Android - 如何创建 PhoneStateListener

Question

我有一个功能可以发起外拨电话。我需要设置监听器以了解通话状态（响铃、挂断等）。我无法弄清楚如何做到这一点，并且没有找到说明如何做到这一点的教程。这是拨打电话的设置：

PhoneCall.kt

class PhoneCall : AppCompatActivity() {
    private fun placeCall() {
        if(ActivityCompat.checkSelfPermission(this, android.Manifest.permission.CALL_PHONE) == PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permision.READ_PHONE_STATE) == PackageManager.PERMISSION_GRANTED) {
            val telephonyManager = getSystemService(Context.TELEPHONY_SERVICE) as TelephonyManager
            telephonyManager.listen(CallListener, PhoneStateListener.LISTEN_CALL_STATE) //Not sure how to set up CallListener here?
            val callIntent = Intent(Intent.ACTION_CALL, Uri.parse(phoneNumber))
            startActivity(callIntent)
        }
    }
}

我相信从CallListener 我可以创建一个when() 来查找当前状态。但是我不确定如何创建 CallListener 并且这似乎不是一个真正的听众？ CallListener 是否需要是一个新的类、对象或其他东西？我想我可能需要一个广播接收器？我不知道正确的处理方法。

Answer 1

我有一个项目，我做了类似的事情，我创建了两个类，一个是 PhoneCallListener 和 PhoneCallReceiver。我已经删除了一些用于我需要的代码，但是如果你实现了这两个类，你应该没问题。我不是专家，但希望对您有所帮助。

jsonObject 只是作为一个例子来展示“做某事”。我还应该提一下，我不了解 Kotlin，但有人告诉我 Android Studio 可以将 Java 转换为 Kotlin，所以它可能会有所帮助，希望有经验的人知道 Kotlin 的使用方法。

PhoneCallListener.java

    public class PhoneCallListener extends PhoneCallReceiver {

    @Override
    protected void onIncomingCallStarted(Context c, String number, Date start) {
            JSONObject jsonObject = new JSONObject();
            try {
                jsonObject.put("Timestamp", App.getUTCTimestamp());
                jsonObject.put("Direction", "incoming");
                jsonObject.put("Number", number);
            } catch (JSONException e) {
                e.printStackTrace();
            }
    }

    @Override
    protected void onOutgoingCallStarted(Context c, String number, Date start) {
            JSONObject jsonObject = new JSONObject();
            try {
                jsonObject.put("Timestamp", App.getUTCTimestamp());
                jsonObject.put("Direction", "outgoing");
                jsonObject.put("Number", number);
            } catch (JSONException e) {
                e.printStackTrace();
            }
    }

    @Override
    protected void onIncomingCallEnded(Context c, String number, Date start, Date end) 
            JSONObject jsonObject = new JSONObject();
            try {
                jsonObject.put("Timestamp", App.getUTCTimestamp());
                jsonObject.put("Direction", "incoming call ended");
                jsonObject.put("Number", number);
            } catch (JSONException e) {
                e.printStackTrace();
            });
    }

    @Override
    protected void onOutgoingCallEnded(Context c, String number, Date start, Date end) {
            JSONObject jsonObject = new JSONObject();
            try {
                jsonObject.put("Timestamp", App.getUTCTimestamp());
                jsonObject.put("Direction", "outgoing call ended");
                jsonObject.put("Number", number);
            } catch (JSONException e) {
                e.printStackTrace();
            }
    }

    @Override
    protected void onMissedCall(Context c, String number, Date start) {

            JSONObject jsonObject = new JSONObject();
            try {
                jsonObject.put("Timestamp", App.getUTCTimestamp());
                jsonObject.put("Direction", "missed");
                jsonObject.put("Number", number);
            } catch (JSONException e) {
                e.printStackTrace();
            }
    }
}

PhoneCallReceiver.java

abstract class PhoneCallReceiver extends BroadcastReceiver {

    //The receiver will be recreated whenever android feels like it.  We need a static variable to remember data between instantiations

    private static int lastState = TelephonyManager.CALL_STATE_IDLE;
    private static Date callStartTime;
    private static boolean isIncoming;
    private static String savedNumber;  //because the passed incoming is only valid in ringing


    @Override
    public void onReceive(Context context, Intent intent) {

        //We listen to two intents.  The new outgoing call only tells us of an outgoing call.  We use it to get the number.
        try {
            if (Objects.equals(intent.getAction(), "android.intent.action.NEW_OUTGOING_CALL")) {
                savedNumber = Objects.requireNonNull(intent.getExtras()).getString("android.intent.extra.PHONE_NUMBER");
            } else {
                String stateStr = Objects.requireNonNull(intent.getExtras()).getString(TelephonyManager.EXTRA_STATE);
                String number = intent.getExtras().getString(TelephonyManager.EXTRA_INCOMING_NUMBER);
                if (number == null) {
                    number = "00000000000"; // Caller Withheld.
                }

                int state = 0;
                assert stateStr != null;
                if (!stateStr.equals(TelephonyManager.EXTRA_STATE_IDLE)) {
                    if (stateStr.equals(TelephonyManager.EXTRA_STATE_OFFHOOK)) {
                        state = TelephonyManager.CALL_STATE_OFFHOOK;
                    } else if (stateStr.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
                        state = TelephonyManager.CALL_STATE_RINGING;
                    }
                }
                onCallStateChanged(context, state, number);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //Derived classes should override these to respond to specific events of interest
    protected void onIncomingCallStarted(Context ctx, String number, Date start) {
    }

    protected void onOutgoingCallStarted(Context ctx, String number, Date start) {
    }

    protected void onIncomingCallEnded(Context ctx, String number, Date start, Date end) {
    }

    protected void onOutgoingCallEnded(Context ctx, String number, Date start, Date end) {
    }

    protected void onMissedCall(Context ctx, String number, Date start) {
    }

    //Deals with actual events

    //Incoming call-  goes from IDLE to RINGING when it rings, to OFFHOOK when it's answered, to IDLE when its hung up
    //Outgoing call-  goes from IDLE to OFFHOOK when it dials out, to IDLE when hung up
    public void onCallStateChanged(Context context, int state, String number) {
        if (lastState == state) {
            //No change, debounce extras
            return;
        }
        switch (state) {
            case TelephonyManager.CALL_STATE_RINGING:
                isIncoming = true;
                callStartTime = new Date();
                savedNumber = number;
                onIncomingCallStarted(context, number, callStartTime);
                break;
            case TelephonyManager.CALL_STATE_OFFHOOK:
                //Transition of ringing->offhook are pickups of incoming calls.  Nothing done on them
                if (lastState != TelephonyManager.CALL_STATE_RINGING) {
                    isIncoming = false;
                    callStartTime = new Date();
                    onOutgoingCallStarted(context, savedNumber, callStartTime);
                }
                break;
            case TelephonyManager.CALL_STATE_IDLE:
                //Went to idle-  this is the end of a call.  What type depends on previous state(s)
                if (lastState == TelephonyManager.CALL_STATE_RINGING) {
                    //Ring but no pickup-  a miss
                    onMissedCall(context, savedNumber, callStartTime);
                } else if (isIncoming) {
                    onIncomingCallEnded(context, savedNumber, callStartTime, new Date());
                } else {
                    onOutgoingCallEnded(context, savedNumber, callStartTime, new Date());
                }
                break;
        }
        lastState = state;
    }
}