安卓學習之廣播的動態監聽

Android內置了很多廣播，例如手機開機，電量充滿，關機等各種廣播。

1.聲明廣播的過濾器

private IntentFilter intentFilter;

2.聲明廣播接受類並且重寫onReceive方法

private NetworkChangeReceiver networkChangeReceiver;//自定義接受類
 class NetworkChangeReceiver extends BroadcastReceiver
    {
        @Override
        public void onReceive(Context context, Intent intent) {
           ConnectivityManager connectivityManager=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
           NetworkInfo networkInfo=connectivityManager.getActiveNetworkInfo();
           if(networkInfo!=null&&networkInfo.isAvailable())
           {
               Toast.makeText(getApplicationContext(),"網絡連接成功",Toast.LENGTH_LONG).show();;
           }
           else
           {
               Toast.makeText(getApplicationContext(),"網絡連接失敗",Toast.LENGTH_LONG).show();;
           }
            Toast.makeText(getApplicationContext(),"NETWORD",Toast.LENGTH_LONG).show();;
        }
    }

3.註冊監聽事件

 intentFilter=new IntentFilter();
        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
        networkChangeReceiver=new NetworkChangeReceiver();
        registerReceiver(networkChangeReceiver,intentFilter);//註冊監聽事件

4.結束註冊監聽事件

  unregisterReceiver(networkChangeReceiver);

全部代碼如下

package com.example.broadcasttext;

import androidx.appcompat.app.AppCompatActivity;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.net.Network;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

   private IntentFilter intentFilter;
    private NetworkChangeReceiver networkChangeReceiver;//自定義接受類
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        intentFilter=new IntentFilter();
        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
        networkChangeReceiver=new NetworkChangeReceiver();
        registerReceiver(networkChangeReceiver,intentFilter);//註冊監聽事件
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(networkChangeReceiver);
    }

    class NetworkChangeReceiver extends BroadcastReceiver
    {
        @Override
        public void onReceive(Context context, Intent intent) {
            //聲明網絡管理類
           ConnectivityManager connectivityManager=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
           //獲得網絡信息類
           NetworkInfo networkInfo=connectivityManager.getActiveNetworkInfo();
           if(networkInfo!=null&&networkInfo.isAvailable())
           {
               Toast.makeText(getApplicationContext(),"網絡連接成功",Toast.LENGTH_LONG).show();;
           }
           else
           {
               Toast.makeText(getApplicationContext(),"網絡連接失敗",Toast.LENGTH_LONG).show();;
           }
            Toast.makeText(getApplicationContext(),"NETWORD",Toast.LENGTH_LONG).show();;
        }
    }
}