Cha*_* Li 11 android android-progressbar android-asynctask
我有一个GoogleTranslate.java文件,其中包含一个扩展AsyncTask的类GoogleTranslate.此任务的目的是执行Google翻译.
我有另一个类MyVocab,它允许用户在警告对话框中输入要翻译的单词.因此,只需单击警告对话框按钮,即可通过调用GoogleTranslate类将该单词翻译为所需语言.但是,当我将进度条从MyVocab传递到GoogleTranslate时,它不起作用.当操作正在运行时(可观察的时间量),进度条不会显示.我在onPreExecute中将进度条设置为VISIBLE,并在onPostExecute中将其设置为GONE.
我想知道是不是因为我在两个不同的java文件中有GoogleTranslate和MyVocab,因为我看到的大多数示例都有异步类和在同一个java文件中调用它的类.请告诉我,如果有什么我做错了导致这个问题.
这是相关的代码:
GoogleTranslate.java
public class GoogleTranslate extends AsyncTask<String, Void, String>{
private ProgressBar mProgressBar;
public GoogleTranslate(ProgressBar progressBar) {
super();
mProgressBar = progressBar;
}
@Override
protected void onPreExecute() {
mProgressBar.setVisibility(View.VISIBLE);
}
@Override
protected void onPostExecute(String s) {
mProgressBar.setVisibility(View.GONE);
}
@Override
protected String doInBackground(String... params) {
String vocab = params[0];
String source = params[1];
String target = params[2];
String sourceQuery = "";
String targetQuery = "&target=" + target;
// "" means its
if (!source.equals("Detect Language")) {
sourceQuery = "&source=" + source;
}
try {
String APIKey = "MY_API_KEY";
String encodedQuery = URLEncoder.encode(vocab, "UTF-8");
URL url = new URL("https://www.googleapis.com/language/translate/v2?key=" +
APIKey +
"&q=" +
encodedQuery +
sourceQuery +
targetQuery);
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder stringBuilder = new StringBuilder();
String line;
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line).append("\n");
}
bufferedReader.close();
return stringBuilder.toString();
}
finally {
urlConnection.disconnect();
}
}
catch (Exception e) {
return null;
}
}
}
MyVocab的方法部分:
protected void addVocabAlertDialog(final VocabDbHelper dbHelper, final String category,
final VocabCursorAdapter cursorAdapter) {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Add Vocab");
LayoutInflater li = LayoutInflater.from(CategoryItem.this);
View promptsView = li.inflate(R.layout.alert_dialog_add_vocab, null);
final EditText vocabInput = (EditText) promptsView.findViewById(R.id.vocabInput);
final EditText definitionInput = (EditText) promptsView.findViewById(R.id.definitionInput);
final ProgressBar progressBar = (ProgressBar) promptsView.findViewById(R.id.progressBar);
builder.setView(promptsView);
final GoogleTranslate googleTranslate = new GoogleTranslate(progressBar);
// Set up the buttons
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
String vocab = vocabInput.getText().toString();
String definition = definitionInput.getText().toString();
dbHelper.insertVocab(category, vocab, definition, 0);
if (!category.equals(VocabDbContract.CATEGORY_NAME_MY_WORD_BANK)) {
dbHelper.insertVocab(VocabDbContract.CATEGORY_NAME_MY_WORD_BANK, vocab, definition, 0);
}
// Update Cursor
Cursor cursor = dbHelper.getVocabCursor(category);
cursorAdapter.changeCursor(cursor);
}
});
final AlertDialog dialog = builder.create();
dialog.show();
dialog.getButton(AlertDialog.BUTTON_NEUTRAL).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String vocab = vocabInput.getText().toString();
SharedPreferences sharedPreferences = getSharedPreferences("Translation", MODE_PRIVATE);
int sourcePos = sharedPreferences.getInt("Source", 0); // 0 is for Detect Language
int targetPos = sharedPreferences.getInt("Target", 19); // 19 is for English
String source = LanguageOptions.FROM_LANGUAGE_CODE[sourcePos];
String target = LanguageOptions.TO_LANGUAGE_CODE[targetPos];
final AlertDialog.Builder builder = new AlertDialog.Builder(CategoryItem.this);
builder.setMessage("Network is unavailable. Please try again later.");
builder.setNegativeButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
AlertDialog dialog = builder.create();
if (isNetworkAvailable()) {
AsyncTask<String, Void, String> asyncTask = googleTranslate.execute(vocab, source, target);
try {
String translatedJSON = asyncTask.get();
JSONParser jsonParser = new JSONParser();
String translatedText = jsonParser.parseJSONForTranslation(translatedJSON);
definitionInput.setText(translatedText);
} catch (Exception e) {
dialog.show();
}
}
else {
dialog.show();
}
}
});
}
包含进度条的XML文件:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Vocab"
android:id="@+id/vocabInput"
android:inputType="textAutoComplete"/>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Definition"
android:id="@+id/definitionInput"
android:inputType="textAutoComplete"
android:layout_below="@+id/vocabInput"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:visibility="gone"
android:indeterminate="true"
android:id="@+id/progressBar"/>
我建议ProgressDialog改用.
我切换,ProgressBar因为我遇到了类似的问题,即使在我的默认构造函数中以编程方式创建一个AsyncTask.
public class GoogleTranslate extends AsyncTask<String, Void, String> {
private ProgressDialog mProgressDialog;
private Context mContext;
public GoogleTranslate(Context context) {
mContext = context;
}
@Override
protected void onPreExecute() {
mProgressDialog = ProgressDialog.show(
mContext,
"Please wait", // Title
"Translating", // Message
true // Indeteriminate flag
);
}
@Override
protected String doInBackground(String... params) {
...
}
@Override
protected void onPostExecute(String s) {
if (mProgressDialog != null) {
mProgressDialog.dismiss();
}
...
}
}
这样称呼AsyncTask:
new GoogleTranslate(getActivity() /* or getContext() */).execute(vocab, source, target);
尽量避免使用 AsyncTask get() 方法并使用侦听器。您应该这样更新您的代码：
1) 在你的 googleTranslate 类中，添加一个监听器：
private Listener listener;
public interface Listener{
void onTaskResult(String string);
}
public void setListener(Listener listener){
this.listener = listener;
}
并在 onPostExecute 中调用它：
@Override
protected void onPostExecute(String s) {
if (listener!=null){ listener.onTaskResult(s); }
mProgressBar.setVisibility(View.GONE);
}
2）更新您的主类，用侦听器管理替换 get ，替换：
AsyncTask<String, Void, String> asyncTask = googleTranslate.execute(vocab, source, target);
try {
String translatedJSON = asyncTask.get();
JSONParser jsonParser = new JSONParser();
String translatedText = jsonParser.parseJSONForTranslation(translatedJSON);
definitionInput.setText(translatedText);
} catch (Exception e) {
dialog.show();
}
有了这个：
googleTranslate.setListener(new GoogleTranslate.Listener() {
@Override
public void onTaskResult(String string) {
String translatedJSON = string;
JSONParser jsonParser = new JSONParser();
String translatedText = jsonParser.parseJSONForTranslation(translatedJSON);
definitionInput.setText(translatedText);
}
});
googleTranslate.execute(vocab, source, target);
我希望它有帮助。