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);
        intentFilter=new IntentFilter();
        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
        networkChangeReceiver = new NetworkChangeReceiver();
        registerReceiver(networkChangeReceiver,intentFilter);
    }
 
    @Override
    protected void onDestroy(){
        super.onDestroy();
        unregisterReceiver(networkChangeReceiver);
    }
 
private final  class NetworkChangeReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent){
      ConnectivityManager cm=(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
      NetworkInfo networkInfo= cm.getActiveNetworkInfo();
      if(networkInfo == null){
        // WIFI 和 移動網絡都關閉 即沒有有效網絡
        Log.e(TAG, "當前無網絡連接");
        return;
      }
      String typeName = "";
      if(networkInfo.getType()==ConnectivityManager.TYPE_WIFI){
        //WIFI網絡跳轉的頁面.
        typeName = networkInfo.getTypeName();//==> WIFI
      }else if(networkInfo.getType()==ConnectivityManager.TYPE_MOBILE) {
        //無線網絡跳轉的頁面
        typeName = networkInfo.getTypeName();//==> MOBILE
      }
      Log.e(TAG, "==>" + typeName);
      Log.e(TAG, "==>" + networkInfo.getDetailedState());
    }
  }
}

概況

ConnectivityManager主要職責，官方說明：

Monitor network connections (Wi-Fi, GPRS, UMTS, etc.)

Send broadcast intents when network connectivity changes

Attempt to “fail over” to another network when connectivity to a network is lost

Provide an API that allows applications to query the coarse-grained or fine-grained state of the available networks

Provide an API that allows applications to request and select networks for their data traffic

平民翻譯：

監控網絡連接(Wi-Fi, GPRS, UMTS, etc.)；
當網絡連接改變時發送Intent；
當連接到一個網絡失敗時，嘗試用其他網絡補救；
提供API給應用查詢有效網絡粗略或者精確的狀態；
提供API給應用爲它們的數據傳輸請求和選擇網絡；

實踐概要

NetworkInfo 實踐詳解

名稱	說明
isConnected()	判斷網絡連接是否存在
isAvailable()	判斷網絡連接（注：isConnected爲true，不代表isAvailable爲true）
getDetailedState()	（詳細）報告當前網絡狀態 getState()報告當前網絡狀態
getExtrInfo()	報告關於網絡狀態的額外信息，由較低的網絡層提供的
getType()	獲取當前網絡的類型和ConnectivityManager.TYPE_**對比
getTypeName()	獲取當前網絡的類型名如 “WIFI” or “MOBILE”

注意:

isConnected() 和 isAvailable() 都爲true 不能保證能正常連接到服務器，解決方案用ping命令，參考ShellUtil.execCmd：

//ShellUtil.CommandResult result = ShellUtil.execCmd(String.format("ping -c 1 %s", ip), false);
String[] command = new String[]{String.format("ping -c 1 %s", ip)};
int result = -1;
Process process = Runtime.getRuntime().exec(isRoot ? "su" : "sh");
DataOutputStream os = new DataOutputStream(process.getOutputStream());
for (String command : commands) {
    if (command == null) continue;
    os.write(command.getBytes());
    os.writeBytes(LINE_SEP);
    os.flush();
}
os.writeBytes("exit" + LINE_SEP);
os.flush();
result = process.waitFor();

getDetailedState/getState 直接看NetworkInfo源碼getState等到的值爲

public enum State {
    CONNECTING, CONNECTED, SUSPENDED, DISCONNECTING, DISCONNECTED, UNKNOWN
}

getExtrInfo() WIFI鏈接返回SSID名稱，移動網絡返回APN（Access Point Name）,電信物聯網得卡到列如：ctnet或ctwap

ConnectivityManager 實踐詳解

ConnectivityManager類按照其主要職能，常用方法大致可分爲三類：

獲取網絡鏈接信息getXXX如getActiveNetwork，getDefaultProxy
多網絡鏈接綁定指定網絡 bindsocket和bindprocesstonetwork（6.0的系統 api>23）
監聽類型 registerDefaultNetworkCallback/registerNetworkCallback

方法	詳解
addDefaultNetworkActiveListener	在網絡有一定量的數據傳輸時間隔調用，可用於鏈接優化

 cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    cm.addDefaultNetworkActiveListener(new ConnectivityManager.OnNetworkActiveListener() {
      @Override public void onNetworkActive() {
        Log.e(TAG, "Active ==>"); //無論是否成功鏈接外網，只要有一定量的數據傳輸就會間隔有回調
      }
    });

方法	詳解
bindProcessToNetwork	多網絡同時鏈接時指定網絡鏈接

應用場景：

手機同時連接移動網絡和本地局域網，手機所有的連接默認訪問移動網絡，需要手機連接本地局域網：
Okhttp,picasso與glidez指定網絡訪問的案例

方法	詳解
registerNetworkCallback	指定網絡監聽的內容回調

 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP/*5.0*/) {
      ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
      // 請注意這裏會有一個版本適配bug，所以請在這裏添加非空判斷
      if (connectivityManager != null) {
        NetworkRequest.Builder builder = new NetworkRequest.Builder();

