.php";
        StringRequest stringRequest = new StringRequest(Request.Method.GET, Url,

                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String s) {

                        try {
                            JSONObject json = new JSONObject(s);
                            Log.d("status", s);
                            String status = json.getString("status");
                            String msg = json.getString("msg");


                            if (json.getString("status").equals("0")) {
                                Log.d("step1", "cadets");
                                JSONArray jsonArray = json.getJSONArray("cadet_details");


                                for (int i = 0; i < jsonArray.length(); i++) {
                                    JSONObject localJson = jsonArray.getJSONObject(i);
                                    CadetDetail cadetDetail = new CadetDetail();
                                    cadetDetail.setCadetName(localJson.getString("cadet_name"));
                                    cadetDetail.setEnrollmentNo(localJson.getString("enrollment_no"));
                                    cadetDetail.setIsIsoUploaded(localJson.getString("is_iso_uploaded"));

                                    cadetDetailsArray.add(cadetDetail);

                                    progress_dialog.dismiss();

                                }


                                /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
                            } else {
                                FancyToast.makeText(context, "" + msg , FancyToast.LENGTH_LONG, FancyToast.ERROR, false).show();
                            }

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError volleyError) {

                        FancyToast.makeText(context,"Some issue in loading",FancyToast.LENGTH_LONG,FancyToast.ERROR,false).show();
                    }
                }) {
            @Override
            protected Map<String, String> getParams() throws AuthFailureError {

                Map<String, String> params = new Hashtable<String, String>();

                Log.d("Final", "history of api");
                params.put("instt_id", insttId );
                params.put("ncc_year", "2" );




                return params;
            }
        };
        RequestQueue requestQueue = Volley.newRequestQueue(this);
        requestQueue.add(stringRequest);
    }
}

CadetDetail.java

package com.tsa.ncc_dte_punjab.models;

import java.util.HashMap;
import java.util.Map;


public class CadetDetail {


    private String cadetName;

    private String status;

    private String msg;

    private String enrollmentNo;

    private String isIsoUploaded;

    private Map<String, Object> additionalProperties = new HashMap<String, Object>();


    public String getCadetName() {
        return cadetName;
    }


    public void setCadetName(String cadetName) {
        this.cadetName = cadetName;
    }


    public String getEnrollmentNo() {
        return enrollmentNo;
    }


    public void setEnrollmentNo(String enrollmentNo) {
        this.enrollmentNo = enrollmentNo;
    }


    public String getIsIsoUploaded() {
        return isIsoUploaded;
    }


    public void setIsIsoUploaded(String isIsoUploaded) {
        this.isIsoUploaded = isIsoUploaded;
    }


    public Map<String, Object> getAdditionalProperties() {
        return this.additionalProperties;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public void setAdditionalProperty(String name, Object value) {
        this.additionalProperties.put(name, value);
    }

}

JSON响应：-

{
    "status": "1",
    "cadet_details": [
        {
            "cadet_name": "AJIT SINGH",
            "enrollment_no": "",
            "is_iso_uploaded": "0"
        },
        {
            "cadet_name": "AKASH",
            "enrollment_no": "",
            "is_iso_uploaded": "0"
        },
        {
            "cadet_name": "AKASH",
            "enrollment_no": "",
            "is_iso_uploaded": "0"
        },
        {
            "cadet_name": "AKASH ",
            "enrollment_no": "",
            "is_iso_uploaded": "0"
        },

]
}

错误：

2019-07-09 12:58:22.243 11818-11818/com.tsa.ncc_dte_punjab W/.ncc_dte_punjab: type=1400 audit(0.0:79109): avc: denied { getattr } for path="/dev/sw_sync" dev="tmpfs" ino=6638 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:sw_sync_device:s0 tclass=chr_file permissive=0
2019-07-09 12:58:22.250 11818-11818/com.tsa.ncc_dte_punjab D/status:  
    {"status":"0","msg":"Please select NCC Year"}
2019-07-09 12:58:22.250 11818-11818/com.tsa.ncc_dte_punjab D/step1: cadets
2019-07-09 12:58:22.250 11818-11818/com.tsa.ncc_dte_punjab W/System.err: org.json.JSONException: No value for cadet_details
2019-07-09 12:58:22.256 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at org.json.JSONObject.get(JSONObject.java:389)
2019-07-09 12:58:22.256 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at org.json.JSONObject.getJSONArray(JSONObject.java:584)
2019-07-09 12:58:22.256 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at com.tsa.ncc_dte_punjab.activities.AttendanceActivity$5.onResponse(AttendanceActivity.java:327)
2019-07-09 12:58:22.256 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at com.tsa.ncc_dte_punjab.activities.AttendanceActivity$5.onResponse(AttendanceActivity.java:314)
2019-07-09 12:58:22.256 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:82)
2019-07-09 12:58:22.256 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:29)
2019-07-09 12:58:22.256 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:102)
2019-07-09 12:58:22.256 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at android.os.Handler.handleCallback(Handler.java:836)
2019-07-09 12:58:22.257 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:103)
2019-07-09 12:58:22.257 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at android.os.Looper.loop(Looper.java:203)
2019-07-09 12:58:22.257 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:6251)
2019-07-09 12:58:22.257 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
2019-07-09 12:58:22.257 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
2019-07-09 12:58:22.257 11818-11818/com.tsa.ncc_dte_punjab W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)

I am trying to help by Editing , Just change the Method Of Request
 from GET to POST because GET not Passing any Parameter 
with Request so that response will be status 0

the another thing int insttId = 1; 
define some where in your code your will get success response with status 1. ```

标签： androidjsonxml

Answer 1

首先：这是一个 GET 请求，而不是您在代码中提到的 POST。

 StringRequest stringRequest = new StringRequest(Request.Method.GET, Url,

第二：对于 GET 请求，api 返回这个 json 响应

{"status":"0","msg":"Please select NCC Year"}

在此响应中不包含cadet_details对象。

您需要像这样更改代码：

try {
                        JSONObject json = new JSONObject(s);
                        Log.d("status", s);
                        String status = json.getString("status");

                        if (!status.equals("0")) {
                            Log.d("step1", "cadets");
                            JSONArray jsonArray = json.getJSONArray("cadet_details");


                            for (int i = 0; i < jsonArray.length(); i++) {
                                JSONObject localJson = jsonArray.getJSONObject(i);
                                CadetDetail cadetDetail = new CadetDetail();
                                cadetDetail.setCadetName(localJson.getString("cadet_name"));
                                cadetDetail.setEnrollmentNo(localJson.getString("enrollment_no"));
                                cadetDetail.setIsIsoUploaded(localJson.getString("is_iso_uploaded"));

                                cadetDetailsArray.add(cadetDetail);

                                progress_dialog.dismiss();

                            }


                            /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
                        } else {
                         String msg = json.getString("msg");

                            FancyToast.makeText(context, "" + msg , FancyToast.LENGTH_LONG, FancyToast.ERROR, false).show();
                        }

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }