Question

我想通过订阅从数据库获取数据的Observable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，但不同之处在于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到Observable？

MainActivity.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是实现Observer的类的实例，则可以将其强制转换为Observer

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

如果它没有实现Observer界面，那么您可以创建一个新的Observer来操纵您的导航抽屉。（您可能需要声明mDrawerLayout为最终版）

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

假设您想要从News.java类接收更新。

所以你要从你的新闻类实现Observer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(){

}

将此添加到要创建User类变量的任何类。此代码确保user1，user2对象被＆＃34;订阅＆＃34;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.

在更新任何内容时添加逻辑。 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
}

订阅导航抽屉到Observable

2 个答案: