Demo地址

RxJava2Demo

本Demo旨在帮助从未接触过RxJava的同学直接入坑RxJava2，如丝般顺滑，万水千山总是情，留个star行不行？

RxJava & RxAndroid （2.0版）#

定义

RxJava – Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.

一个在 Java VM 上使用可观测的序列来组成异步的、基于事件的程序的库

初学者如果看到这个准确但晦涩的定义肯定一脸懵逼，不过我们我们只要把握重点即可：

异步
基于事件
观察者模式

RxAndroid - Android specific bindings for RxJava 2.This module adds the minimum classes to RxJava that make writing reactive components in Android applications easy and hassle-free.

RxAndroid在RxJava的基础上添加了最少的类使得开发Android应用中的响应式组件更加的容易和自由

特点

简洁，并不是指代码量上的那种简洁，而是逻辑上的简洁，随着程序逻辑变得越来越复杂，它依然能够保持简洁。

Github

RxJava
RxAndroid

Hello world

添加依赖

compile 'io.reactivex.rxjava2:rxandroid:2.0.1'
compile 'io.reactivex.rxjava2:rxjava:2.0.1'

简单版本

//简单版本
private void helloWorldSimple() {
    //创建消费者，消费者接受一个String类型的事件
    Consumer consumer = new Consumer() {
        @Override
        public void accept(String s) throws Exception {
            Log.d(TAG, s);
        }
    };
    //被观察者发出Hello World, 并且指定该事件的消费者为consumer
    Observable.just("Hello World").subscribe(consumer);
}

运行结果

D/MainActivity: Hello World

复杂版本

private void helloWorldComplex() {
    //Observer可以看做Consumer的完整版
    Observer observer = new Observer() {

        //当Observable调用subscribe方法时会回调该方法
        @Override
        public void onSubscribe(Disposable d) {
            Log.d(TAG, "onSubscribe: ");
        }

        //onSubscribe方法后调用
        @Override
        public void onNext(String value) {
            Log.d(TAG, "onNext: " + value);
        }
        //这里没有出错，没有被调用
        @Override
        public void onError(Throwable e) {
            Log.d(TAG, "onError: ");
        }

        //onNext之后调用
        @Override
        public void onComplete() {
            Log.d(TAG, "onComplete: ");
        }
    };
    //被观察者发出Hello World, 并且指定该事件的观察者为observer
    Observable.just("Hello World").subscribe(observer);
}

运行结果

D/MainActivity: onSubscribe: 
D/MainActivity: onNext: Hello World
D/MainActivity: onComplete:

变态版本

private void helloWorldPlus() {
    //创建一个观察者
    Observer observer = new Observer() {

        //当Observable调用subscribe方法时会回调该方法
        @Override
        public void onSubscribe(Disposable d) {
            Log.d(TAG, "onSubscribe: ");
        }

        //onSubscribe方法后调用
        @Override
        public void onNext(String value) {
            Log.d(TAG, "onNext: " + value);
        }
        //这里没有出错，没有被调用
        @Override
        public void onError(Throwable e) {
            Log.d(TAG, "onError: ");
        }

        //onNext之后调用
        @Override
        public void onComplete() {
            Log.d(TAG, "onComplete: ");
        }
    };
    
    //创建一个Observable
    Observable observable = Observable.create(new ObservableOnSubscribe() {

        @Override
        public void subscribe(ObservableEmitter e) throws Exception {
            e.onNext("Hello World");//会调用到观察者的onNext
            e.onComplete();//会调用到观察者的onComplete
        }
    });

    observable.subscribe(observer);
}

运行结果

D/MainActivity: onSubscribe: 
D/MainActivity: onNext: Hello World
D/MainActivity: onComplete:

filter操作符

你早上去吃早餐，师傅是被观察者，说咱这有包子，馒头，肠粉，春卷，饺子，炒粉，你仔细想了想，发现你是最喜欢饺子的，所以把其他的都排除掉，于是你就吃到了饺子。

private void filter() {
    //把Consumer可以看做精简版的Observer
    Consumer consumer = new Consumer() {
        //accept可以简单的看做onNext
        @Override
        public void accept(String s) throws Exception {
            Log.d(TAG, "accept: " + s);//这里只能吃上饺子
        }
    };

