(原创)用Receiver和SystemService监听网络状态,注册Receiver的两种方式

android中网络编程不可避免地要监听网络状态,wifi或者3G以及以太网,并根据当前状态做出相应决策.

在MyReceiver类中的onReceive方法中获得系统服务

ConnectivityManager manager = (ConnectivityManager) context
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo wifiInfo = manager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
        NetworkInfo mobInfo = manager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);

        if(wifiInfo.isConnected){
            Toast.makeText(context, "wifi isConnected", Toast.LENGTH_SHORT).show();
            return;
        }else if(mobInfo.isConnected()){
            Toast.makeText(context, "mob isConnected", Toast.LENGTH_SHORT).show();
            return;
        }else{
            Toast.makeText(context, "none is Connected", Toast.LENGTH_SHORT).show();
            return;
        }

静态注册方法:

<receiver android:name=".MyReceiver">
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
            </intent-filter>
</receiver>  

或者动态注册方法(MainActivity中):

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

        IntentFilter filter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
        myReceiver = new myWifiReceiver();
        registerReceiver(myReceiver, filter);
    }

    @Override
    protected void onDestroy() {
        unregisterReceiver(myReceiver);
        super.onDestroy();
    }

权限:

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

这里要注意两点:

1.动态注册并且onDestroy()时解除注册的话,退出后就不接受广播了.

但是再次打开应用时会执行onReceive()方法.

2.较高api版本中要求打开过应用广播接收者才会生效.