问题
So I have the code below which I can't get to work. I am trying to have one class (AccelerometerReader) read the values of my phone's accelerometer, and then I call those values in another class (MyGame), which I use to print those values on the screen. Everything in the code seems fine, and I don't get any values, except the values that I print all just say 0.0, and don't change. I know for a fact my phone has an accelerometer too. Any help would be appreciated!
Thanks, Owen
AccelerometerReader Class
import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
public class AccelerometerReader extends Activity implements SensorEventListener{
private SensorManager sensorManager;
float ax,ay,az; // these are the acceleration in x, y and z axes
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
sensorManager=(SensorManager) getSystemService(SENSOR_SERVICE);
sensorManager.registerListener(this, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
@Override
public void onSensorChanged(SensorEvent event) {
if (event.sensor.getType() != Sensor.TYPE_ACCELEROMETER)
return;
if (event.sensor.getType()==Sensor.TYPE_ACCELEROMETER){
ax=event.values[0];
ay=event.values[1];
az=event.values[2];
}
}
public float getValueX() {
return ax;
}
public float getValueY() {
return ay;
}
public float getValueZ() {
return az;
}
}
Inside MyGame Class
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
leftWall = new Rect(-100,0,0,canvas.getHeight());
rightWall = new Rect(canvas.getWidth(), 0, (canvas.getWidth() + 100), canvas.getHeight());
floor = new Rect(0,canvas.getHeight(),canvas.getWidth(),(canvas.getHeight() + 100));
ceiling = new Rect(0,-100,canvas.getWidth(),0);
AccelerometerReader acc = new AccelerometerReader();
float ax = acc.getValueX();
float ay = acc.getValueY();
float az = acc.getValueZ();
canvas.drawColor(Color.rgb(red,green,blue)); //0 or 51?, 51, 102
Rect player = new Rect(xPos,yPos,xPos+100,yPos+100);
Paint myPaint = new Paint();
myPaint.setColor(Color.rgb(0, 102, 255));
canvas.drawRect(player, myPaint);
myPaint.setColor(Color.rgb(0, 0, 0));
canvas.drawRect(xPos + 5, yPos + 5, xPos + 95, yPos +95, myPaint);
myPaint.setColor(Color.WHITE);
myPaint.setTextSize(20);
canvas.drawText("" + Math.round(ySpeed), 75, 50, myPaint);
canvas.drawText(ax +", "+ ay +", "+ az, 300, 50, myPaint);
if(gameStarted == false) {
myPaint.setTextSize(30);
myPaint.setTextAlign(Align.CENTER);
canvas.drawText("Touch screen to begin!", canvas.getWidth()/2, canvas.getHeight()/2, myPaint);
}
int r = Math.round(rand.nextInt(canvas.getHeight() - 150));
if(needsRand == true) {
blockY = r;
myPaint.setColor(Color.rgb(rand.nextInt(255), rand.nextInt(255), rand.nextInt(255)));
}
//if(isAlive == true) {
Rect block = new Rect(blockX,blockY,(blockX+100),(blockY+100)); // left, top, right, bottom
myPaint.setColor(Color.WHITE);
canvas.drawRect(block, myPaint);
blockX--;
//}
if(player.intersect(leftWall)) {
xSpeed = Math.abs(xSpeed);
} else if(player.intersect(rightWall)) {
xSpeed = -(xSpeed);
} else if(player.intersect(floor)) {
yPos = canvas.getHeight() - 150;
ySpeed = -(ySpeed)*.75;
} else if(player.intersect(ceiling)) {
ySpeed = Math.abs(ySpeed);
} else if(player.intersect(block)) {
ySpeed = 0;
}
if(blockX <= -100) {
blockX = canvas.getWidth() + 100;
needsRand = true;
} else {
needsRand = false;
}
canvas.drawText("" + r, 300, 100, myPaint);
physics();
invalidate();
}
回答1:
MyService.java
public class MyService extends Service implements SensorEventListener {
public void onCreate() {
super.onCreate();
sm = (SensorManager) getSystemService(SENSOR_SERVICE);
sm.unregisterListener(this);
sm.registerListener(this,sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),SensorManager.SENSOR_DELAY_FASTEST);
}
public void onDestroy() {
super.onDestroy();
sm.unregisterListener(this);
}
// Creates a new binder
@Override
public IBinder onBind(Intent intent) {
return new MyBinder<MyService>(this);
}
public void onSensorChanged(SensorEvent event) {
ax=event.values[0];
ay=event.values[1];
az=event.values[2];
for (Listener listener : listeners) listener.handleNewAccelValue(this);
}
public interface Listener {
// Actions to take when a new position has been added to the model
void handleNewAccelValue(MyService sender);
}
// List of all the ongoing listeners bound to the Model
private List<Listener> listeners = new ArrayList<Listener>();
// Binds a listener from the View to the Model
public void addListener(Listener listener) {
this.listeners.add(listener);
}
// Removes a listener from the View to the Model
public void removeListener(Listener listener) {
this.listeners.remove(listener);
}
YourActivity.java
public class YourActivity implements MyService.Listener{
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
// Binds to the created service
doBindService();
}
// Creating the controller and the model
private ServiceComputeFinal controller;
// Creates the connection with a MyService service
ServiceConnection connection = new ServiceConnection(){
public void onServiceConnected(ComponentName name, IBinder binder) {
controller = ((MyBinder<MyService>) binder).getService();
}
public void onServiceDisconnected(ComponentName name) {
controller = null;
}
};
// Binds to the created service
void doBindService(){
bindService(new Intent(this, MyService.class), connection, Context.BIND_AUTO_CREATE);
}
// And finally recover the accelerometer data that interest you
public void handleNewAccelValue(MyService sender){
DO_WHATEVER_YOU_WANT_WITH(controller.getAx());
}
I gave you all the tools to do what you want. Try to look at this code and understand what it does (it's not really complicated), a ServiceConnection allows the Activity to recover values from the Service and the Listener interface allows the Service to notify the Activity when new values are ready. Feel free to ask anything if needed.
回答2:
The method you use looks really strange to me. You actually pull accelerometer values in your drawing class. It's like, you create an instance of the accelerometer class, then take away his values right away (without waiting for the real accelerometer to actually retrieve values) then try to draw it. That is probably your problem anyway, you draw the starting accelerometer values and don't refresh them when they change. I don't know what's the rest of your code, but if you onDraw is called several time, you just create a new instance of your class and again the values you pull out from it didn't have time to be changed by the sensor readings.
You would better use a push method, implementing a listener interface in the accelerometer class so whenever a new value of acceleration is retrieved, the drawing class is notified and gets the new values, then draw them.
edit : I highly recommend you to use a faster delay for your accelerometer (Fastest will do it). Keep in mind the accelero is the less power-consuming of them all.
来源：https://stackoverflow.com/questions/10943351/accelerometer-not-changing-values