Andorid传感器之摇一摇

package com.llm;

import java.util.List;

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.Toast;

public class TestSensorActivity
    extends Activity {
    private static final int FORCE_THRESHOLD = 900;
    private long lastShakeTime;//
    private long presentShakeTime;
    private long duration;// 时间差
    private float lastX = 0.0f;
    private float lastY = 0.0f;
    private float lastZ = 0.0f;
    private float presentX = 0.0f;
    private float presentY = 0.0f;
    private float presentZ = 0.0f;
    private float currenForce;// 摇动的速率

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        SensorManager sm = (SensorManager) getSystemService(SENSOR_SERVICE);
        List<Sensor> ls = sm.getSensorList(Sensor.TYPE_ACCELEROMETER);
        if (ls.size() > 0) {
            Sensor s = ls.get(0);
            sm.registerListener(new SensorEventListener() {

                public void onSensorChanged(SensorEvent event) {
                    // 如果有一个条件为真则return
                    if (event.sensor.getType() != Sensor.TYPE_ACCELEROMETER || event.values.length < 3)
                        return;
                    presentX = event.values[SensorManager.DATA_X];
                    presentY = event.values[SensorManager.DATA_Y];
                    presentZ = event.values[SensorManager.DATA_Z];
                    presentShakeTime = System.currentTimeMillis();
                    if (presentShakeTime - lastShakeTime > 100) {
                        duration = (presentShakeTime - lastShakeTime);
                        lastShakeTime = presentShakeTime;
                        currenForce =
                            Math.abs(presentX + presentY + presentZ - lastX - lastY - lastZ) / duration *
                                10000;
                        if (currenForce > FORCE_THRESHOLD) {// 摇动的速率>900
                            Toast.makeText(TestSensorActivity.this, "摇一摇成功", 1000).show();
                        }
                        lastX = presentX;
                        lastY = presentY;
                        lastZ = presentZ;
                    }
                };

                public void onAccuracyChanged(Sensor sensor, int accuracy) {

                }
            }, s, SensorManager.SENSOR_DELAY_NORMAL);
        }
    }
}