动态注册广播 监听网络变化

观看书籍,还望指正

1, 创建intentFilter实例 并添加action android.net.conn.CONNECTIVITY_CHANGE

2, 定义一个新的内部类networkChangeReceiver继承BroadcasetReceiver 重写onReceiver()方法

3, newworkChangeReceiver实例 调用registerReceiver()注册

4,重载onDestroy()方法

代码如下:

优化前

MainActivity.java

import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.widget.Toast;public class MainActivity extends AppCompatActivity {    private IntentFilter intentFilter;    private NetworkChangeReceiver networkChangeReceiver;    @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);    }    @Override    protected void onDestroy(){        super.onDestroy();        unregisterReceiver(networkChangeReceiver);    }     class NetworkChangeReceiver extends BroadcastReceiver{        @Override        public void onReceive(Context context, Intent intent){            Toast.makeText(context,"network changes",Toast.LENGTH_SHORT).show();        }    }}

优化后

MainActivity.java

import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.net.ConnectivityManager;import android.net.NetworkInfo;import android.support.v4.graphics.drawable.TintAwareDrawable;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.widget.Toast;public class MainActivity extends AppCompatActivity {    private IntentFilter intentFilter;    private NetworkChangeReceiver networkChangeReceiver;    @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);    }    @Override    protected void onDestroy(){        super.onDestroy();        unregisterReceiver(networkChangeReceiver);    }     class NetworkChangeReceiver extends BroadcastReceiver{        @Override        public void onReceive(Context context, Intent intent){//            Toast.makeText(context,"network changes",Toast.LENGTH_SHORT).show();            ConnectivityManager connectionManager=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);            //通过getSystemService()方法得到connectionManager的实例            NetworkInfo networkInfo=connectionManager.getActiveNetworkInfo();            //通过getActiveNetworkInfo()方法得到networkInfo的实例            if(networkInfo!=null &&networkInfo.isAvailable()){                Toast.makeText(context,"network is available",Toast.LENGTH_SHORT).show();            }else            {                Toast.makeText(context,"network is unavailable",Toast.LENGTH_SHORT).show();            }        }    }}