    Observable.just("包子", "馒头", "肠粉", "春卷", "饺子", "炒粉")
            .filter(new Predicate() {
                @Override
                public boolean test(String s) throws Exception {
                    Log.d(TAG, "test: " + s);
                    return s.equals("饺子");//只允许饺子通过测试
                }
            })
            .subscribe(consumer);
}

运行结果

D/MainActivity: test: 包子
D/MainActivity: test: 馒头
D/MainActivity: test: 肠粉
D/MainActivity: test: 春卷
D/MainActivity: test: 饺子
D/MainActivity: accept: 饺子
D/MainActivity: test: 炒粉

map操作符

map操作符能够完成数据类型的转换。以下代码展示了一个Student到Developer的转换。

private void map() {
    Observer observer = new Observer() {
        @Override
        public void onSubscribe(Disposable d) {
            Log.d(TAG, "onSubscribe: ");
        }

        //观察者接收到一个Developer
        @Override
        public void onNext(Developer value) {
            Log.d(TAG, "onNext: "  + value.toString());
        }

        @Override
        public void onError(Throwable e) {
            Log.d(TAG, "onError: ");
        }

        @Override
        public void onComplete() {
            Log.d(TAG, "onComplete: ");
        }
    };
    
    Student student = new Student();
    student.setName("Leon");
    student.setAge(18);
    //map操作符，从Student类型转换成Developer
    Observable.just(student).map(new Function() {
        @Override
        public Developer apply(Student student) throws Exception {
            Log.d(TAG, "apply: " + student.toString());
            Developer developer = new Developer();
            developer.setName(student.getName());
            developer.setAge(student.getAge());
            developer.setSkill("Android");
            return developer;
        }
    }).subscribe(observer);
}

运行结果

D/MainActivity: onSubscribe: 
D/MainActivity: apply: Student{name='Leon', age=18}
D/MainActivity: onNext: Developer{name='Leon', age=18, skill='Android'}
D/MainActivity: onComplete:

flatmap操作符

flatmap能够链式地完成数据类型的转换和加工。

遍历一个学校中所有班级所有学生

private void flatmapClassToStudent() {

    Observable.fromIterable(new School().getClasses())

            //输入是Class类型，输出是ObservableSource类型
            .flatMap(new Function>() {

                //输入是Class类型，输出是ObservableSource类型
                @Override
                public ObservableSource apply(Class aClass) throws Exception {
                    Log.d(TAG, "apply: " + aClass.toString());
                    return Observable.fromIterable(aClass.getStudents());
                }
            }).subscribe(
            new Observer() {
                @Override
                public void onSubscribe(Disposable d) {
                    Log.d(TAG, "onSubscribe: ");
                }

                @Override
                public void onNext(Student value) {
                    Log.d(TAG, "onNext: " + value.toString());
                }

                @Override
                public void onError(Throwable e) {

                }

                @Override
                public void onComplete() {

                }
            });
}

运行结果

D/MainActivity: onSubscribe: 
D/MainActivity: apply: Class0
D/MainActivity: onNext: Student{name='Class0_0', age=18}
D/MainActivity: onNext: Student{name='Class0_1', age=18}
D/MainActivity: onNext: Student{name='Class0_2', age=18}
D/MainActivity: apply: Class1
D/MainActivity: onNext: Student{name='Class1_0', age=18}
D/MainActivity: onNext: Student{name='Class1_1', age=18}
D/MainActivity: onNext: Student{name='Class1_2', age=18}
D/MainActivity: apply: Class2
D/MainActivity: onNext: Student{name='Class2_0', age=18}
D/MainActivity: onNext: Student{name='Class2_1', age=18}
D/MainActivity: onNext: Student{name='Class2_2', age=18}

遍历一个学校所有班级所有组的所有学生

private void flatmapClassToGroupToStudent() {
    Observable.fromIterable(new School().getClasses())
            //输入是Class类型，输出是ObservableSource类型
            .flatMap(new Function>() {
                @Override
                public ObservableSource apply(Class aClass) throws Exception {
                    Log.d(TAG, "apply: " + aClass.toString());
                    return Observable.fromIterable(aClass.getGroups());
                }
            })
            //输入类型是Group，输出类型是ObservableSource类型
            .flatMap(new Function>() {
                @Override
                public ObservableSource apply(Group group) throws Exception {
                    Log.d(TAG, "apply: " + group.toString());
                    return Observable.fromIterable(group.getStudents());
                }
            })
            .subscribe(
                    new Observer() {
                        @Override
                        public void onSubscribe(Disposable d) {
                            Log.d(TAG, "onSubscribe: ");
                        }

