rxjava mSubscription.unsubscribe onCreate是否与Activity中的onDestroy相同？
它是否将以相同的方式工作，并通过将其放在onCreate中作为subscription.subscribeOn().observeOn().subscribe().unsubscribe来取消订阅以防止内存泄漏
因为经常会调用Activity来填充下一个片段，然后弹出堆栈。如果mSubscription.unsubscribe在Activity的onDestroy中完成，则会给出RunTimeException：由于NullPointerException而无法破坏活动
我在这里错过了一些生命周期问题吗？
谢谢！
private ViewPager viewPager;
private TabLayout tabLayout;
private int mPosition;
private String id;
private Subscription mSubscription;
private Context mContext;
private RealmResults<Experience> realmResults;
private String animateExtraColumnName, tag;
private Boolean automaticUpdate, animateResults;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_employment);
User currentUser = AppDelegate.getCurrentUser();
assert currentUser != null;
mEmployee = getRealm().where(Employee.class).equalTo("user.id", currentUser.getId()).findFirst();
//Server returns Experience's ID
if (employeeExperience == null) {
AccessToken accessToken = currentUser.getAccessTokenAsTokenType(AppDelegate.getContext(), "Bearer");
employeeExperienceAPIOAuth2Call apiCall = new employeeExperienceAPIOAuth2Call(AppDelegate.getContext(), accessToken);
Observable<ResponseEmployeeExperience> postEmployeeExperienceObservable = apiCall.postEmployeeExperiencesRX();
mSubscription = postEmployeeExperienceObservable
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe((data) -> {
Log.d(TAG, "onCreate: Subscribe ");
employeeExperience = data.getEmployeeExperience();
Log.d(TAG, "onCreate: employeeExperience.getId()");
getRealm().beginTransaction();
getRealm().copyToRealmOrUpdate(employeeExperience);
// This adds the new employeeExperience object into the EmployeeExperiences RealmList
employee.employeeExperiences.add(employeeExperience);
getRealm().commitTransaction();
getRealm().close();
//unsubscribe here because the activity doesnt close itself to begin with?
mSubscription.unsubscribe();
Log.d(TAG, "onCreate: Unsubscribe: ");
// prepare data needed by our fragment
FragmentAddOrUpdateEmploymentHistory addEmploymentHistoryFragment = new FragmentAddOrUpdateEmploymentHistory();
FragmentManager fm = getSupportFragmentManager();
fm.beginTransaction().replace(R.id.edit_frame_layout, addEmploymentHistoryFragment, "EDIT_FRAGMENT").commit();
}, (error) -> {
// TODO do whatever error handling we need to do here
Log.d(TAG, "onCreate: postEmployeeExp error");
error.printStackTrace();
});
}
} else if (employee.getEmployeeExperiences() != null) {
employeeExperience = getRealm().where(employeeExperience.class).equalTo("id", id).findFirst();
FragmentAddOrUpdateEmploymentHistory addEmploymentHistoryFragment = new FragmentAddOrUpdateEmploymentHistory();
FragmentManager fm = getSupportFragmentManager();
fm.beginTransaction().replace(R.id.edit_frame_layout, addEmploymentHistoryFragment, "EDIT_FRAGMENT").commit();
}
ImageButton checkButton = (ImageButton) findViewById(R.id.edit_toolbar_check);
checkButton.setOnClickListener(this);
ImageButton crossButton = (ImageButton) findViewById(R.id.edit_toolbar_cross);
crossButton.setOnClickListener(this);
}
@Override
protected void onStart() {
super.onStart();
}
@Override
public void onClick(View view) {
Fragment editFragments = getSupportFragmentManager().findFragmentByTag("EDIT_FRAGMENT");
switch (view.getId()) {
