Demo地址
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
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。