        NetworkRequest request = builder.addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
            .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
            .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
            .build();

        connectivityManager.registerNetworkCallback(request,new ConnectivityManager.NetworkCallback(){

          /**
           * 網絡可用的回調連接成功
           * */
          @Override public void onAvailable(Network network) {
            super.onAvailable(network);
            Log.e(TAG, "onAvailable ==>" + network.toString());
          }

          /**
           * 實踐中在網絡連接正常的情況下，丟失數據會有回調
           * */
          @Override public void onLosing(Network network, int maxMsToLive) {
            super.onLosing(network, maxMsToLive);
            Log.e(TAG, "onLosing ==>" + network.toString() + " max==>" + maxMsToLive);
          }

          /**
           * 網絡不可用時調用和onAvailable成對出現
           */
          @Override public void onLost(Network network) {
            super.onLost(network);
            Log.e(TAG, "onLost ==>" + network.toString());
          }

          @Override public void onUnavailable() {
            super.onUnavailable();
            Log.e(TAG, "onUnavailable ==>");
          }

          /**
           * 字面直接能理解
           * @param network 新連接網絡
           * @param networkCapabilities 新連接網絡的一些能力參數
           */
          @Override
          public void onCapabilitiesChanged(Network network, NetworkCapabilities networkCapabilities) {
            super.onCapabilitiesChanged(network, networkCapabilities);
            Log.e(TAG, "onCapabilitiesChanged ==>" + networkCapabilities.toString());
            //WIFI -> CELLULAR
            //[ Transports: CELLULAR Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED&NOT_VPN&VALIDATED LinkUpBandwidth>=51200Kbps LinkDnBandwidth>=102400Kbps Specifier: <3>]
            //CELLULAR -> WIFI
            //==>[ Transports: WIFI Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED&NOT_VPN&VALIDATED LinkUpBandwidth>=1048576Kbps LinkDnBandwidth>=1048576Kbps SignalStrength: -42]
          }
        
          /**
           * 和上面類似，但是沒有試出效果
           */
          @Override
          public void onLinkPropertiesChanged(Network network, LinkProperties linkProperties) {
            super.onLinkPropertiesChanged(network, linkProperties);
            Log.e(TAG, "onLinkPropertiesChanged ==>" + linkProperties.toString());
          }
        });
      }
    }

更多監聽內容設置請訪問官網NetworkRequest

Network 淺析

從源碼中可以得出Network就是一個Parcelable數據，最重要的參數是

public final int netId;

在回想一下Network什麼時候第一次獲得

@Override public void onAvailable(Network network)

如果到這裏還啥都不get代碼意圖，那看Network提供的方法

public InetAddress[] getAllByName(String host) throws UnknownHostException {
    return InetAddress.getAllByNameOnNet(host, netId);
}

public InetAddress getByName(String host) throws UnknownHostException {
    return InetAddress.getByNameOnNet(host, netId);
}

bindSocket(Socket socket)
getSocketFactory()
openConnection(URL url)
openConnection(URL url, Proxy proxy)

好到此我的理解是在網絡連接onAvailable成功後,返回基於netId的底層網絡標識，可以基於這個Network建立一些特殊的URL訪問；

實用工具

NetUtil.java

//NetUtils.java
 private static final int NETWORK_TYPE_GSM = 16;
  private static final int NETWORK_TYPE_TD_SCDMA = 17;
  private static final int NETWORK_TYPE_IWLAN = 18;
 /**
   * 判斷網絡是否可用
   * <p>需要異步 ping，如果 ping 不通就說明網絡不可用</p>
   *
   * @param ip ip 地址（自己服務器 ip），如果爲空，ip 爲阿里巴巴公共 ip
   * @return {@code true}: 可用<br>{@code false}: 不可用
   */
  public static boolean isAvailableByPing(String ip) {
    if (ip == null || ip.length() <= 0) {
      // 阿里巴巴公共 ip
      ip = "223.5.5.5";
    }
    ShellUtil.CommandResult result = ShellUtil.execCmd(String.format("ping -c 1 %s", ip), false);
    boolean ret = result.result == 0;
    if (result.successMsg != null) {
      Log.d("NetUtil", "isAvailableByPing() called" + result.successMsg);
    }
    if (result.errorMsg != null) {
      Log.d("NetUtil", "isAvailableByPing() called" + result.errorMsg);
    }
    return ret;
  }