case R.id.edit_toolbar_check:
if (editFragments instanceof FragmentEditDate) {
Log.d(TAG, "onClick: editdate ");
getSupportFragmentManager().popBackStack();
} else if (editFragments instanceof FragmentSalary){
Log.d(TAG, "onClick: salary ");
getSupportFragmentManager().popBackStack();
} else if (editFragments instanceof FragmentAddOrUpdateEmploymentHistory) {
Log.d(TAG, "onClick: employmenthistory ");
finish();
} else if (editFragments instanceof FragmentSingleChoice) {
Log.d(TAG, "singlechoice " );
getSupportFragmentManager().popBackStack();
}
else if (editFragments instanceof FragmentMultipleChoice) {
Log.d(TAG, "multiplechoice " );
getSupportFragmentManager().popBackStack();
}
break;
case R.id.edit_toolbar_cross:
if (editFragments instanceof FragmentAddOrUpdateEmploymentHistory) {
getRealm().beginTransaction();
employeeExperience.DELETE();
getRealm().commitTransaction();
getRealm().close();
}
finish();
} else {
finish();
}
} else {
getSupportFragmentManager().popBackStack(); }
break;
}
}
最佳答案
简而言之-订阅Observable后，您就可以接收来自它的通知并对其作出反应（onNext，onError，onComplete）。同样，在大多数情况下（对于冷的可观察物），这实际上是Observable开始发射物品的触发点。
来自Observable的Unsubscribing表示您不再有兴趣接收任何进一步的通知。当您不再想要接收任何东西时，您需要unsubscribe，这与在Activity的onDestroy()方法中释放任何资源的方式类似。当然，与活动的生命周期相似只是为了进行比较-订阅/取消订阅过程是完全独立的。
您可以阅读有关subscribing和unsubscribing含义的详细信息[HERE] [1] [1]：http://reactivex.io/documentation/contract.html
也就是说，对您的代码的一些具体建议：
您目前在Android的主线程上执行了太多操作。我建议将所有与实物相关的内容作为RX链的一部分，而不是在onNext()中的subscribe(...)处理程序中移动。这样，它将在io线程上执行。就像是：
...
mSubscription = postEmployeeExperienceObservable
.subscribeOn(Schedulers.io())
.doOnNext(data -> saveDataToRealm(data))
.observeOn(AndroidSchedulers.mainThread())
.subscribe((data) -> {
// prepare data needed by our fragment
FragmentAddOrUpdateEmploymentHistory addEmploymentHistoryFragment = new FragmentAddOrUpdateEmploymentHistory();
FragmentManager fm = getSupportFragmentManager();
fm.beginTransaction().replace(R.id.edit_frame_layout, addEmploymentHistoryFragment, "EDIT_FRAGMENT").commit();
}, (error) -> {
// TODO do whatever error handling we need to do here
Log.d(TAG, "onCreate: postEmployeeExp error");
error.printStackTrace();
});
}
private Data saveDataToRealm(Data data) {
employeeExperience = data.getEmployeeExperience();
Log.d(TAG, "onCreate: employeeExperience.getId()");
getRealm().beginTransaction();
getRealm().copyToRealmOrUpdate(employeeExperience);
// This adds the new employeeExperience object into the EmployeeExperiences RealmList
employee.employeeExperiences.add(employeeExperience);
getRealm().commitTransaction();
getRealm().close();
}
就取消订阅而言-如果您真的想从
unsubscribe事件中进行onNext()预订，一种更好的策略是通过Subscriber<Data>进行订阅，然后使用它的unsubscribe()方法。换句话说-您不会呼叫mSubscription.unsubscribe()，而是呼叫this.unsubscribe()。mSubscription = postEmployeeExperienceObservable
.subscribeOn(Schedulers.io())
.doOnNext(data -> saveDataToRealm(data))
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber<Data>() {
@Override
public void onCompleted() {
}
@Override
public void onError(Throwable e) {
}
@Override
public void onNext(Data data) {
...
this.unsubscribe();
}
});
综上所述，我认为您并不是真的需要使用
unsubscribe方法中的onNext()，而是可以在onDestroy()中这样做，当然可以检查先前是否创建了预订：@Override
protected void onDestroy() {
super.onDestroy();
if (mSubscription != null) {
mSubscription.unsubscribe();
}
}