一、什么是 RxJava?
RxJava 是一个响应式编程框架,采用观察者设计模式。所以自然少不了 Observable 和 Subscriber 这两个东东了。
RxJava 是一个开源项目,地址:https://github.com/ReactiveX/RxJava
还有一个RxAndroid,用于 Android 开发,添加了 Android 用的接口。地址:https://github.com/ReactiveX/RxAndroid
二、例子
通过请求openweathermap 的天气查询接口返回天气数据
1、增加编译依赖
dependencies {
compile fileTree(dir: ‘libs’, include: [‘*.jar’])
compile ‘com.android.support:appcompat-v7:22.0.0’
compile ‘io.reactivex:rxjava:1.0.9’
compile ‘io.reactivex:rxandroid:0.24.0’
compile ‘com.squareup.retrofit:retrofit:1.9.0’
}
retrofit 是一个 restful 请求客户端。详见:http://square.github.io/retrofit/
2、服务器接口
/**
- 接口
- Created by Hal on 15/4/26.
*/
public class ApiManager {
private static final String ENDPOINT = “http://api.openweathermap.org/data/2.5“;
/**
- 服务接口
*/
private interface ApiManagerService {
@GET(“/weather”)
WeatherData getWeather(@Query(“q”) String place, @Query(“units”) String units);
}
private static final RestAdapter restAdapter = new RestAdapter.Builder().setEndpoint(ENDPOINT).setLogLevel(RestAdapter.LogLevel.FULL).build();
private static final ApiManagerService apiManager = restAdapter.create(ApiManagerService.class);
/**
- 将服务接口返回的数据,封装成{@link rx.Observable}
- @param city
- @return
*/
public static ObservablegetWeatherData(final String city) {
return Observable.create(new Observable.OnSubscribe() {
@Override
public void call(Subscriber<? super WeatherData> subscriber) {
//订阅者回调 onNext 和 onCompleted
subscriber.onNext(apiManager.getWeather(city, “metric”));
subscriber.onCompleted();
}
}).subscribeOn(Schedulers.io());
}
}
订阅者的回调有三个方法,onNext,onError,onCompleted
3、接口调用
/**
- 多个 city 请求
- map,flatMap 对 Observable进行变换
/
Observable.from(CITIES).flatMap(new Func1>() { onNext/new Action1
@Override
public Observablecall(String s) {
return ApiManager.getWeatherData(s);
}
}).subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(/() { onError*/new Action1
@Override
public void call(WeatherData weatherData) {
Log.d(LOG_TAG, weatherData.toString());
}
}, /() {
@Override
public void call(Throwable throwable) {
}
});
/**
- 单个 city 请求
*/
ApiManager.getWeatherData(CITIES[0]).subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Action1() {
@Override
public void call(WeatherData weatherData) {
Log.d(LOG_TAG, weatherData.toString());
((TextView) findViewById(R.id.text)).setText(weatherData.toString());
}
}, new Action1() {
@Override
public void call(Throwable throwable) {
Log.e(LOG_TAG, throwable.getMessage(), throwable);
}
});
/**
- Android View 事件处理
*/
ViewObservable.clicks(findViewById(R.id.text), false).subscribe(new Action1() {
@Override
public void call(OnClickEvent onClickEvent) {
}
});
subscribeOn(Schedulers.io())与observeOn(AndroidSchedulers.mainThread())分别定义了这两个动作的线程。Android UI 更新需要在主线程。
4、retrofit 支持 rxjava 整合
/**
- 服务接口
*/
private interface ApiManagerService {
@GET(“/weather”)
WeatherData getWeather(@Query(“q”) String place, @Query(“units”) String units);
/**
- retrofit 支持 rxjava 整合
- 这种方法适用于新接口
*/
@GET(“/weather”)
ObservablegetWeatherData(@Query(“q”) String place, @Query(“units”) String units);
}
Demo 代码: https://github.com/foolingdutchman/EverExample