Android开发学习之路--传感器之初体验

2022-10-06 10:15:36

说到传感器，还是有很多的，有加速度啊，光照啊，磁传感器等等。当然android手机之所以称为智能手机，少不了这几款传感器的功劳了。下面就学习下了，这里主要学习光照，加速度和磁。

新建工程emSensorStudy，布局如下：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout

    xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical"

    android:layout_margin="5dp"

    tools:context="com.jared.emsensorsstudy.MainActivity">

    <TextView

        android:text="Hello Sensors"

        android:layout_gravity="center"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:textSize="22dp"/>

    <Button

        android:id="@+id/startLightSensor"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="启动LightSensor"

        android:textAllCaps="false"/>

    <Button

        android:id="@+id/startAccelerSensor"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="启动AccelerSensor"

        android:textAllCaps="false"/>

    <Button

        android:id="@+id/startMagneticSensor"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="启动MagneticSensor"

        android:textAllCaps="false"/>

</LinearLayout>

添加LightSensor，AccelerSensor，MagnetiSensor的Activity，修改MainActivity代码如下：

package com.jared.emsensorsstudy;

import android.content.Intent;

import android.os.Bundle;

import android.support.v7.app.AppCompatActivity;

import android.view.View;

import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    private Button startLightSensorBtn;

    private Button startAccelerSensorBtn;

    private Button startMagneticSensorBtn;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        startLightSensorBtn = (Button)findViewById(R.id.startLightSensor);

        startAccelerSensorBtn = (Button)findViewById(R.id.startAccelerSensor);

        startMagneticSensorBtn = (Button)findViewById(R.id.startMagneticSensor);

        startLightSensorBtn.setOnClickListener(new myOnClickListener());

        startAccelerSensorBtn.setOnClickListener(new myOnClickListener());

        startMagneticSensorBtn.setOnClickListener(new myOnClickListener());

    }

    private class myOnClickListener implements View.OnClickListener {

        @Override

        public void onClick(View view) {

            switch (view.getId()) {

                case R.id.startAccelerSensor:

                    Intent intent1 = new Intent(getApplicationContext(), AccelerSensor.class);

                    startActivity(intent1);

                    break;

                case R.id.startLightSensor:

                    Intent intent2 = new Intent(getApplicationContext(), LightSensor.class);

                    startActivity(intent2);

                    break;

                case R.id.startMagneticSensor:

                    Intent intent3 = new Intent(getApplicationContext(), MagneticSensor.class);

                    startActivity(intent3);

                    break;

                default:

                    break;

            }

        }

    }

}

先要实现Light的功能，先修改布局如下：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:layout_margin="10dp"

    tools:context="com.jared.emsensorsstudy.LightSensor">

    <TextView

        android:id="@+id/light_level"

        android:layout_gravity="center"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:textSize="22dp"/>

</LinearLayout>

简单地实现了一个textview用来显示光照强度。接着修改LightSensor代码如下：

package com.jared.emsensorsstudy;

import android.content.Context;

import android.hardware.Sensor;

import android.hardware.SensorEvent;

import android.hardware.SensorEventListener;

import android.hardware.SensorManager;

import android.os.Bundle;

import android.support.v7.app.AppCompatActivity;

import android.widget.TextView;

public class LightSensor extends AppCompatActivity {

    private SensorManager sensorManager;

    private TextView lightLevel;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_light_sensor);

        lightLevel = (TextView)findViewById(R.id.light_level);

        initWithLight();

    }

    @Override

    protected void onDestroy() {

        super.onDestroy();

        if(sensorManager != null) {

            sensorManager.unregisterListener(listener);

        }

    }

    public void initWithLight() {

        sensorManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);

        Sensor sensor = sensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);

        sensorManager.registerListener(listener, sensor, SensorManager.SENSOR_DELAY_NORMAL);

    }

    private SensorEventListener listener = new SensorEventListener() {

        @Override

        public void onSensorChanged(SensorEvent sensorEvent) {

            float value = sensorEvent.values[0];

            lightLevel.setText("Currrent light level is "+value+"lx");

        }

        @Override

        public void onAccuracyChanged(Sensor sensor, int i) {

        }

    };

}

这里先通过getSystemService获取sensor，然后通过注册一个listener来监听传感器的变化，当值有变化的时候会调用onSensorChanged方法，具体运行后，用手遮挡听筒附近的传感器，显示如下：

从上可见光照的效果很明显了。接着我们来试下加速度传感器。这里实现微信摇一摇功能，并且成功了震动。

修改布局如下：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical"

    android:layout_margin="10dp"

    tools:context="com.jared.emsensorsstudy.AccelerSensor">

    <TextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="摇一摇获取更多哦！"

        android:layout_gravity=""

        android:textSize="22dp"/>

    <TextView

        android:id="@+id/shack"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_gravity="center"

        android:textSize="22dp"/>

</LinearLayout>

接着添加代码如下：

package com.jared.emsensorsstudy;

import android.content.Context;

import android.hardware.Sensor;

import android.hardware.SensorEvent;

import android.hardware.SensorEventListener;

import android.hardware.SensorManager;

import android.os.Bundle;

import android.os.Vibrator;

import android.support.v7.app.AppCompatActivity;

import android.widget.TextView;

public class AccelerSensor extends AppCompatActivity {

    private SensorManager sensorManager;

    private TextView shackPhone;

    private Vibrator vibrator;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_acceler_sensor);

        shackPhone = (TextView)findViewById(R.id.shack);

        initWithAcceler();

