Android笔记（六十）Android总结：四大组件——BroadcastReceiver篇

       BroadcastReceiver是Android体系的四大组件之一，本质上是一种全局的监听器，用于监听系统全局的广播消息，正式因为其本质为全局监听，因此可以非常方便的实现系统中不同组件之间的通信。也方便我们自己的app针对系统开机、电量低等广播做出相应反映。同时我们也可以自己发送广播，来实现不同组件之间的通信

       系统接收短信广播，然后弹出Toast：

package cn.lixyz.broadcastreceiver;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

public class MainActivity extends Activity {

    private IntentFilter filter;
    private SMSReceiver sms;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        filter = new IntentFilter("android.provider.Telephony.SMS_RECEIVED");
        sms = new SMSReceiver();
        registerReceiver(sms, filter);

    }

    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        unregisterReceiver(sms);
    }

    class SMSReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            Toast.makeText(context, "有短信", Toast.LENGTH_SHORT).show();
            Log.d("TTTT", "~~~~~~~");
        }
    }
}

MainActivity.java