我正在为盲人开发一个 Android 导航应用程序。所以自然不用在屏幕上显示地图。我的代码现在通过构建一个 url 然后解析 html 文档来获取路径。我想让这个活，即我想在他/她偏离道路或走错方向时处理这个案子，我希望我的应用程序提醒他。
使用谷歌地图功能可以做到这一点吗？如果可能，请提供有关该功能的详细信息，或者如果不存在此类功能，那么是否可以使用现有功能并以某种方式使用它来帮助解决问题。
这是我现在的代码：
public class GPSTracking extends Activity implements
TextToSpeech.OnInitListener
{
protected static final int RESULT_SPEECH_start = 1;
protected static final int RESULT_SPEECH_end = 2;
protected static final int RESTART_ALL = 3;
//total distance travelled till last turn
Float totalDistance;
//distance to be travelled from present point to the next point
Float obtainedDistance;
//upper button
Button btnShowLocation;
//bottom button
Button btnShowLocationNo;
//to narate what user should do.
TextToSpeech tts;
//used to get name of current location
Geocoder geocoder;
//used to find positioning feature
GPS gps;
//start and position of the journey
String startPosition=null, endPosition=null;
//strings containing the path.
String[] string = null;
//vibrate the mobile
Vibrator viberator;
//indexing the present value of string which contains the path
int i = 0;
//to maintain proper order of events
int steps=0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//button on top
btnShowLocation = (Button) findViewById(R.id.trueButton);
//button on the lower side
btnShowLocationNo = (Button) findViewById(R.id.falseButton);
//initialising the text to speech
tts = new TextToSpeech(this, this);
//initialising the vibrator.
viberator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
//to know what the current location
btnShowLocation.setOnClickListener(new View.OnClickListener() {
//to avoid start of multiple threads
boolean mytaskStarted=false;
String str=null;
@Override
public void onClick(View v) {
if(steps==0){
//to make sure values are reset
totalDistance=(float)0;
obtainedDistance=(float)0;
mytaskStarted=false;
string=null;
str=null;
i=0;
//only ask for initial position if not set
if(startPosition == null){
speakOut("Please enter the start position");
//takes the input using speech to text
intentGenerator(RESULT_SPEECH_start);
}
else{
//to enter the destination
speakOut("press the button again");
steps=1;
}
}
else if(steps==1){
//to enter the destination
speakOut("Please enter the destination");
intentGenerator(RESULT_SPEECH_end);
}
else if(steps==2){
//for a impatient user
speakOut("please wait");
//to avoid start of many asynchronous task
if(!mytaskStarted){
mytaskStarted=true;
//asynchronous task to find the path to be followed
new GetPath().execute();
}
}
else if(steps==3){
if (string != null && i < string.length) {
if(gps!=null && gps.isGpsEnabled()){
speakOut(i + 1 + " " + string[i]);
if(i>0 && i<string.length-1 && (string[i]+" ").lastIndexOf(" m ")>-1){
str=(string[i]+" ").substring(0,(string[i]+" ").lastIndexOf(" m ")+3);
obtainedDistance=Float.parseFloat(str.substring(1+str.substring(0,str.substring(0,str.lastIndexOf(" ")).lastIndexOf(" ")).lastIndexOf(" "),str.substring(0,str.lastIndexOf(" ")).lastIndexOf(" ")));
//increment only when present distance greater than distance in present string so that one will know when to turn.
if(((totalDistance+obtainedDistance)-gps.getApprximateDistance())<10)
{
i++;
totalDistance=totalDistance+obtainedDistance;
}
}
else if(i>0 && i<string.length-1 && (string[i]+" ").lastIndexOf(" km ")>-1){
str=(string[i]+" ").substring(0,(string[i]+" ").lastIndexOf(" km ")+4);
obtainedDistance=Float.parseFloat(str.substring(1+str.substring(0,str.substring(0,str.lastIndexOf(" ")).lastIndexOf(" ")).lastIndexOf(" "),str.substring(0,str.lastIndexOf(" ")).lastIndexOf(" ")));
obtainedDistance*=1000;
//increment only when present distance greater than distance in present string so that one will know when to turn.
if(((totalDistance+obtainedDistance)-gps.getApprximateDistance())<10)
{
i++;
totalDistance=totalDistance+obtainedDistance;
}
}
else if(i==0 ){
i++;
}
}
else if(gps!=null){
gps.resetDistance();
gps.stopUsingGPS();
//if gps not working.