    }

    @Override

    protected void onDestroy() {

        super.onDestroy();

        if(sensorManager != null) {

            sensorManager.unregisterListener(listener);

        }

    }

    private void initWithAcceler() {

        sensorManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);

        Sensor sensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);

        sensorManager.registerListener(listener, sensor, SensorManager.SENSOR_DELAY_NORMAL);

        vibrator = (Vibrator)getSystemService(Context.VIBRATOR_SERVICE);

    }

    private SensorEventListener listener = new SensorEventListener() {

        @Override

        public void onSensorChanged(SensorEvent sensorEvent) {

            float xValue = Math.abs(sensorEvent.values[0]);

            float yValue = Math.abs(sensorEvent.values[1]);

            float zValue = Math.abs(sensorEvent.values[2]);

            int medumValue = 19;

            if(xValue > medumValue || yValue > medumValue || zValue > medumValue) {

                vibrator.vibrate(200);

                shackPhone.setText("恭喜你摇一摇成功，新年快乐！");

            } else {

                //Toast.makeText(getApplicationContext(), "请使劲摇哦！", Toast.LENGTH_SHORT).show();

            }

        }

        @Override

        public void onAccuracyChanged(Sensor sensor, int i) {

        }

    };

}

这里的代码和LightSensor的代码差不多，主要是当三个方向的加速度大于19的时候就表示在摇动了，然后震动下手机就ok了。效果如下：

最后来学习下magneticSensor了。这里实现个compass。首先就是提供一张图片了，修改布局如下：

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:layout_margin="10dp"

    tools:context="com.jared.emsensorsstudy.MagneticSensor">

    <ImageView

        android:id="@+id/compass_img"

        android:layout_width="250dp"

        android:layout_height="250dp"

        android:layout_centerInParent="true"

        android:src="@drawable/compass" />

</RelativeLayout>

接着就是修改MagneticSensor的代码了：

package com.jared.emsensorsstudy;

import android.content.Context;

import android.hardware.Sensor;

import android.hardware.SensorEvent;

import android.hardware.SensorEventListener;

import android.hardware.SensorManager;

import android.os.Bundle;

import android.support.v7.app.AppCompatActivity;

import android.view.animation.Animation;

import android.view.animation.RotateAnimation;

import android.widget.ImageView;

public class MagneticSensor extends AppCompatActivity {

    private SensorManager sensorManager;

    private ImageView compassImage;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_magnetic_sensor);

        compassImage = (ImageView)findViewById(R.id.compass_img);

        initWithCompass();

    }

    @Override

    protected void onDestroy() {

        super.onDestroy();

        sensorManager.unregisterListener(listener);

    }

    private void initWithCompass() {

        sensorManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);

        Sensor magneticSensor = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);

        Sensor acclerSensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);

        sensorManager.registerListener(listener, magneticSensor, SensorManager.SENSOR_DELAY_GAME);

        sensorManager.registerListener(listener, acclerSensor, SensorManager.SENSOR_DELAY_GAME);

    }

    private SensorEventListener listener = new SensorEventListener() {

        float[] acclerValues = new float[3];

        float[] magneticValues = new float[3];

        private float lastRotateDegree;

        @Override

        public void onSensorChanged(SensorEvent sensorEvent) {

            switch (sensorEvent.sensor.getType()) {

                case Sensor.TYPE_ACCELEROMETER:

                    acclerValues = sensorEvent.values.clone();

                    break;

                case Sensor.TYPE_MAGNETIC_FIELD:

                    magneticValues = sensorEvent.values.clone();

                    break;

                default:

                    break;

            }

            float[] values = new float[3];

            float[] R = new float[9];

            //调用getRotaionMatrix获得变换矩阵R[]

            SensorManager.getRotationMatrix(R, null, acclerValues, magneticValues);

            SensorManager.getOrientation(R, values);

            //经过SensorManager.getOrientation(R, values);得到的values值为弧度

            //转换为角度

            float rotateDegree = -(float)Math.toDegrees(values[0]);

            if(Math.abs(rotateDegree - lastRotateDegree) > 2) {

                RotateAnimation animation = new RotateAnimation(

                  lastRotateDegree, rotateDegree, Animation.RELATIVE_TO_SELF, 0.5f,

                        Animation.RELATIVE_TO_SELF, 0.5f);

                animation.setFillAfter(true);

                compassImage.startAnimation(animation);

                lastRotateDegree = rotateDegree;

            }

        }

        @Override

        public void onAccuracyChanged(Sensor sensor, int i) {

        }

    };

}

这里通过加速度和磁传感器来实现一个方向，因为方向传感器官方已经不提倡使用了。运行效果如下：

传感器就先学习这些了。

附：参考《第一行代码》

码农公寓

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