我正在编写一个应用程序，我必须将数据存储在加速度计值的文件中。我怎么做 ？我只需要创建一次文件并将数据附加到该文件中。这是申请流程：
Plz帮助..
编辑1：根据@iTech的代码，但它不附加数据。
import java.io.*;
import java.util.ArrayList;
import java.util.List;
import app.AccelLocData;
import com.google.android.gms.maps.*;
import com.google.android.gms.maps.GoogleMap.OnMapClickListener;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.Dialog;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
public class MapViewActivity extends Activity implements LocationListener,
SensorEventListener, OnClickListener {
GoogleMap googleMap;
private boolean started = false;
private ArrayList<AccelLocData> sensorData;
private SensorManager sensorManager;
private Button btnStart, btnStop;
private String provider;
File root, dir, sensorFile;
FileOutputStream fOut;
// ObjectOutputStream myOutWriter;
private Sensor mAccelerometer;
private FileWriter writer;
// private Button btnUpload;
@SuppressLint("NewApi")
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
root = android.os.Environment.getExternalStorageDirectory();
dir = new File(root.getAbsolutePath() + "/myapp");
dir.mkdirs();
File oldFile = new File(dir, "data.txt");
boolean deleted = oldFile.delete();
System.out.println("Delete status = " + deleted);
sensorFile = new File(dir, "data.txt");
sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
mAccelerometer = sensorManager
.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
btnStart = (Button) findViewById(R.id.btnStart);
btnStop = (Button) findViewById(R.id.btnStop);
btnStart.setOnClickListener(this);
btnStop.setOnClickListener(this);
btnStart.setEnabled(true);
btnStop.setEnabled(false);
int status = GooglePlayServicesUtil
.isGooglePlayServicesAvailable(getBaseContext());
if (status != ConnectionResult.SUCCESS) { // Google Play Services
// are
// not available
int requestCode = 10;
Dialog dialog = GooglePlayServicesUtil.getErrorDialog(status,
this, requestCode);
dialog.show();
} else { // Google Play Services are available
// Getting reference to the SupportMapFragment of
// activity_main.xml
// SupportMapFragment supportMapFragment = (MapFragment)
// getFragmentManager().findFragmentById(R.id.map);
// Getting GoogleMap object from the fragment
googleMap = ((MapFragment) getFragmentManager()
.findFragmentById(R.id.map)).getMap();
// googleMap = supportMapFragment.getMap();
// can use for overlay on the map
List<Double> latList = new ArrayList<Double>();
latList.add(45.7309593);
latList.add(46.34);
latList.add(47.34);
List<Double> lonList = new ArrayList<Double>();
lonList.add(-122.6365384);
lonList.add(-123.6365384);
lonList.add(-124.6365384);
for (int i = 0; i < 3; i++) {
// LatLng latLng = new LatLng(45.7309593, -122.6365384);
LatLng latLng = new LatLng(latList.get(i).doubleValue(),
lonList.get(i).doubleValue());
googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
googleMap
.addMarker(new MarkerOptions()
.position(latLng)
.title("My Spot")
.snippet("This is my spot!")
.icon(BitmapDescriptorFactory
.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
}
googleMap.setOnMapClickListener(new OnMapClickListener() {
@Override
public void onMapClick(LatLng latLng) {
// Creating a marker
MarkerOptions markerOptions = new MarkerOptions();
// Setting the position for the marker
markerOptions.position(latLng);
// Setting the title for the marker.
// This will be displayed on taping the marker
markerOptions.title(latLng.latitude + " : "
+ latLng.longitude);
// Clears the previously touched position
googleMap.clear();
// Animating to the touched position
googleMap.animateCamera(CameraUpdateFactory
.newLatLng(latLng));
// Placing a marker on the touched position
googleMap.addMarker(markerOptions);
}
});
// Enabling MyLocation Layer of Google Map
googleMap.setMyLocationEnabled(true);
LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, true);
Location location = locationManager
.getLastKnownLocation(provider);
if (location != null) {
onLocationChanged(location);
}
locationManager
.requestLocationUpdates(provider, 20000, 0, this);
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void onSensorChanged(SensorEvent event) {
if (started) {
double x = event.values[0];
double y = event.values[1];
double z = event.values[2];
long timestamp = System.currentTimeMillis();
LocationManager locManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
criteria.setPowerRequirement(Criteria.POWER_MEDIUM);
criteria.setAccuracy(Criteria.ACCURACY_FINE);
provider = locManager.getBestProvider(criteria, true);
Location location = locManager.getLastKnownLocation(provider);
double latitude = 0;
double longitude = 0;
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
AccelLocData data = new AccelLocData(timestamp, x, y, z, latitude,
longitude);
System.out.println("data x:" + data.getX());
try {
writer.write(data.toString());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
@Override
public void onLocationChanged(Location location) {
TextView tvLocation = (TextView) findViewById(R.id.tv_location);
// Getting latitude of the current location
double latitude = location.getLatitude();
// Getting longitude of the current location
double longitude = location.getLongitude();
// Creating a LatLng object for the current location
LatLng latLng = new LatLng(latitude, longitude);
// Showing the current location in Google Map
googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
// Zoom in the Google Map
googleMap.animateCamera(CameraUpdateFactory.zoomTo(15));
// System.out.println("Latitude:" + latitude + ", Longitude:" +
// longitude);
// Setting latitude and longitude in the TextView tv_location
// tvLocation.setText("Latitude:" + latitude + ", Longitude:" +
// longitude);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnStart:
btnStart.setEnabled(false);
btnStop.setEnabled(true);
System.out.println("cam on click of start");
started = true;
sensorManager.registerListener(this, mAccelerometer,
SensorManager.SENSOR_DELAY_FASTEST);
break;
case R.id.btnStop:
try {
btnStart.setEnabled(true);
btnStop.setEnabled(false);
// btnUpload.setEnabled(true);
started = false;
sensorManager.unregisterListener(this);
/*
* if(writer != null) { try { writer.close(); } catch
* (IOException e) { // TODO Auto-generated catch block
* e.printStackTrace(); } }
*/} catch (Exception e) {
e.printStackTrace();
}
break;
default:
break;
}
}
protected void onPause() {
super.onPause();
if (writer != null) {
try {
writer.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
protected void onResume() {
super.onResume();
try {
System.out.println("called onresume");
writer = new FileWriter(sensorFile, true);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void onProviderDisabled(String arg0) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
@Override
public void onAccuracyChanged(Sensor arg0, int arg1) {
// TODO Auto-generated method stub
}
}
答案 0 :(得分：3)
以下是您开始使用的示例代码。
您可以检查Android示例以了解如何从传感器读取数据，然后将其写入文件。
要运行此代码，您需要添加两个按钮，并将onClick设置为onStartClick和onStopClick。您也可以指定SD卡上的输出文件路径。
public class Main extends Activity implements SensorEventListener {
private SensorManager mSensorManager;
private Sensor mAccelerometer;
private FileWriter writer;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activiy_main);
mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
}
public void onStartClick(View view) {
mSensorManager.registerListener(this, mAccelerometer, SensorManager.SENSOR_DELAY_NORMAL);
}
public void onStopClick(View view) {
mSensorManager.unregisterListener(this);
}
protected void onResume() {
super.onResume();
writer = new FileWriter("myfile.txt",true);
}
protected void onPause() {
super.onPause();
if(writer != null) {
writer.close();
}
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
@Override
public void onSensorChanged(SensorEvent event) {
float x = event.values[0];
float y = event.values[1];
float z = event.values[2];
writer.write(x+","+y+","+z+"\n");
}
}