不能用asyncTask.cancel()
Cannot use asyncTask.cancel ()
我有一个 dataGetter class,我在其中加载必要的数据(url 地址、电子邮件等的一部分),然后调用 AsyncTask。
我使用抽屉菜单,其中每个片段在创建时都从新线程调用 dataGetter。如果我在片段之间快速切换(在 AsyncTask 完成之前),数据将会混合(在新片段中我将释放前一个片段中的数据)。
我试过使用 AsyncTask.cancel,但总是出错。
public class dataGetter {
@SuppressLint("StaticFieldLeak")
public static Context context;
private static String siteURL;
private static String domain;
private static boolean login;
private static String email;
private static String password;
private static AsyncRetrieve asyncRetrieve;
public static String getData(Context context, String url, String domain, boolean login, String email, String password) {
dataGetter.context = context;
dataGetter.siteURL = url;
dataGetter.domain = domain;
dataGetter.login = login;
dataGetter.email = email;
dataGetter.password = password;
String result = "";
try {
if (asyncRetrieve != null)
asyncRetrieve.cancel(true);
asyncRetrieve = new AsyncRetrieve();
result = asyncRetrieve.execute().get();
}
catch (ExecutionException | InterruptedException e) {
Sentry.capture(e);
e.printStackTrace();
}
return result;
}
public static class AsyncRetrieve extends AsyncTask<String, Void, String> {
HttpsURLConnection conn;
URL url = null;
// This method does not interact with UI, You need to pass result to onPostExecute to display
@Override
protected String doInBackground(String... params) {
.....
}
}
}
任意调用asyncRetrieve.cancel()returns出现如下错误
E/AndroidRuntime: FATAL EXCEPTION: Thread-9
Process: com.example.wedos, PID: 6709
java.util.concurrent.CancellationException
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:193)
at android.os.AsyncTask.get(AsyncTask.java:542)
at com.example.xyz.dataGetter.getData(dataGetter.java:45)
at com.example.xyz.ui.domains.DomainsFragment.getDetails(DomainsFragment.java:195)
at com.example.xyz.ui.domains.DomainsFragment.access0(DomainsFragment.java:36)
at com.example.xyz.ui.domains.DomainsFragment.run(DomainsFragment.java:74)
at java.lang.Thread.run(Thread.java:764)
我试图在互联网上搜索,但遗憾的是一无所获。
谁能告诉我如何取消 asynctask,使前一个片段的数据不出现在新片段中?
非常感谢您
编辑
第一个片段"domains"
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
//new ViewModelProvider(this).get(DomainsViewModel.class);
root = inflater.inflate(R.layout.fragment_domains, container, false);
context = root.getContext();
setHasOptionsMenu(true);
models = new ArrayList<>();
result = new ArrayList<>();
progressBar = root.findViewById(R.id.loading);
viewPager2 = root.findViewById(R.id.viewPager);
tabLayout = root.findViewById(R.id.tabs);
linearLayout = root.findViewById(R.id.DomainsLinearLayout);
thread = new Thread(new Runnable() {
@Override public void run() {
try {
getData();
} catch (JSONException e) {
Sentry.capture(e);
e.printStackTrace();
}
for (String domena : result) {
try {
getDetails(domena);
} catch (JSONException e) {
Sentry.capture(e);
e.printStackTrace();
}
}
}
});
thread.start();
check();
return root;
}
@Override
public void onDestroy() {
super.onDestroy();
asyncRetrieve.cancel(true);
System.out.println("On Destroy");
if (thread.isAlive())
thread.interrupt();
}
第二个片段"cash"
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
//new ViewModelProvider(this).get(CashViewModel.class);
View root = inflater.inflate(R.layout.fragment_cash, container, false);
context = root.getContext();
setHasOptionsMenu(true);
textView = root.findViewById(R.id.cash_amount);
progressBar = root.findViewById(R.id.loading);
linearLayout = root.findViewById(R.id.CashLinearLayout);
