一、MainActivity和activity_main

import androidx.appcompat.app.AppCompatActivity;import android.content.ContentResolver;
import android.content.Intent;
import android.content.ServiceConnection;
import android.net.Uri;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;public class MainActivity extends AppCompatActivity {private Button start;private Button stop;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);start = findViewById(R.id.start);stop = findViewById(R.id.stop);//收取Intent intent = new Intent(MainActivity.this, MessageService.class);start.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {startService(intent);Toast.makeText(MainActivity.this, "开始监听", Toast.LENGTH_LONG).show();}});stop.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {stopService(intent);Toast.makeText(MainActivity.this, "关闭监听", Toast.LENGTH_LONG).show();}});//TODO 下面这一行功能没用，可以删掉getApplicationContext().getContentResolver().registerContentObserver(Uri.parse("content://sms/"),true, new SmsObserver(this, new Handler()));//为content://sms 的数据改变注册监听器
//        ContentResolver contentResolver = getContentResolver();
//        Uri uri= Uri.parse("content://sms/");
//        contentResolver.registerContentObserver(uri,true,new SMSActivity.SmsObsever(new Handler()));}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".MainActivity"><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_centerHorizontal="true"android:layout_centerVertical="true"android:text="Hello World!" /><RelativeLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"><Buttonandroid:id="@+id/start"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="开启监听" /><Buttonandroid:id="@+id/stop"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_alignParentBottom="true"android:text="关闭监听" /></RelativeLayout><RelativeLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"></RelativeLayout></RelativeLayout>

二、创建service和util类

MessageService类

import android.app.Service;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.IBinder;import java.security.Provider;public class MessageService extends Service {private MessageReciever mReceiver;@Overridepublic IBinder onBind(Intent arg0) {return null;}@Overridepublic void onCreate() {mReceiver = new MessageReciever();IntentFilter filter = new IntentFilter("android.provider.Telephony.SMS_RECEIVED");registerReceiver(mReceiver, filter);}@Overridepublic void onDestroy() {if(null != mReceiver){unregisterReceiver(mReceiver);mReceiver = null;}}@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {return super.onStartCommand(intent, flags, startId);}@Overridepublic boolean onUnbind(Intent intent) {return super.onUnbind(intent);}
}

MessageReciever类

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.SmsMessage;
import android.telephony.TelephonyManager;
import android.widget.Toast;import static android.telephony.TelephonyManager.PHONE_TYPE_CDMA;public class MessageReciever extends BroadcastReceiver {private static final String SMS_RECEIVER_ACTION = "android.provider.Telephony.SMS_RECEIVED";@Overridepublic void onReceive(Context context, Intent intent) {StringBuilder sBuilder = new StringBuilder();String format = intent.getStringExtra("format");if(SMS_RECEIVER_ACTION.equals(intent.getAction())){Bundle bundle = intent.getExtras();if(null != bundle){Object[] pdus = (Object[])bundle.get("pdus");assert pdus != null;SmsMessage[] messages = new SmsMessage[pdus.length];for(int i = 0; i < messages.length; ++i){messages[i] = SmsMessage.createFromPdu((byte[])pdus[i],format);}for(SmsMessage msg : messages){sBuilder.append("来自：").append(msg.getDisplayOriginatingAddress()).append("\n").append("短信内容：");sBuilder.append(msg.getDisplayMessageBody()).append("\n");}}}Toast.makeText(context, "您收到了一条短信!!\n" + sBuilder.toString(), Toast.LENGTH_LONG).show();}}

三、配置manifest和开启权限

这一段内容必须加

    <!-- 接收消息 --><uses-permission android:name="android.permission.RECEIVE_SMS"/><!--  发送消息--><uses-permission android:name="android.permission.SEND_SMS"/><!--  阅读消息--><uses-permission android:name="android.permission.READ_SMS"/><!--  写入消息--><uses-permission android:name="android.permission.WRITE_SMS" />

这一段内容如果要使用广播就加service

        <!-- Service --><service android:name=".service.MessageService"android:label="@string/app_name"android:exported="true"><intent-filter><action android:name="org.anymobile.test.service.IMICHAT" /><category android:name="android.intent.category.DEFAULT" /></intent-filter></service><!-- Receiver -->
<!--        <receiver android:name=".util.MessageReciever"-->
<!--            android:exported="true">-->
<!--            <intent-filter>-->
<!--                <action android:name="android.provider.Telephony.SMS_RECEIVED" />-->
<!--            </intent-filter>-->
<!--        </receiver>-->

app运行后，要长按应用进入App Info修改权限