Question

下载或插入JSON数据到数据库的后台或线程操作工作正常，但由于我也想更新ProgressBar，所以它以零百分比开始，并且在整个操作完成而没有任何更新时关闭。

同步片段：

String value; //defined globally

private class JsonParse extends AsyncTask<String, String, String> {

    Context mcontext;
    private ProgressDialog progressDialog;

    public JsonParse(Context context) {
        this.mcontext = context;
    }

    @Override
    protected void onCancelled() {
        super.onCancelled();
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        progressDialog = new ProgressDialog(mcontext);

        progressDialog.setTitle("Downloading"); // Setting Title
        progressDialog.setMessage("Please wait"); // Setting Message
        progressDialog.setIndeterminate(false);
        progressDialog.setMax(100);
        progressDialog.setCancelable(false);
        progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        progressDialog.setButton(DialogInterface.BUTTON_NEGATIVE, mcontext.getString(R.string.cancel_btn), new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });

        progressDialog.show();
    }

    @Override
    protected String doInBackground(String... params) {

        String choice = params[0];
        final String url = BASE_URL + "" + VERSION + "" + METHOD + "";

        StringRequest request = new StringRequest(Request.Method.POST, url,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {

                        Log.i("response", url + "response:" + response);

                        try {
                            JSONObject object = new JSONObject(response);
                            JSONArray jsonArray = object.getJSONArray(METHOD + "");

                            long counter = 0;
                            int size = jsonArray.length();

                            for (int i = 0; i <= size; i++) {

                                final JSONObject jsonObject = jsonArray.getJSONObject(i);

                                counter++;
                                int percent = (int) ((counter * 100) / size);
                                value = percent + "";

                                onProgressUpdate(value);

                                Log.i("view_", "size: " + size + " " + "counter: " + counter + " " + "percent: " + percent + "%");

                                switch (choice) {

                                    case "deaths":

                                        String id_d = jsonObject.getString("id");
                                        String family_id = jsonObject.getString("family_id");
                                        String death_one_year = jsonObject.getString("death_one_year");
                                        String no_of_deaths = jsonObject.getString("no_of_death");
                                        String cause = jsonObject.getString("cause");
                                        String cause_other = jsonObject.getString("cause_other");
                                        String ward_id_d = jsonObject.getString("ward_id");
                                        String has_error_d = jsonObject.getString("has_error");
                                        String updated_by_d = jsonObject.getString("updated_by");
                                        String updated_at_d = jsonObject.getString("updated_at");
                                        String created_at = jsonObject.getString("created_at");
                                        String uuid_d = jsonObject.getString("uuid");

                                        dbHelper.SyncDeath(Integer.parseInt(id_d), family_id, death_one_year, no_of_deaths, cause, cause_other,
                                                ward_id_d, has_error_d, updated_by_d, updated_at_d, created_at, uuid_d);

                                        death_txt.setTextColor(getResources().getColor(R.color.colorPrimary));
                                        death_txt.setText(R.string.synced);

                                        break;
                                }
                            }
                            return;

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                        progressDialog.dismiss();
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                error.printStackTrace();
                Toast.makeText(getContext(), "Server Error, Please Try Again!!", Toast.LENGTH_SHORT).show();
            }
        });

        requestQueue.add(request);

        publishProgress(value);

        Log.i("view_percent_value", value); // Getting null value

        /*for (int i = 0; i <= 100; i++){
            try {
                Thread.sleep(300);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            publishProgress(String.valueOf(i));
        }*/

        return null;
    }

    @Override
    protected void onProgressUpdate(String... values) {

        progressDialog.setProgress(Integer.parseInt(values[0]));
        value = values[0]; // Tried to update this "value" i.e. set globally but can't update

        Log.i("view_values", values[0] + "");
        super.onProgressUpdate(values);
    }

    @Override
    protected void onPostExecute(String result) {

    }
}

上面提到的代码：

 /*for (int i = 0; i <= 100; i++){
            try {
                Thread.sleep(300);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            publishProgress(String.valueOf(i));
        }*/

可以帮助我更新ProgressBar，但不能实时更新。就我而言，该参数在publishprogress（）中传递；即全局定义的“值”不会从循环中获取更新的值。我猜想，在try-catch中使用for循环可能是这种情况，但是我找不到如何将该值传递给publishprogress（）的方法；方法。

“日志”视图：

Log.i("view_", "size: " + size + " " + "counter: " + counter + " " + "percent: " + percent + "%");

正在实时更新百分比值。像这样：

请帮助我解决此问题。几个星期以来，我一直在解决这个问题。预先谢谢你！

Answer 1

第一，根据android documents，切勿手动调用onPreExecute()，onPostExecute(Result)，doInBackground(Params...)，onProgressUpdate(Progress...)。（您正在手动调用onProgressUpdate中的doInBackground）

第二，将publishProgress(value);移动到try块内的for循环。

Answer 2

尝试使用onProgressUpdate()功能设置进度。

点击此链接以供参考： android how to work with asynctasks progressdialog

在SQLite中下载和插入JSON数据时如何在android中更新Progressbar？

2 个答案: