有没有办法检测Android上的传出呼叫是以编程方式解答还是拒绝？

Question

我正在开发一项测试，以检查Android手机是否能够拨打和接听电话。我刚刚编写了以下代码来检查并记录呼叫在接收来电和拨打电话时所处的不同状态：

import java.util.Date;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.telephony.TelephonyManager;

public 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.
    if (intent.getAction().equals("android.intent.action.NEW_OUTGOING_CALL")) {
        savedNumber = intent.getExtras().getString("android.intent.extra.PHONE_NUMBER");
    }
    else{
        String stateStr = intent.getExtras().getString(TelephonyManager.EXTRA_STATE);
        String number = intent.getExtras().getString(TelephonyManager.EXTRA_INCOMING_NUMBER);
        int state = 0;
        if(stateStr.equals(TelephonyManager.EXTRA_STATE_IDLE)){
            state = TelephonyManager.CALL_STATE_IDLE;
        }
        else 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);
    }
}

protected abstract void onIncomingCallReceived(Context ctx, String number, Date start);
protected abstract void onIncomingCallAnswered(Context ctx, String number, Date start);
protected abstract void onIncomingCallEnded(Context ctx, String number, Date start, Date end);

protected abstract void onOutgoingCallStarted(Context ctx, String number, Date start);
protected abstract void onOutgoingCallEnded(Context ctx, String number, Date start, Date end);

protected abstract 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;
            onIncomingCallReceived(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);
            }
            else
            {
                isIncoming = true;
                callStartTime = new Date();
                onIncomingCallAnswered(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;
}
}

上面的代码工作正常，但现在的问题是我没有在android中找到任何API，这可以告诉我是否已选择或拒绝拨出电话。我没有找到任何可以通知我的api。有没有人有解决方法怎么做？