距以前寫安卓已經(jīng)有好幾年時間了，現(xiàn)在又要重新回顧一遍了，看到了廣播機制這塊了就寫了一個小Demo，過程中遇到了不少的問題，現(xiàn)在總結(jié)一下

import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private NetworkChangeReceiver networkChangeReceiver;

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

        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
        networkChangeReceiver = new NetworkChangeReceiver();
        registerReceiver(networkChangeReceiver,intentFilter);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(networkChangeReceiver);
        Log.i("取消注冊通知","已經(jīng)取消了");
    }

    class NetworkChangeReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            ConnectivityManager manager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo info = manager.getActiveNetworkInfo();
            if (info != null && info.isAvailable()) {
                Toast.makeText(context, "網(wǎng)絡(luò)狀態(tài)發(fā)生了變化 網(wǎng)絡(luò)可用", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(context, "網(wǎng)絡(luò)狀態(tài)發(fā)生了變化 網(wǎng)絡(luò)不可用", Toast.LENGTH_SHORT).show();
            }
        }
    }
}

以上是完整的源碼，在onCreate里邊添加了網(wǎng)絡(luò)狀態(tài)的接收器，當(dāng)然這個接收器是我們自己重寫系統(tǒng)后得到的特有接收器，專門用于網(wǎng)絡(luò)可用狀態(tài)監(jiān)控的。好吧，代碼寫好了跑一下吧，但發(fā)現(xiàn)一跑就崩潰，很苦惱，寫的都對啊，后來一看log才發(fā)現(xiàn)是因為權(quán)限問題，沒有向AndroidManifest.xml文件添加權(quán)限申請，記住這個很重要。

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