Button cashHistory = root.findViewById(R.id.showHistory);
cashHistory.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int index = result.indexOf(' ');
Intent i = new Intent(context, CashHistoryActivity.class);
i.putExtra("CURRENCY", result.substring(index));
startActivity(i);
}
});
thread = new Thread(new Runnable() {
@Override
public void run() {
getData();
}
});
thread.start();
return root;
}
getData() 方法
result = dataGetter.getData(context, "cashCheck", "", false, "", "");
最新错误
I/System.out: On Destroy
E/AndroidRuntime: FATAL EXCEPTION: Thread-12
Process: com.example.wedos, PID: 9115
java.util.concurrent.CancellationException
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:193)
at android.os.AsyncTask.get(AsyncTask.java:542)
at com.example.wedos.dataGetter.getData(dataGetter.java:45)
at com.example.wedos.ui.cash.CashFragment.getData(CashFragment.java:90)
at com.example.wedos.ui.cash.CashFragment.access0(CashFragment.java:25)
at com.example.wedos.ui.cash.CashFragment.run(CashFragment.java:59)
at java.lang.Thread.run(Thread.java:764)
D/io.sentry.android.event.helper.AndroidEventBuilderHelper: Proguard UUIDs file not found.
W/System.err: SLF4J: Failed to load class "org.slf4j.impl.StaticMDCBinder".
SLF4J: Defaulting to no-operation MDCAdapter implementation.
SLF4J: See http://www.slf4j.org/codes.html#no_static_mdc_binder for further details.
W/System.err: java.lang.InterruptedException
at java.util.concurrent.FutureTask.awaitDone(FutureTask.java:420)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at android.os.AsyncTask.get(AsyncTask.java:542)
at com.example.wedos.dataGetter.getData(dataGetter.java:45)
at com.example.wedos.ui.domains.DomainsFragment.getDetails(DomainsFragment.java:198)
at com.example.wedos.ui.domains.DomainsFragment.access0(DomainsFragment.java:38)
at com.example.wedos.ui.domains.DomainsFragment.run(DomainsFragment.java:76)
at java.lang.Thread.run(Thread.java:764)
I/Process: Sending signal. PID: 9115 SIG: 9
我建议删除 dataGetter
class 并删除运行 AsyncTask
的额外 Thread
。由于处理 API 响应的方式取决于片段,因此您应该创建一个 public 基础 class,例如AsyncReceiver
在单独的文件中。
public class AsyncRetrieve extends AsyncTask<String, Void, String> {
private Context context;
private Domain domain;
// etc.
public AsyncRetrieve(Context context, String domain, boolean login, String email, String password) {
this.context = context;
this.url = url;
this.domain = domain;
// etc.
}
@Override
public String doInBackground(String... params) {
return fetchData("domainList");
}
private String fetchData(String url) {
// do what you originally did in the old doInBackground
// of the old AsyncRetriever class, but use the url argument
// passed to this method
return result;
}
}
然后,在您的片段中添加实现 onPostExecute
方法的 AsyncReceiver
的私有扩展子 class。这就是您处理 API 响应并相应地更新您的视图的地方。
例如:
public class DomainsFragment extends Fragment {
private DomainsAsyncReceiver receiver;
// example text view that is updated on results
private TextView tv_results;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// instantiate your views
// e.g.
tv_results = findViewById(R.id.tv_results);
// etc.
// instantiate the async task
receiver = new DomainsAsyncReceiver(domain, url, etc.);
receiver.execute();
}
@Override
public void onDestroy() {
super.onDestroy();
// cancel the async task
receiver.cancel(true);
}
private class DomainsAsyncReceiver extends AsyncRetrieve {
@Override
protected String doInBackground(String... params) {
String result = fetchData("domainList");
// do something with the result, e.g.
