Android---动态注册监听网路变化的广播

package com.mycompany.broadcasttest;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;/** * 动态注册监听网路变化 */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);        /**         * 1、首先创建了一个IntentFilter实例，并给它添加了一个值为android.net.conn.CONNECTIVITY_CHANGE的action         * 2、当网络发生变化时，系统发出的就是"android.net.conn.CONNECTIVITY_CHANGE"的广播         * 3、即我们的广播接收器里面想要监听什么广播，就在这里添加相应的action         * 4、接着创建一个NetworkChangeReceiver的实例，然后调用registerReceiver方法进行注册，将networkChangeReceiver、networkChangeReceiver都传入         * 5、这样NetworkChangeReceiver就会收到值为"android.net.conn.CONNECTIVITY_CHANGE"的广播         * 6、重要：动态注册的广播接收器一定要取消注册才行，调用unregisterReceiver()方法进行取消         */        intentFilter = new IntentFilter();        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");        networkChangeReceiver = new NetworkChangeReceiver();        registerReceiver(networkChangeReceiver, intentFilter);    }    @Override    protected void onDestroy() {        super.onDestroy();        unregisterReceiver(networkChangeReceiver);    }    /**     * 自定义了一个继承于BroadcastReceiver的内部类，并重写OnReceive()方法     * 这样每当网络状态发生变化是，OnReceive()都会得到执行     */    class NetworkChangeReceiver extends BroadcastReceiver {        @Override        public void onReceive(Context context, Intent intent) {            Toast.makeText(context, "network change", Toast.LENGTH_SHORT).show();        }    }}