Android：检测网络状态&监听网络变化

getAllNetworks();
getNetworkInfo(android.net.Network);
getNetworkInfo(Network network);

//检测当前的网络状态

//API版本23以下时调用此方法进行检测
//因为API23后getNetworkInfo(int networkType)方法被弃用
    public void checkState_21(){
        //步骤1：通过Context.getSystemService(Context.CONNECTIVITY_SERVICE)获得ConnectivityManager对象
       ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

        //步骤2：获取ConnectivityManager对象对应的NetworkInfo对象
        //NetworkInfo对象包含网络连接的所有信息
        //步骤3：根据需要取出网络连接信息
        //获取WIFI连接的信息
        NetworkInfo networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
        Boolean isWifiConn = networkInfo.isConnected();

        //获取移动数据连接的信息
        networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
        Boolean isMobileConn = networkInfo.isConnected();
        tv_WiFistate.setText("Wifi是否连接:" + isWifiConn);
        tv_Network_state.setText("移动数据是否连接:" + isMobileConn);
    }

//API版本23及以上时调用此方法进行网络的检测
//步骤非常类似
    public void checkState_21orNew(){
        //获得ConnectivityManager对象
        ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

        //获取所有网络连接的信息
        Network[] networks = connMgr.getAllNetworks();
        //用于存放网络连接信息
        StringBuilder sb = new StringBuilder();
        //通过循环将网络信息逐个取出来
        for (int i=0; i < networks.length; i++){
        //获取ConnectivityManager对象对应的NetworkInfo对象
            NetworkInfo networkInfo = connMgr.getNetworkInfo(networks[i]);
            sb.append(networkInfo.getTypeName() + " connect is " + networkInfo.isConnected());
        }
    }

package scut.carson_ho.check_net;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.Network;
import android.net.NetworkInfo;
import android.widget.Toast;

/**
 * Created by Carson_Ho on 16/10/31.
 */
public class NetWorkStateReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {

        System.out.println("网络状态发生变化");
        //检测API是不是小于23，因为到了API23之后getNetworkInfo(int networkType)方法被弃用
        if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.LOLLIPOP) {

            //获得ConnectivityManager对象
            ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

            //获取ConnectivityManager对象对应的NetworkInfo对象
            //获取WIFI连接的信息
            NetworkInfo wifiNetworkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
            //获取移动数据连接的信息
            NetworkInfo dataNetworkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
            if (wifiNetworkInfo.isConnected() && dataNetworkInfo.isConnected()) {
                Toast.makeText(context, "WIFI已连接,移动数据已连接", Toast.LENGTH_SHORT).show();
            } else if (wifiNetworkInfo.isConnected() && !dataNetworkInfo.isConnected()) {
                Toast.makeText(context, "WIFI已连接,移动数据已断开", Toast.LENGTH_SHORT).show();
            } else if (!wifiNetworkInfo.isConnected() && dataNetworkInfo.isConnected()) {
                Toast.makeText(context, "WIFI已断开,移动数据已连接", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(context, "WIFI已断开,移动数据已断开", Toast.LENGTH_SHORT).show();
            }
//API大于23时使用下面的方式进行网络监听
        }else {

            System.out.println("API level 大于23");
            //获得ConnectivityManager对象
            ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

            //获取所有网络连接的信息
            Network[] networks = connMgr.getAllNetworks();
            //用于存放网络连接信息
            StringBuilder sb = new StringBuilder();
            //通过循环将网络信息逐个取出来
            for (int i=0; i < networks.length; i++){
                //获取ConnectivityManager对象对应的NetworkInfo对象
                NetworkInfo networkInfo = connMgr.getNetworkInfo(networks[i]);
                sb.append(networkInfo.getTypeName() + " connect is " + networkInfo.isConnected());
            }
            Toast.makeText(context, sb.toString(),Toast.LENGTH_SHORT).show();
        }
    }
}

package scut.carson_ho.check_net;

import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    NetWorkStateReceiver netWorkStateReceiver;

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

    //在onResume()方法注册
    @Override
    protected void onResume() {
        if (netWorkStateReceiver == null) {
            netWorkStateReceiver = new NetWorkStateReceiver();
        }
        IntentFilter filter = new IntentFilter();
        filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        registerReceiver(netWorkStateReceiver, filter);
        System.out.println("注册");
        super.onResume();
    }

    //onPause()方法注销
    @Override
    protected void onPause() {
        unregisterReceiver(netWorkStateReceiver);
        System.out.println("注销");
        super.onPause();
    }
}

<receiver android:name=".NetWorkStateReceiver">  
    <intent-filter>  
//检测网络变化的acton
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>  
        <category android:name="android.intent.category.DEFAULT" />  
    </intent-filter>  
</receiver>  

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