String details = fetchData("domainDetails");
return details;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
tv_results.setText(result);
}
}
}
我有一个 dataGetter class,我在其中加载必要的数据(url 地址、电子邮件等的一部分),然后调用 AsyncTask。 我使用抽屉菜单,其中每个片段在创建时都从新线程调用 dataGetter。如果我在片段之间快速切换(在 AsyncTask 完成之前),数据将会混合(在新片段中我将释放前一个片段中的数据)。 我试过使用 AsyncTask.cancel,但总是出错。
public class dataGetter {
@SuppressLint("StaticFieldLeak")
public static Context context;
private static String siteURL;
private static String domain;
private static boolean login;
private static String email;
private static String password;
private static AsyncRetrieve asyncRetrieve;
public static String getData(Context context, String url, String domain, boolean login, String email, String password) {
dataGetter.context = context;
dataGetter.siteURL = url;
dataGetter.domain = domain;
dataGetter.login = login;
dataGetter.email = email;
dataGetter.password = password;
String result = "";
try {
if (asyncRetrieve != null)
asyncRetrieve.cancel(true);
asyncRetrieve = new AsyncRetrieve();
result = asyncRetrieve.execute().get();
}
catch (ExecutionException | InterruptedException e) {
Sentry.capture(e);
e.printStackTrace();
}
return result;
}
public static class AsyncRetrieve extends AsyncTask<String, Void, String> {
HttpsURLConnection conn;
URL url = null;
// This method does not interact with UI, You need to pass result to onPostExecute to display
@Override
protected String doInBackground(String... params) {
.....
}
}
}
任意调用asyncRetrieve.cancel()returns出现如下错误
E/AndroidRuntime: FATAL EXCEPTION: Thread-9
Process: com.example.wedos, PID: 6709
java.util.concurrent.CancellationException
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:193)
at android.os.AsyncTask.get(AsyncTask.java:542)
at com.example.xyz.dataGetter.getData(dataGetter.java:45)
at com.example.xyz.ui.domains.DomainsFragment.getDetails(DomainsFragment.java:195)
at com.example.xyz.ui.domains.DomainsFragment.access0(DomainsFragment.java:36)
at com.example.xyz.ui.domains.DomainsFragment.run(DomainsFragment.java:74)
at java.lang.Thread.run(Thread.java:764)
我试图在互联网上搜索,但遗憾的是一无所获。 谁能告诉我如何取消 asynctask,使前一个片段的数据不出现在新片段中?
非常感谢您
编辑
第一个片段"domains"
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
//new ViewModelProvider(this).get(DomainsViewModel.class);
root = inflater.inflate(R.layout.fragment_domains, container, false);
context = root.getContext();
setHasOptionsMenu(true);
models = new ArrayList<>();
result = new ArrayList<>();
progressBar = root.findViewById(R.id.loading);
viewPager2 = root.findViewById(R.id.viewPager);
tabLayout = root.findViewById(R.id.tabs);
linearLayout = root.findViewById(R.id.DomainsLinearLayout);
thread = new Thread(new Runnable() {
@Override public void run() {
try {
getData();
} catch (JSONException e) {
Sentry.capture(e);
e.printStackTrace();
}
for (String domena : result) {
try {
getDetails(domena);
} catch (JSONException e) {
Sentry.capture(e);
e.printStackTrace();
}
}
}
});
thread.start();
check();
return root;
}
@Override
public void onDestroy() {
super.onDestroy();
asyncRetrieve.cancel(true);
System.out.println("On Destroy");
if (thread.isAlive())
thread.interrupt();
}
第二个片段"cash"
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
//new ViewModelProvider(this).get(CashViewModel.class);
View root = inflater.inflate(R.layout.fragment_cash, container, false);
context = root.getContext();
setHasOptionsMenu(true);
textView = root.findViewById(R.id.cash_amount);
progressBar = root.findViewById(R.id.loading);
linearLayout = root.findViewById(R.id.CashLinearLayout);
Button cashHistory = root.findViewById(R.id.showHistory);
