监听电话状态

监听手机的通话状态，是空闲还是正在通话中：
public class PhoneStateListenerActivity extends Activity {

private TextView mTextView;


protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.phone_state_listener);

Log.i("Lowry","==============activity on create");
mTextView = (TextView) findViewById(R.id.phont_state_textView);

ExPhoneCallListener exp = new ExPhoneCallListener();

TelephonyManager tpm = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);

tpm.listen(exp, PhoneStateListener.LISTEN_CALL_STATE);

Log.i("Lowry","==============activity on create2");
}


public class ExPhoneCallListener extends PhoneStateListener {

@Override
public void onCallStateChanged(int state, String incomingNumber) {
Log.i("Lowry","==============Call stata changed----"+state+"-----"+incomingNumber);
switch (state) {
case TelephonyManager.CALL_STATE_IDLE:

mTextView.setText("空闲");
break;
case TelephonyManager.CALL_STATE_OFFHOOK:

mTextView.setText("接起电话");
break;
case TelephonyManager.CALL_STATE_RINGING:
getContactPeople(incomingNumber);
break;
default:
break;
}

super.onCallStateChanged(state, incomingNumber);


}


}


private void getContactPeople(String incomingNumber){
mTextView.setTextColor(R.drawable.white);
ContentResolver contentResolver = getContentResolver();
Cursor cursor = null;
String[] projection = new String[]{Contacts.People._ID,Contacts.People.NAME,Contacts.People.NUMBER};

cursor = contentResolver.query(Contacts.People.CONTENT_URI,
projection, Contacts.People.NUMBER+"=?", new String[]{incomingNumber},
Contacts.People.DEFAULT_SORT_ORDER);

Log.i("Lowry", "++++++++++++++++++++"+cursor.getCount());

if(cursor.getCount()==0){
mTextView.setText("Unknown Number:"+incomingNumber);

}
else if(cursor.getCount()>0){
cursor.moveToFirst();
String name = cursor.getString(1);
mTextView.setText(name+"====="+incomingNumber);
}

}
}

通过setSystemService()取得TelePhonyManager对象，再向TelephonyManager对象注册PhoneCallListener，注册时，传入PhoneCallListener类以及要倾听的事件名称，本应用所聆听的是电话状态，所以聆听事件要带入PhoneStateListener.LISTEN_CALL_STATE
得到电话状态并在mTextView中做显示，可以直观的看到当前的电话状态。