speakOut(i + 1 + " " + string[i]);
i++;
}
else{
speakOut(i + 1 + " " + string[i]);
i++;
}
} else if (string != null && i >= string.length) {
i = 0;
}
}
}
});
//to get present location
btnShowLocation.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
if(gps==null){
gps = new GPS(AndroidGPSTrackingActivity.this);
}
if (gps.canGetLocation()) {
double longitude = gps.getLongitude();
double latitude = gps.getLatitude();
Geocoder geocoder = new Geocoder(getApplicationContext(), Locale.getDefault());
try {
//obtain the address of present location
List<Address> listAddresses = geocoder.getFromLocation(latitude, longitude, 1);
if(null!=listAddresses&&listAddresses.size()>0){
if (listAddresses.size() > 0) {
StringBuilder result = new StringBuilder();
for(int i = 0; i < listAddresses.size(); i++){
Address address = listAddresses.get(i);
int maxIndex = address.getMaxAddressLineIndex();
for (int x = 0; x <= maxIndex; x++ ){
if(address.getAddressLine(x)!=null){
result.append(address.getAddressLine(x));
result.append(",");
}
}
if(address.getLocality()!=null){
result.append(address.getLocality());
result.append("\n\n");
}
}
//if position accurate
if(gps.isGpsEnabled()){
speakOut(result.toString()+" is Your current location");
startPosition=result.toString();
Toast.makeText(
getApplicationContext(),startPosition,
Toast.LENGTH_LONG).show();
} else if(gps.isNetworkEnabled()){
speakOut(result.toString()+" is Your current approximate location. You have to give input of your present location on your own.");
Toast.makeText(
getApplicationContext(),result.toString(),
Toast.LENGTH_LONG).show();
}
}
}
} catch (IOException e) {
e.printStackTrace();
}
} else {
gps.showSettingsAlert();
startPosition=null;
speakOut(" please turn on gps");
}
return false;
}
});
//to know what the previous direction string
btnShowLocationNo.setOnClickListener(new View.OnClickListener() {
int j=0;
@Override
public void onClick(View arg0) {
if(string!=null && j<string.length){
speakOut(j + 1 + " " + string[j]);
j++;
}
else if(string!=null && j>=string.length){
j=0;
}
}
});
//to reset all values for fresh start
btnShowLocationNo.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
// TODO Auto-generated method stub
speakOut("Values reset");
steps=0;
string=null;
i=0;
startPosition=null;
gps.stopUsingGPS();
gps=null;
endPosition=null;
return false;
}
});
}
//function to handle he text obtained from speech to text.
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch (requestCode) {
//set the start
case RESULT_SPEECH_start:
if (resultCode == RESULT_OK && null != data) {
ArrayList<String> text = data
.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
Toast.makeText(getApplicationContext(), text.get(0),
Toast.LENGTH_SHORT).show();
startPosition = text.get(0);
steps=1;
//speakOut("please press button again");
}
else{
steps=0;
}
break;
//to set the end
case RESULT_SPEECH_end:
if (resultCode == RESULT_OK && null != data) {
ArrayList<String> text = data
.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
Toast.makeText(getApplicationContext(), text.get(0),
Toast.LENGTH_SHORT).show();
endPosition = text.get(0);
steps=2;
}
else{
steps=1;
}
break;
}
}
//function to generate intent to take speech input
public void intentGenerator(int code) {
Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, "en-US");
try {
startActivityForResult(intent, code);
} catch (ActivityNotFoundException a) {
Toast.makeText(getApplicationContext(),
"Opps! Your device doesn't support Speech to Text",
Toast.LENGTH_SHORT).show();
speakOut("Opps! Your device doesn't support Speech to Text");
}
}
//mobile gives instruction.
private void speakOut(String text) {
tts.speak(text, TextToSpeech.QUEUE_FLUSH, null);
while (tts.isSpeaking()) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
//asynchronous task to get the path. THIS IS USED TO AVOID OVERLOAD THE MAIN THRED AND AVOID FORCE CLOSE OF THE APPLICATION
private class GetPath extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... params) {
try {
string=null;
String html="";
//forming url
URL net = new URL(("http://maps.google.com/maps?saddr="+startPosition+" &daddr= "+endPosition).replaceAll(" ","%20"));
URLConnection netConnection = null;
netConnection = net.openConnection();
//to take the input from google maps
BufferedReader in = null;
in = new BufferedReader(new InputStreamReader(netConnection.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null) {
html+=inputLine;
}
//jsoup parser to parse the document obtained from google maps
Document doc = Jsoup.parse(html);
//obtain necessary part of the document
Elements el = doc.getElementsByClass("dir-mrgnr");
//to remove html tags
String str = el.text();
str = str.replaceAll("[0-9]+[.] ", "\n");
string = str.split("\n");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
@Override
protected void onProgressUpdate(Void... values) {
// TODO Auto-generated method stub
super.onProgressUpdate(values);
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
//so that on press of button again mobile can read the directions to users
steps=3;
}
}
@Override
public void onDestroy() {
//shutdown
if (tts != null) {
tts.stop();
tts.shutdown();
}
super.onDestroy();
}
@Override
protected void onStart() {
gps = new GPS(AndroidGPSTrackingActivity.this);
super.onStart();
}
@Override
protected void onStop() {
if (tts != null) {
tts.stop();
tts.shutdown();
}
if(gps!=null){
gps.stopUsingGPS();
}
super.onStop();
}
@Override
public void onInit(int status) {
//initialising the text to speech
if (status == TextToSpeech.SUCCESS) {
int result = tts.setLanguage(Locale.US);
if (result == TextToSpeech.LANG_MISSING_DATA
|| result == TextToSpeech.LANG_NOT_SUPPORTED) {
Log.e("TTS", "Language is not supported");
} else {
btnShowLocation.setEnabled(true);
}
} else {
Log.e("TTS", "Initilization Failed");
}
}
}