使用 RxJava 监控设备硬件传感器的 Android 库_java_代码_相关文件_下载

# ReactiveSensors [](http://android-arsenal.com/details/1/2451) Android library monitoring hardware sensors with RxJava. | Current Branch | Branch | Artifact Id | CI Build Status | Maven Central | |:--------------:|:-------:|:-----------:|:---------------:|:-------------:| | | [`RxJava1.x`](https://github.com/pwittchen/ReactiveSensors/tree/RxJava1.x) | `reactivesensors` |  |  | | | [`RxJava2.x`](https://github.com/pwittchen/ReactiveSensors/tree/RxJava2.x) | `reactivesensors-rx2` |  |  | | :ballot_box_with_check: | [`RxJava3.x`](https://github.com/pwittchen/ReactiveSensors/tree/RxJava3.x) | `reactivesensors-rx3` |  |  | Contents -------- - [Usage](#usage) - [Setting sampling period](#setting-sampling-period) - [Example](#example) - [Good practices](#good-practices) - [Checking whether sensor exists](#checking-whether-sensor-exists) - [Letting it crash](#letting-it-crash) - [Subscribing and disposing flowables](#subscribing-and-disposing-flowables) - [Filtering stream](#filtering-stream) - [Writing tests](#writing-tests) - [Other practices](#other-practices) - [Download](#download) - [Tests](#tests) - [Code style](#code-style) - [Static code analysis](#static-code-analysis) - [References](#references) - [License](#license) Usage ----- Code sample below demonstrates how to observe Gyroscope sensor. Please note that we are filtering events occurring when sensor readings change with `ReactiveSensorEvent::sensorChanged` method. There's also event describing change of sensor's accuracy, which can be filtered with `ReactiveSensorEvent::accuracyChanged` method. When we don't apply any filter, we will be notified both about sensor readings and accuracy changes. ```java new ReactiveSensors(context).observeSensor(Sensor.TYPE_GYROSCOPE) .subscribeOn(Schedulers.computation()) .filter(ReactiveSensorEvent::sensorChanged) .observeOn(AndroidSchedulers.mainThread()) .subscribe(new Consumer<ReactiveSensorEvent>() { @Override public void call(ReactiveSensorEvent event) { float x = event.sensorValues()[0]; float y = event.sensorValues()[1]; float z = event.sensorValues()[2]; String message = String.format("x = %f, y = %f, z = %f", x, y, z); Log.d("gyroscope readings", message); } }); } ``` We can observe any hardware sensor in the same way. You can check [list of all sensors in official Android documentation](http://developer.android.com/guide/topics/sensors/sensors_overview.html#sensors-intro). To get list of all sensors available on the current device, you can use `getSensors()` method available in `ReactiveSensors` class. ### Setting sampling period Default sampling period for `Flowable` below is set to `SensorManager.SENSOR_DELAY_NORMAL`. ```java Flowable<ReactiveSensorEvent> observeSensor(int sensorType) ``` We can configure sampling period according to our needs with the following flowable: ```java Flowable<ReactiveSensorEvent> observeSensor(final int sensorType, final int samplingPeriodInUs) ``` We can use predefined values available in `SensorManager` class from Android SDK: - `int SENSOR_DELAY_FASTEST` - get sensor data as fast as possible - `int SENSOR_DELAY_GAME` - rate suitable for games - `int SENSOR_DELAY_NORMAL` - rate (default) suitable for screen orientation changes - `int SENSOR_DELAY_UI` - rate suitable for the user interface We can also define our own integer value in microseconds, but it's recommended to use predefined values. We can customize RxJava Backpressure Strategy for our flowable with method: ```java Flowable<ReactiveSensorEvent> observeSensor(final int sensorType, final int samplingPeriodInUs, final BackpressureStrategy strategy) ``` Default Backpressure Strategy is `BUFFER`. Example ------- Exemplary application, which gets readings of various sensors is located in `app` directory of this repository. You can easily change `SENSOR_TYPE` variable to read values from a different sensor in a given samples. Good practices -------------- ### Checking whether sensor exists We should check whether device has concrete sensor before we start observing it. We can do it in the following way: ```java if (reactiveSensors.hasSensor(SENSOR_TYPE)) { // observe sensor } else { // show error message } ``` ### Letting it crash We can let our subscription crash and handle situation when device does not have given sensor e.g. in the `Consumer<Throwable>()` implementation (if we want to return `Disposable`) or in the `onError(throwable)` method implementation of the `Subscriber`. Other types of errors can be handled there as well. ```java new ReactiveSensors(context).observeSensor(Sensor.TYPE_GYROSCOPE) .subscribeOn(Schedulers.computation()) .filter(ReactiveSensorEvent::sensorChanged) .observeOn(AndroidSchedulers.mainThread()) .subscribe(new Consumer<ReactiveSensorEvent>() { @Override public void accept(ReactiveSensorEvent reactiveSensorEvent) throws Exception { // handle reactiveSensorEvent } }, new Consumer<Throwable>() { @Override public void accept(Throwable throwable) throws Exception { if (throwable instanceof SensorNotFoundException) { textViewForMessage.setText("Sorry, your device doesn't have required sensor."); } } }); ``` ### Subscribing and disposing flowables When we are using Disposables in Activity, we should subscribe them in `onResume()` method and dispose them in `onPause()` method. ### Filtering stream When we want to receive **only sensor updates**, we should use `ReactiveSensorEvent::sensorChanged` method in `filter(...)` method from RxJava. When we want to receive **only accuracy updates**, we should use `ReactiveSensorEvent::accuracyChanged` method in `filter(...)` method from RxJava. If we don't apply any filter, we will receive both accuracy and sensor readings updates. ### Writing tests `ReactiveSensors` class implements `SensorsProxy` interface. It allows you to create stubs or mocks for testing behavior of the sensors in your application without need of mocking `SensorManager` class from Android SDK accessing hardware components. Once you instantiate `SensorsProxy`, then you'll be allowed to mock or stub it pretty easily. Moreover, you can mock `ReactiveSensorEvent`, which wraps code from Android API, expose appropriate methods and does not force you to use native code accessing hardware sensors in tests, so you can foucus just on the application logic. ### Other practices See also [Best Practices for Accessing and Using Sensors](http://developer.android.com/guide/topics/sensors/sensors_overview.html#sensors-practices). Download -------- latest version:  replace `x.y.z` with the latest version You can depend on the library through Maven: ```xml <dependency> <groupId>com.github.pwittchen</groupId> <artifactId>reactivesensors-rx3</artifactId> <version>x.y.z</version> </dependency> ``` or through Gradle: ```groovy dependencies { compile 'com.github.pwittchen:reactivesensors-rx3:x.y.z' } ``` Tests