如何在没有用户互动的情况下发送短信？

实际上，以编程方式发送SMS时，您需要实现一个平台通道并用于SMSManager发送SMS。

例：

Android部分：

首先向添加适当的权限AndroidManifest.xml。

<uses-permission android:name="android.permission.SEND_SMS" />

然后在您的MainActivity.java：

package com.yourcompany.example;

import android.os.Bundle;
import android.telephony.SmsManager;
import android.util.Log;
import io.flutter.app.FlutterActivity;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugins.GeneratedPluginRegistrant;

public class MainActivity extends FlutterActivity {
  private static final String CHANNEL = "sendSms";

  private MethodChannel.Result callResult;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    GeneratedPluginRegistrant.registerWith(this);
    new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(
            new MethodChannel.MethodCallHandler() {
              @Override
              public void onMethodCall(MethodCall call, MethodChannel.Result result) {
                if(call.method.equals("send")){
                   String num = call.argument("phone");
                   String msg = call.argument("msg");
                   sendSMS(num,msg,result);
                }else{
                  result.notImplemented();
                }
              }
            });
  }

  private void sendSMS(String phoneNo, String msg,MethodChannel.Result result) {
      try {
          SmsManager smsManager = SmsManager.getDefault();
          smsManager.sendTextMessage(phoneNo, null, msg, null, null);
          result.success("SMS Sent");
      } catch (Exception ex) {
          ex.printStackTrace();
          result.error("Err","Sms Not Sent","");
      }
  }

}

飞镖代码：

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter/services.dart';

void main() {
  runApp(new MaterialApp(
    title: "Rotation Demo",
    home: new SendSms(),
  ));
}


class SendSms extends StatefulWidget {
  @override
  _SendSmsState createState() => new _SendSmsState();
}

class _SendSmsState extends State<SendSms> {
  static const platform = const MethodChannel('sendSms');

  Future<Null> sendSms()async {
    print("SendSMS");
    try {
      final String result = await platform.invokeMethod('send',<String,dynamic>{"phone":"+91XXXXXXXXXX","msg":"Hello! I'm sent programatically."}); //Replace a 'X' with 10 digit phone number
      print(result);
    } on PlatformException catch (e) {
      print(e.toString());
    }
  }

  @override
  Widget build(BuildContext context) {
    return new Material(
      child: new Container(
        alignment: Alignment.center,
        child: new FlatButton(onPressed: () => sendSms(), child: const Text("Send SMS")),
      ),
    );
  }
}

希望这对您有所帮助！

** 注意：

1.示例代码未显示如何在版本6.0及更高版本的android设备上处理权限。如果用于6.0实现正确的权限调用代码。

2.在双SIM卡手机的情况下，该示例也未实现选择SIM卡。如果在双SIM卡手机上未为短信设置默认SIM卡，则可能不会发送短信。