RxJava的入门和基本使用

导包

在module的gradle中:    compile "io.reactivex.rxjava2:rxjava:2.0.1"    compile "io.reactivex.rxjava2:rxandroid:2.0.1"

基本概念

        //使用Observable.create()方法构造一个被观察对象        Observable<Integer> objectObservable = Observable.create(new ObservableOnSubscribe<Integer>() {            @Override            public void subscribe(ObservableEmitter<Integer> e) throws Exception {                //e.onNext(T)发起事件                e.onNext(1);                e.onNext(2);                e.onNext(3);                //结束事件                e.onComplete();            }        });        //观察者对象,在被观察者发起事件时接收事件        Observer observer=new Observer<Integer>(){            //在订阅时调用            @Override            public void onSubscribe(Disposable d) {                Log.v("meee",getClass()+":\n"+"onSubscribe");            }            //在接收事件时调用            @Override            public void onNext(Integer value) {                Log.v("meee",getClass()+":\n"+"onNext"+value);            }            //在出现错误时调用            @Override            public void onError(Throwable e) {                Log.v("meee",getClass()+":\n"+"onError");            }            //在事件结束时调用            @Override            public void onComplete() {                Log.v("meee",getClass()+":\n"+"onComplete");            }        };        //绑定观察者和被观察者        objectObservable.subscribe(observer);

运行结果:09-29 17:26:07.939 28098-28098/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$2:                                                       onSubscribe09-29 17:26:07.939 28098-28098/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$2:                                                       onNext109-29 17:26:07.939 28098-28098/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$2:                                                       onNext209-29 17:26:07.939 28098-28098/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$2:                                                       onNext309-29 17:26:07.939 28098-28098/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$2:                                                       onComplete

ObservableEmitter:事件的发起者,通过调用emitter的onNext(T value)、onComplete()和onError(Throwable error)就可以分别发出next事件、complete事件和error事件。1.可以发送无限个onNext, 观察者可以接收无限个onNext.2.发送了一个onComplete后, 事件将会继续发送, 但观察者收到onComplete事件之后将不再继续接收事件.3.发送了一个onError后, 事件将会继续发送, 但观察者收到onComplete事件之后将不再继续接收事件.4.可以不发送onComplete或onError.5.onComplete和onError必须唯一并且互斥, 即不能发多个onComplete, 也不能发多个onError, 也不能先发一个onComplete, 然后再发一个onError, 反之亦然6.发送多个onComplete,在接收到第一个onComplete后不再接收;但发送多个error会崩溃

切断联系

Disposable,废弃dispose()方法时, 观察者不能在接收事件,但被观察者会继续发送事件

        Observable<Integer> objectObservable = Observable.create(new ObservableOnSubscribe<Integer>() {            @Override            public void subscribe(ObservableEmitter<Integer> e) throws Exception {                Log.v("meee",getClass()+":\n"+"emit1");                e.onNext(1);                Log.v("meee",getClass()+":\n"+"emit2");                e.onNext(2);                Log.v("meee",getClass()+":\n"+"emit3");                e.onNext(3);                e.onComplete();            }        });        Observer observer=new Observer<Integer>(){        //将Disposable 作为成员变量            Disposable mDisposable;            @Override            public void onSubscribe(Disposable d) {                mDisposable=d;                Log.v("meee",getClass()+":\n"+"onSubscribe");            }            @Override            public void onNext(Integer value) {                if (value==2){                    //切断观察者和被观察者间的联系                    mDisposable.dispose();                }                Log.v("meee",getClass()+":\n"+"onNext"+value);            }            @Override            public void onError(Throwable e) {                Log.v("meee",getClass()+":\n"+"onError");            }            @Override            public void onComplete() {                Log.v("meee",getClass()+":\n"+"onComplete");            }        };        objectObservable.subscribe(observer);

09-29 17:38:35.403 28319-28319/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$2:                                                       onSubscribe09-29 17:38:35.403 28319-28319/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$1:                                                       emit109-29 17:38:35.403 28319-28319/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$2:                                                       onNext109-29 17:38:35.403 28319-28319/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$1:                                                       emit209-29 17:38:35.403 28319-28319/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$2:                                                       onNext2//观察者无法再接收事件                                                       09-29 17:38:35.403 28319-28319/com.junx.rxjava V/meee: class com.junx.rxjava.MainActivity$1:                                                       emit3

subscribe()方法

//绑定观察者和被观察者subscribe(observer);//事件没有人处理subscribe();//消费者:只关心onNext事件的观察者subscribe(consumer);        objectObservable.subscribe(new Consumer<Integer>() {            @Override            public void accept(Integer integer) throws Exception {            //发出的事件被尽数接收                Log.v("meee",getClass()+":\n"+"accept"+integer);            }        });

和Retrofit联合使用

retrofit入门:http://blog.csdn.net/skylakexun/article/details/78140480

public interface API {    @FormUrlEncoded    @POST("login")    //返回Observable对象,LoginModel为接口返回的json的实例化class    Observable<LoginModel> login2(@Field("username") String username, @Field("pwd") String pwd);}

    //Retrofit    private static Retrofit create() {        OkHttpClient.Builder builder = new OkHttpClient().newBuilder();        builder.readTimeout(10, TimeUnit.SECONDS);        builder.connectTimeout(9, TimeUnit.SECONDS);        return new Retrofit.Builder().baseUrl("url/")                .client(builder.build())                .addConverterFactory(GsonConverterFactory.create())                //设置calladapter,将retrofit返回的Call对象转换为Observale对象                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())                .build();    }            Retrofit retrofit = create();        API api = retrofit.create(API.class);        api.login2("123","123456")                .subscribeOn(Schedulers.io())                .observeOn(AndroidSchedulers.mainThread())                .subscribe(new Observer<LoginModel>() {                    @Override                    public void onSubscribe(Disposable d) {                        //获取mDisposable对象,用于防止act退出后rxjava的进程没有结束而导致的崩溃                        mDisposable=d;                    }                    @Override                    public void onNext(LoginModel value) {                    //进行相关的操作                    }                    @Override                    public void onError(Throwable e) {                    }                    @Override                    public void onComplete() {                    }                });

读取数据库

        public Observable<List<Record>> readAllRecords() {            return Observable.create(new ObservableOnSubscribe<List<Record>>() {                @Override                public void subscribe(ObservableEmitter<List<Record>> emitter) throws Exception {                    Cursor cursor = null;                    try {                        cursor = getReadableDatabase().rawQuery("select * from " + TABLE_NAME, new String[]{});                        List<Record> result = new ArrayList<>();                        while (cursor.moveToNext()) {                            result.add(Db.Record.read(cursor));                        }                        emitter.onNext(result);                        emitter.onComplete();                    } finally {                        if (cursor != null) {                            cursor.close();                        }                    }                }            }).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread());        }