将导航抽屉订阅到可观察量

Question

我想通过订阅从数据库获取数据的Observable来填充导航抽屉，完成后通知订阅者(使用 RxJava(。我已经做了类似的事情，Subscriber是一个扩展Fragment的类，但不同的是，导航抽屉不是一个单独的片段，而是在 MainActivity 中定义的。

如何订阅Navigation Drawer Observable？

主要活动.java

private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
@Override
public void onStart() {                                                                                                                       mLoadAndStoreDataObservable = Observable.create(
    super.onStart();                                                                                                                              new Observable.OnSubscribe<String>() {
    // fragment creation code was here
    // populates a String[] myStringArray for Navigation Drawer                                                                                                                                                                  permitsSQLiteManager.addLogLine(mActivity, logString);
    if (!skipRestfulServiceCall) {
        getDataFromRestfulService();                                                                                                                      }
    }                                                                                                                                                     catch (Exception e) {
    else {  // get data from SQLite                                                                                                                           Log.e("loadAndStoreData  ", "Exception: " + e.getMessage());
        getDataFromSQLite();                                                                                                                                  mProgressDialog.dismiss();
    }                                                                                                                                                     }
                                                                                                                                                      }
    mTitle = mDrawerTitle = getTitle();                                                                                                           }
    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);                                                                              .subscribeOn(Schedulers.io())
    mDrawerList = (ListView) findViewById(R.id.left_drawer);                                                                                      .observeOn(AndroidSchedulers.mainThread())
                                                                                                                                                  .subscribe(mDrawerLayout); // parameter was a Fragment
    mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
    mDrawerList.setAdapter(new ArrayAdapter<String>(this,  R.layout.drawer_list_item, myStringArray));
    mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
    // enable ActionBar app icon to behave as action to toggle nav drawer
    getActionBar().setDisplayHomeAsUpEnabled(true);
    getActionBar().setHomeButtonEnabled(true);
    mDrawerToggle = new ActionBarDrawerToggle(this,mDrawerLayout, R.drawable.ic_drawer, R.string.drawer_open,R.string.drawer_close
    ) {
        public void onDrawerClosed(View view) {
            getActionBar().setTitle(mTitle);
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }
        public void onDrawerOpened(View drawerView) {
            getActionBar().setTitle(mDrawerTitle);
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }
    };
    mDrawerLayout.setDrawerListener(mDrawerToggle);
}
private void getDataFromRestfulService() {
    <get data>

    // implement RxJava-Observable/Subscriber
    mLoadAndStoreDataObservable = Observable.create(
            new Observable.OnSubscribe<String>() {
                @Override
                public void call(Subscriber<? super String> subscriber) {
                    try {
                        Utilities.loadAndStoreData(mActivity);
                        subscriber.onNext("Utilities.loadAndStoreData Done");
                        //subscriber.onCompleted();
                        Log.e("MainActivity.onCreate()", "subscriber.onNext("Utilities.loadAndStoreData Done")");
                        String logString = "MainActivity.onCreate() - subscriber.onNext(Utilities.loadAndStoreData Done)";
                        Log.e(TAG, logString);
                        PermitsSQLiteManager permitsSQLiteManager = PermitsSQLiteManager.getInstance();
                        permitsSQLiteManager.addLogLine(mActivity, logString);
                        mProgressDialog.dismiss();
                    }
                    catch (Exception e) {
                        Log.e("loadAndStoreData  ", "Exception: " + e.getMessage());
                        subscriber.onError(e);
                        mProgressDialog.dismiss();
                    }
                }
            }
    )
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())
    .subscribe(mDrawerLayout); // compile error // suscriber was a Fragment, but no longer
}

Answer 1

如果mDrawerLayout是一个实现Observer的类的实例，那么你可以把它投射到Observer

NavigationDrawer mDrawerLayout = ...
yourObservable.subscribe((Observer)mDrawerLayout);

如果它没有实现Observer接口，则可以创建一个将操作导航抽屉的新Observer。(您可能需要声明mDrawerLayout为最终决定(

final NavigationDrawer  mDrawerLayout = ...
yourObservable.subscribe(new Observer<String>() {
                @Override
                public void onCompleted() {
                    // on completed
                }
                @Override
                public void onError(Throwable throwable) {
                    // on error
                }
                @Override
                public void onNext(String people) {
                        mDrawerLayout.doSomething(); 
                }
            });

Answer 2

假设您要接收来自 News.java 类的更新。

因此，您可以从新闻类实现观察器接口

News implements Observable{
   public void publishNews(){
       String newNews = "newNews";
       //Now notify Users that new news is available by calling the following
       // two methods
       setChanged();
       notifyObservers(); // This will call the subscribers and notify them 
                          // that there is a change.
   }
}

现在，您希望用户接收更新。

public class User implements Observer(){
}

将其添加到要创建用户类变量的任何类中。此代码确保用户 1、用户 2 对象"订阅"到新闻类

News news = new News();
User user1 = new User();
User user2 = new User();
news.add(user1); // You have to instantiate News object to user the add method
news.add(user2); // from Observable interface.

update(( 方法由 Observer 提供接口。

@Overrride
public void update(Observable, Object){
// This gets called after notifyObservers() in the Observable class
// Whatever you want to do after Observable calls notifyObservers, goes here
}