cashHistory.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int index = result.indexOf(' ');
Intent i = new Intent(context, CashHistoryActivity.class);
i.putExtra("CURRENCY", result.substring(index));
startActivity(i);
}
});
thread = new Thread(new Runnable() {
@Override
public void run() {
getData();
}
});
thread.start();
return root;
}
getData() 方法
result = dataGetter.getData(context, "cashCheck", "", false, "", "");
最新错误
I/System.out: On Destroy
E/AndroidRuntime: FATAL EXCEPTION: Thread-12
Process: com.example.wedos, PID: 9115
java.util.concurrent.CancellationException
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:193)
at android.os.AsyncTask.get(AsyncTask.java:542)
at com.example.wedos.dataGetter.getData(dataGetter.java:45)
at com.example.wedos.ui.cash.CashFragment.getData(CashFragment.java:90)
at com.example.wedos.ui.cash.CashFragment.access0(CashFragment.java:25)
at com.example.wedos.ui.cash.CashFragment.run(CashFragment.java:59)
at java.lang.Thread.run(Thread.java:764)
D/io.sentry.android.event.helper.AndroidEventBuilderHelper: Proguard UUIDs file not found.
W/System.err: SLF4J: Failed to load class "org.slf4j.impl.StaticMDCBinder".
SLF4J: Defaulting to no-operation MDCAdapter implementation.
SLF4J: See http://www.slf4j.org/codes.html#no_static_mdc_binder for further details.
W/System.err: java.lang.InterruptedException
at java.util.concurrent.FutureTask.awaitDone(FutureTask.java:420)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at android.os.AsyncTask.get(AsyncTask.java:542)
at com.example.wedos.dataGetter.getData(dataGetter.java:45)
at com.example.wedos.ui.domains.DomainsFragment.getDetails(DomainsFragment.java:198)
at com.example.wedos.ui.domains.DomainsFragment.access0(DomainsFragment.java:38)
at com.example.wedos.ui.domains.DomainsFragment.run(DomainsFragment.java:76)
at java.lang.Thread.run(Thread.java:764)
I/Process: Sending signal. PID: 9115 SIG: 9
我建议删除 dataGetter
class 并删除运行 AsyncTask
的额外 Thread
。由于处理 API 响应的方式取决于片段,因此您应该创建一个 public 基础 class,例如AsyncReceiver
在单独的文件中。
public class AsyncRetrieve extends AsyncTask<String, Void, String> {
private Context context;
private Domain domain;
// etc.
public AsyncRetrieve(Context context, String domain, boolean login, String email, String password) {
this.context = context;
this.url = url;
this.domain = domain;
// etc.
}
@Override
public String doInBackground(String... params) {
return fetchData("domainList");
}
private String fetchData(String url) {
// do what you originally did in the old doInBackground
// of the old AsyncRetriever class, but use the url argument
// passed to this method
return result;
}
}
然后,在您的片段中添加实现 onPostExecute
方法的 AsyncReceiver
的私有扩展子 class。这就是您处理 API 响应并相应地更新您的视图的地方。
例如:
public class DomainsFragment extends Fragment {
private DomainsAsyncReceiver receiver;
// example text view that is updated on results
private TextView tv_results;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// instantiate your views
// e.g.
tv_results = findViewById(R.id.tv_results);
// etc.
// instantiate the async task
receiver = new DomainsAsyncReceiver(domain, url, etc.);
receiver.execute();
}
@Override
public void onDestroy() {
super.onDestroy();
// cancel the async task
receiver.cancel(true);
}
private class DomainsAsyncReceiver extends AsyncRetrieve {
@Override
protected String doInBackground(String... params) {
String result = fetchData("domainList");
// do something with the result, e.g.
String details = fetchData("domainDetails");
return details;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
tv_results.setText(result);
}
}
}