android BroadcastReceiver动态监听网络连接

当网络变化的时候系统会发出一个广播broadcast，只要在程序中注册一个广播接收器BroadcastReceiver，并在IntentFilter中添加相应的过滤，这样一旦网络有变化，程序就能监听到

package com.example.demo.myapplication.activity;

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

public abstract class BaseActivity extends AppCompatActivity {
private IntentFilter intentFilter;
private NetworkChangeReceiver networkChangeReceiver;
protected abstract void initView(Bundle savedInstanceState);

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

//监听网络变化
listenerNetwork();

initView(savedInstanceState);
}

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

private class NetworkChangeReceiver extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent) {

ConnectivityManager mConnectivityManager = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo mNetworkInfo = mConnectivityManager.getActiveNetworkInfo();
if (mNetworkInfo != null && mNetworkInfo.isAvailable()) {
Toast.makeText(context,"网络连接正常!!",Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(context,"网络连接异常!!",Toast.LENGTH_SHORT).show();
}

}
}

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

}

别忘了添加权限：

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