我一直在使用AsyncTask下载某个文件，并完成了一些教程，但未能获得进度条以随下载进行移动。代码是AsyncTask，它调用一个方法进行HTTP连接，然后返回以正确的方式对数据进行分类以为应用程序处理数据
这是我在MainActivity上的AsynTask
private class getFood extends AsyncTask<Void, Integer, Cursor> {
private ProgressDialog mProgressDialog;
@Override
protected Cursor doInBackground(Void... params) {
// Create URL object
String site = "https://afternoon-ridge-50060.herokuapp.com/allsnacks";
URL url = createUrl(site);
// Perform HTTP request to the URL and receive a JSON response back
String jsonResponse = null;
try {
String jsonResponseEmpty = "";
// If the URL is null, then return early.
if (url == null) {
jsonResponse = jsonResponseEmpty;
}
HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
assert url != null;
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setReadTimeout(20000 /* milliseconds */);
urlConnection.setConnectTimeout(25000 /* milliseconds */);
urlConnection.setRequestMethod("GET");
urlConnection.setRequestProperty("Authorization", "\"token\": " + token);
urlConnection.connect();
// If the request was successful (response code 200),
// then read the input stream and parse the response.
if (urlConnection.getResponseCode() == 200) {
int fileLength = urlConnection.getContentLength();
Log.d("size", String.valueOf(fileLength));
inputStream = urlConnection.getInputStream();
StringBuilder output = new StringBuilder();
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
jsonResponse = output.toString();
} else {
Log.e(LOG_TAG, "Error response code: " + urlConnection.getResponseCode());
}
} catch (IOException e) {
Log.e(LOG_TAG, "Problem retrieving the Food JSON results.", e);
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (inputStream != null) {
// Closing the input stream could throw an IOException, which is why
// the makeHttpRequest(URL url) method signature specifies than an IOException
// could be thrown.
inputStream.close();
}
}
} catch (IOException e) {
Log.e(LOG_TAG, "Problem making the HTTP request.", e);
}
// Extract relevant fields from the JSON response and create a list of {@link Earthquake}s
//*List<FoodList> Food = extractFeatureFromJson(jsonResponse);
Cursor foodTable = extractFeatureFromJson(jsonResponse);
// Return the list of {@link Earthquake}s
Log.d("food", "done");
return foodTable;
}
@Override
protected void onProgressUpdate(Integer... values) {
// if we get here, length is known, now set indeterminate to false
mProgressDialog.setProgress(values[0]);
}
@Override
protected void onPreExecute() {
super.onPreExecute();
// Create progress dialog
mProgressDialog = new ProgressDialog(loginActivity.this);
// Set your progress dialog Title
mProgressDialog.setTitle("Downloading");
// Set your progress dialog Message
mProgressDialog.setMessage("Downloading Important Files, Please Wait!");
mProgressDialog.setIndeterminate(false);
mProgressDialog.setMax(100);
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
// Show progress dialog
mProgressDialog.show();
}
@Override
protected void onPostExecute(Cursor data) {
try {
int foodNumberColIndex = data.getColumnIndex(COLUMN_NDB_NO);
int foodNameColIndex = data.getColumnIndex(COLUMN_NAME);
int waterColIndex = data.getColumnIndex(COLUMN_WATER_G);
int energyColIndex = data.getColumnIndex(COLUMN_ENERGY_KCAL);
int proteinColIndex = data.getColumnIndex(COLUMN_PROTEIN_G);
int lipidColIndex = data.getColumnIndex(COLUMN_LIPID_TOT_G);
int ashColIndex = data.getColumnIndex(COLUMN_ASH_G);
int carboColIndex = data.getColumnIndex(COLUMN_CARBOHYDRT_G);
while (data.moveToNext()) {
Log.d("in", " progress");
FoodList foodItem = new FoodList(data.getInt(foodNumberColIndex),
data.getString(foodNameColIndex).trim().replace(",", "."),
data.getDouble(waterColIndex),
data.getDouble(energyColIndex),
data.getDouble(proteinColIndex),
data.getDouble(lipidColIndex),
data.getDouble(ashColIndex),
data.getDouble(carboColIndex));
allFood.add(foodItem);
}
} finally {
data.close();
}
mProgressDialog.dismiss();
startActivity(intentNew);
}
private URL createUrl(String stringUrl) {
URL url = null;
try {
url = new URL(stringUrl);
} catch (MalformedURLException e) {
Log.e(LOG_TAG, "Problem building the URL ", e);
}
return url;
}
private Cursor extractFeatureFromJson(String foodJSON) {
// If the JSON string is empty or null, then return early.
if (TextUtils.isEmpty(foodJSON)) {
return null;
}
try {
// Create a JSONArray from the JSON response string
JSONArray foodArray = new JSONArray(foodJSON);
for (int i = 0; i < foodArray.length(); i++) {
JSONObject foodObject = foodArray.getJSONObject(i);
ContentValues values = new ContentValues();
values.put(COLUMN_NDB_NO, foodObject.optInt(COLUMN_NDB_NO));
values.put(COLUMN_NAME, foodObject.optString(COLUMN_NAME));
values.put(COLUMN_WATER_G, foodObject.optDouble(COLUMN_WATER_G));
values.put(COLUMN_ENERGY_KCAL, foodObject.optDouble(COLUMN_ENERGY_KCAL));
values.put(COLUMN_PROTEIN_G, foodObject.optDouble(COLUMN_PROTEIN_G));
values.put(COLUMN_LIPID_TOT_G, foodObject.optDouble(COLUMN_LIPID_TOT_G));
values.put(COLUMN_ASH_G, foodObject.optDouble(COLUMN_ASH_G));
values.put(COLUMN_CARBOHYDRT_G, foodObject.optDouble(COLUMN_CARBOHYDRT_G));
foodNutriProvider insert = new foodNutriProvider();
insert.insert(CONTENT_URI, values);
}
} catch (JSONException e) {
// If an error is thrown when executing any of the above statements in the "try" block,
// catch the exception here, so the app doesn't crash. Print a log message
// with the message from the exception.
Log.e("foodSearch", "Problem parsing the earthquake JSON results", e);
Log.e("foodSearch", foodJSON);
}
foodNutriProvider getTable = new foodNutriProvider();
// Return the list of earthquakes
return getTable.query(CONTENT_URI, null, null, null, null);
}
}
答案 0 :(得分：0)
您必须发布进度，然后只有Integer... values具有适当的值。
类似的东西：
@Override
protected String doInBackground(Context... params) {
//Part-1 of the task done
publishProgress(20);
//Part-2 of the task done
publishProgress(50);
//Part-3 of the task done
publishProgress(100);
return “success”;
}
答案 1 :(得分：0)
根据android文档：
“ onProgressUpdate（Progress ...），在调用publishProgress（Progress ...）之后在UI线程上调用。执行的时间未定义。此方法用于在用户中显示任何形式的进度界面，而后台计算仍在执行。例如，它可用于为进度栏设置动画或在文本字段中显示日志。
使用它