                        @Override
                        public void onNext(Student value) {
                            Log.d(TAG, "onNext: " + value.toString());
                        }

                        @Override
                        public void onError(Throwable e) {

                        }

                        @Override
                        public void onComplete() {

                        }
                    });
}

运行结果

D/MainActivity: onSubscribe: 
D/MainActivity: apply: Class0
D/MainActivity: apply: Group0
D/MainActivity: onNext: Student{name='Group0_0', age=18}
D/MainActivity: onNext: Student{name='Group0_1', age=18}
D/MainActivity: onNext: Student{name='Group0_2', age=18}
D/MainActivity: apply: Group1
D/MainActivity: onNext: Student{name='Group1_0', age=18}
D/MainActivity: onNext: Student{name='Group1_1', age=18}
D/MainActivity: onNext: Student{name='Group1_2', age=18}
D/MainActivity: apply: Group2
D/MainActivity: onNext: Student{name='Group2_0', age=18}
D/MainActivity: onNext: Student{name='Group2_1', age=18}
D/MainActivity: onNext: Student{name='Group2_2', age=18}
D/MainActivity: apply: Class1
D/MainActivity: apply: Group0
D/MainActivity: onNext: Student{name='Group0_0', age=18}
D/MainActivity: onNext: Student{name='Group0_1', age=18}
D/MainActivity: onNext: Student{name='Group0_2', age=18}
D/MainActivity: apply: Group1
D/MainActivity: onNext: Student{name='Group1_0', age=18}
D/MainActivity: onNext: Student{name='Group1_1', age=18}
D/MainActivity: onNext: Student{name='Group1_2', age=18}
D/MainActivity: apply: Group2
D/MainActivity: onNext: Student{name='Group2_0', age=18}
D/MainActivity: onNext: Student{name='Group2_1', age=18}
D/MainActivity: onNext: Student{name='Group2_2', age=18}
D/MainActivity: apply: Class2
D/MainActivity: apply: Group0
D/MainActivity: onNext: Student{name='Group0_0', age=18}
D/MainActivity: onNext: Student{name='Group0_1', age=18}
D/MainActivity: onNext: Student{name='Group0_2', age=18}
D/MainActivity: apply: Group1
D/MainActivity: onNext: Student{name='Group1_0', age=18}
D/MainActivity: onNext: Student{name='Group1_1', age=18}
D/MainActivity: onNext: Student{name='Group1_2', age=18}
D/MainActivity: apply: Group2
D/MainActivity: onNext: Student{name='Group2_0', age=18}
D/MainActivity: onNext: Student{name='Group2_1', age=18}
D/MainActivity: onNext: Student{name='Group2_2', age=18}

线程调度

关于RxJava的线程调度，初学者只需要掌握两个api就够够的啦。

subscribeOn

指定Observable在一个指定的线程调度器上创建。只能指定一次，如果指定多次则以第一次为准

observeOn

指定在事件传递，转换，加工和最终被观察者接受发生在哪一个线程调度器。可指定多次，每次指定完都在下一步生效。

常用线程调度器类型

Schedulers.single() 单线程调度器，线程可复用
Schedulers.newThread() 为每个任务创建新的线程
Schedulers.io() 处理io密集型任务，内部是线程池实现，可自动根据需求增长
Schedulers.computation() 处理计算任务，如事件循环和回调任务
AndroidSchedulers.mainThread() Android主线程调度器

示例

private void scheduleThreads() {
    Observable.create(
            new ObservableOnSubscribe() {
                @Override
                public void subscribe(ObservableEmitter e) throws Exception {
                    Log.d(TAG, "subscribe: " + Thread.currentThread().getName());
                    e.onNext("Hello Leon Fan");
                    e.onComplete();
                }
            })
            //指定subscribe方法在io线程池中调用
            .subscribeOn(Schedulers.io())
            //指定onNext方法 onComplete的方法在新建的线程中调用
            .observeOn(Schedulers.newThread())
            .subscribe(
                    new Observer() {
                        @Override
                        public void onSubscribe(Disposable d) {
                            Log.d(TAG, "onSubscribe: " + Thread.currentThread().getName());
                        }

