Question

有人可以举例说明如何使用接近传感器吗？请描述一些事件以及如何使用它们。

Answer 1

每个Android手机都附带传感器来测量各种环境条件。接近传感器测量某个物体距设备的距离。它通常用于检测设备旁边是否存在人脸。

某些接近传感器仅支持二进制近或远测量。在这种情况下，传感器应报告远态的最大范围值和近状态的较小值。

package com.exercise.AndroidProximitySensor;

import android.app.Activity;
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.widget.TextView;

public class AndroidProximitySensorActivity extends Activity {
    /** Called when the activity is first created. */

 TextView ProximitySensor, ProximityMax, ProximityReading;

 SensorManager mySensorManager;
 Sensor myProximitySensor;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ProximitySensor = (TextView)findViewById(R.id.proximitySensor);
        ProximityMax = (TextView)findViewById(R.id.proximityMax);
        ProximityReading = (TextView)findViewById(R.id.proximityReading);

        mySensorManager = (SensorManager)getSystemService(
          Context.SENSOR_SERVICE);
        myProximitySensor = mySensorManager.getDefaultSensor(
          Sensor.TYPE_PROXIMITY);

        if (myProximitySensor == null){
         ProximitySensor.setText("No Proximity Sensor!"); 
        }else{
         ProximitySensor.setText(myProximitySensor.getName());
         ProximityMax.setText("Maximum Range: "
           + String.valueOf(myProximitySensor.getMaximumRange()));
         mySensorManager.registerListener(proximitySensorEventListener,
           myProximitySensor,
           SensorManager.SENSOR_DELAY_NORMAL);
        }
    }

    SensorEventListener proximitySensorEventListener
    = new SensorEventListener(){

  @Override
  public void onAccuracyChanged(Sensor sensor, int accuracy) {
   // TODO Auto-generated method stub

  }

  @Override
  public void onSensorChanged(SensorEvent event) {
   // TODO Auto-generated method stub

   if(event.sensor.getType()==Sensor.TYPE_PROXIMITY){
    ProximityReading.setText("Proximity Sensor Reading:"
      + String.valueOf(event.values[0]));
   }
  }
    };
}

上面代码的布局xml如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<TextView  
    android:id="@+id/proximitySensor"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    />
<TextView  
    android:id="@+id/proximityMax"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    />
<TextView  
    android:id="@+id/proximityReading"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    />
</LinearLayout>

在上面的示例中，我们有3个textview。第一个是显示设备是否支持接近传感器，第二个显示传感器支持的最大范围，第三个显示当前读数。

希望这能让您了解接近传感器的基本知识。

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1 个答案: