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I want to get the three coordinates values of the magnetic field measured by the sensor of my phone. For this, I get a handle to the SensorManager by using sm=(SensorManager)getApplicationContext().getSystemService(Context.SENSOR_SERVICE), then get the sensor with cm=sm.getDefaultSensor(SensorManager.SENSOR_MAGNETIC_FIELD). I then register a SensorEventListener to the SensorManager with sm.registerListener(new SensorListener(),cm,SensorManager.SENSOR_DELAY_UI).

The classSensorListener is a class of my own implementing the SensorEventListener interface. In it's OnSensorChanged method, I get the values from the sensor and I display them. The problem is that I only get the values 1,0 and 0. And they are rarely updated (I have put a counter on the onSensorChanged calls to see how often the update takes place). Changing the time to SENSOR_DELAY_NORMAL doesnot improve anything.

To check if the problem was related to the magnetic sensor, I have added, in the same way, a listener to an accelerometer sensor. The result is very confusing : now, the magnetic sensor generates updates, but not the accelerometer one. And if I remove the accelerometer sensor event listener, I still receive the magnetic sensor events which where missing before adding the accelerometer sensor event listener.(???????????)

Any idea about what is wrong in my code?

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1 回答 1

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只需将它放在一起，它就可以在我的手机（HTC Desire，2.2）上正常工作，请检查您的手机是否遇到此问题......在这种情况下，您的设备可能有问题。

package com.SmartPhoneGizmos.examples.MagSensor;

import android.app.Activity;
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 MagSensorActivity extends Activity  implements SensorEventListener {

    private TextView magneticX;
    private TextView magneticY;
    private TextView magneticZ;
    private SensorManager sensorManager = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
        // Capture magnetic sensor related view elements
        magneticX = (TextView) findViewById(R.id.valMag_X);
        magneticY = (TextView) findViewById(R.id.valMag_Y);
        magneticZ = (TextView) findViewById(R.id.valMag_Z);

        // Register magnetic sensor
        sensorManager.registerListener(this,
                sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD),
                SensorManager.SENSOR_DELAY_NORMAL);
    }

    @Override
    protected void onPause() {
        // Unregister the listener
        sensorManager.unregisterListener(this);
        super.onPause();
    }

    @Override
    protected void onStop() {
        // Unregister the listener
        sensorManager.unregisterListener(this);
        super.onStop();
    }

    @Override
    protected void onResume() {
        super.onResume();

        // Register magnetic sensor
        sensorManager.registerListener(this,
                sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD),
                SensorManager.SENSOR_DELAY_NORMAL);
    }

    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // Ignoring this for now

    }

    public void onSensorChanged(SensorEvent sensorEvent) {
        synchronized (this) {
            if (sensorEvent.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
                magneticX.setText( Float.toString( sensorEvent.values[0]));
                magneticY.setText( Float.toString( sensorEvent.values[1]));
                magneticZ.setText( Float.toString( sensorEvent.values[2]));
            }
        }

    }
}

您的布局文件将需要三个 TextView，valMag_X、valMag_Y、valMag_Z。

于 2011-06-30T15:10:42.470 回答