                        @Override
                        public void onNext(String value) {
                            Log.d(TAG, "onNext: " + Thread.currentThread().getName() + " " + value);
                        }

                        @Override
                        public void onError(Throwable e) {

                        }

                        @Override
                        public void onComplete() {
                            Log.d(TAG, "onComplete: " + Thread.currentThread().getName());
                        }
                    });

}

运行结果

D/MainActivity: onSubscribe: main
D/MainActivity: subscribe: RxCachedThreadScheduler-4
D/MainActivity: onNext: RxNewThreadScheduler-1 Hello Leon Fan
D/MainActivity: onComplete: RxNewThreadScheduler-1

如果将示例中的.observeOn(Schedulers.newThread())改成AndroidSchedulers.mainThread()，则运行结果如下：

D/MainActivity: onSubscribe: main
D/MainActivity: subscribe: RxCachedThreadScheduler-5
D/MainActivity: onNext: main Hello Leon Fan
D/MainActivity: onComplete: main

RxJava与Retrofit集成

我们做一个Demo通过网络请求获取豆瓣电影Top10的列表来展示RxJava和Retrofit的集成的姿势。

movielistactivity.png

Retrofit集成

添加依赖

compile 'com.squareup.retrofit2:retrofit:2.1.0'
compile 'com.squareup.retrofit2:converter-gson:2.1.0'
//compile 'com.squareup.retrofit2:adapter-rxjava:2.1.0' 官方adapter仅支持rxjava1.0
compile 'com.jakewharton.retrofit:retrofit2-rxjava2-adapter:1.0.0'

创建网络接口

public interface Api {
    @GET("top250")
    Observable listTop250(@Query("start") int start, @Query("count") int count);
}

实现Api

public class MovieRetrofit {

    private static MovieRetrofit sMovieRetrofit;
    private final Api mApi;

    public static MovieRetrofit getInstance() {
        if (sMovieRetrofit == null) {
            synchronized (MovieRetrofit.class) {
                if (sMovieRetrofit == null) {
                    sMovieRetrofit = new MovieRetrofit();
                }
            }
        }
        return sMovieRetrofit;
    }

    private MovieRetrofit() {
        Retrofit retrofit = new Retrofit.Builder().baseUrl("https://api.douban.com/v2/movie/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .build();
        mApi = retrofit.create(Api.class);
    }

    public Api getApi() {
        return mApi;
    }
}

发送网络请求刷新列表




Observable movieBeanObservable = MovieRetrofit.getInstance().getApi().listTop250(0, 10);
movieBeanObservable.subscribeOn(Schedulers.io())//在io线程池中执行map
        //将网络的结果转换成我们要的电影名的列表
        .map(new Function>() {
            @Override
            public List apply(MovieBean movieBean) throws Exception {
                List array = new ArrayList();
                for (int i = 0; i < movieBean.getSubjects().size(); i++) {
                    String title = movieBean.getSubjects().get(i).getTitle();
                    array.add(title);
                }
                return array;
            }
        })
        .observeOn(AndroidSchedulers.mainThread())//在主线程中执行onNext
        .subscribe(new Observer>() {
                
        ......

            @Override
            public void onNext(List value) {
                ArrayAdapter arrayAdapter = new ArrayAdapter(MovieListActivity.this, android.R.layout.simple_list_item_1, value);
                setListAdapter(arrayAdapter);
            }
            ......
        });

参考

本人旨在帮助从未接触过RxJava的童鞋直接入坑RxJava2.0，更多使用姿势请自行参考其他资料学习。

给Android开发者的Rx详解
RxJava2-Android-Samples
关于 RxJava 最友好的文章—— RxJava 2.0 全新来袭

RxJava2轻松入门

Demo地址

RxJava & RxAndroid （2.0版）#

定义

特点

Github

Hello world

添加依赖

简单版本

运行结果

复杂版本

运行结果

变态版本

运行结果

filter操作符

运行结果

map操作符

运行结果

flatmap操作符

遍历一个学校中所有班级所有学生

运行结果

遍历一个学校所有班级所有组的所有学生

运行结果

线程调度

subscribeOn

observeOn

常用线程调度器类型

示例

运行结果

RxJava与Retrofit集成

Retrofit集成

添加依赖

创建网络接口

实现Api

发送网络请求刷新列表

参考

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