  /**
   * 判斷移動數據是否打開
   *
   * @return {@code true}: 是<br>{@code false}: 否
   */
  public static boolean isMobileDataEnabled() {
    try {
      TelephonyManager tm = (TelephonyManager) Utils.getApp().getSystemService(Context.TELEPHONY_SERVICE);
      Method getMobileDataEnabledMethod = tm.getClass().getDeclaredMethod("getDataEnabled");
      if (getMobileDataEnabledMethod != null) {
        return (boolean) getMobileDataEnabledMethod.invoke(tm);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
    return false;
  }

  /**
   * 打開或關閉移動數據
   *
   * @param enabled {@code true}: 打開<br>{@code false}: 關閉
   */
  public static void setMobileDataEnabled(boolean enabled) {
    try {
      TelephonyManager tm = (TelephonyManager) Utils.getApp().getSystemService(Context.TELEPHONY_SERVICE);
      Method setMobileDataEnabledMethod = tm.getClass().getDeclaredMethod("setDataEnabled", boolean.class);
      if (null != setMobileDataEnabledMethod) {
        setMobileDataEnabledMethod.invoke(tm, enabled);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

  private enum NetworkType {
    // wifi
    NETWORK_WIFI,
    // 4G 網
    NETWORK_4G,
    // 3G 網
    NETWORK_3G,
    // 2G 網
    NETWORK_2G,
    // 未知網絡
    NETWORK_UNKNOWN,
    // 沒有網絡
    NETWORK_NO
  }

  /**
   * 獲取當前網絡類型
   *
   * @return 網絡類型
   * <ul>
   * <li>{@link NetworkType#NETWORK_WIFI   } </li>
   * <li>{@link NetworkType#NETWORK_4G     } </li>
   * <li>{@link NetworkType#NETWORK_3G     } </li>
   * <li>{@link NetworkType#NETWORK_2G     } </li>
   * <li>{@link NetworkType#NETWORK_UNKNOWN} </li>
   * <li>{@link NetworkType#NETWORK_NO     } </li>
   * </ul>
   */
  public static NetworkType getNetworkType() {
    NetworkType netType = NetworkType.NETWORK_NO;
    NetworkInfo info = getActiveNetworkInfo();
    if (info != null && info.isAvailable()) {
      if (info.getType() == ConnectivityManager.TYPE_WIFI) {
        netType = NetworkType.NETWORK_WIFI;
      } else if (info.getType() == ConnectivityManager.TYPE_MOBILE) {
        switch (info.getSubtype()) {

          case NETWORK_TYPE_GSM:
          case TelephonyManager.NETWORK_TYPE_GPRS:
          case TelephonyManager.NETWORK_TYPE_CDMA:
          case TelephonyManager.NETWORK_TYPE_EDGE:
          case TelephonyManager.NETWORK_TYPE_1xRTT:
          case TelephonyManager.NETWORK_TYPE_IDEN:
            netType = NetworkType.NETWORK_2G;
            break;

          case NETWORK_TYPE_TD_SCDMA:
          case TelephonyManager.NETWORK_TYPE_EVDO_A:
          case TelephonyManager.NETWORK_TYPE_UMTS:
          case TelephonyManager.NETWORK_TYPE_EVDO_0:
          case TelephonyManager.NETWORK_TYPE_HSDPA:
          case TelephonyManager.NETWORK_TYPE_HSUPA:
          case TelephonyManager.NETWORK_TYPE_HSPA:
          case TelephonyManager.NETWORK_TYPE_EVDO_B:
          case TelephonyManager.NETWORK_TYPE_EHRPD:
          case TelephonyManager.NETWORK_TYPE_HSPAP:
            netType = NetworkType.NETWORK_3G;
            break;

          case NETWORK_TYPE_IWLAN:
          case TelephonyManager.NETWORK_TYPE_LTE:
            netType = NetworkType.NETWORK_4G;
            break;
          default:

            String subtypeName = info.getSubtypeName();
            //  中國移動 聯通 電信 三種 3G 制式
            if (subtypeName.equalsIgnoreCase("TD-SCDMA")
                || subtypeName.equalsIgnoreCase("WCDMA")
                || subtypeName.equalsIgnoreCase("CDMA2000")) {
              netType = NetworkType.NETWORK_3G;
            } else {
              netType = NetworkType.NETWORK_UNKNOWN;
            }
            break;
        }
      } else {
        netType = NetworkType.NETWORK_UNKNOWN;
      }
    }
    return netType;
  }

谷歌API之ConnectivityManager實戰全解析（3天沉澱內容9分鐘掌握）

目錄

最小案例

概況

實踐概要

NetworkInfo 實踐詳解

ConnectivityManager 實踐詳解

Network 淺析

實用工具

參考

“Cannot call this method while RecyclerView is computing a layout”異常解決

谷歌API之ConnectivityManager實戰全解析（3天沉澱內容9分鐘掌握）

最實用的Android Debug Bridge (ADB)使用手冊

完美簡單解決git和svn共用混用，或用git維護svn的問題

阿里巴巴arouter組件化總結

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

linux以太網驅動總結