本文共 11789 字，大约阅读时间需要 39 分钟。

最小案例

需要的权限

MainActivity.java

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 移动网络都关闭 即没有有效网络        Log.e(TAG, "当前无网络连接");        return;      }      String typeName = "";      if(networkInfo.getType()==ConnectivityManager.TYPE_WIFI){        //WIFI网络跳转的页面.        typeName = networkInfo.getTypeName();//==> WIFI      }else if(networkInfo.getType()==ConnectivityManager.TYPE_MOBILE) {        //无线网络跳转的页面        typeName = networkInfo.getTypeName();//==> MOBILE      }      Log.e(TAG, "==>" + typeName);      Log.e(TAG, "==>" + networkInfo.getDetailedState());    }  }}

概况

ConnectivityManager主要职责，官方说明：

1. Monitor network connections (Wi-Fi, GPRS, UMTS, etc.)
2. Send broadcast intents when network connectivity changes
3. Attempt to "fail over" to another network when connectivity to a network is lost
4. Provide an API that allows applications to query the coarse-grained or fine-grained state of the available networks
5. Provide an API that allows applications to request and select networks for their data traffic

平民翻译：

1. 监控网络连接(Wi-Fi, GPRS, UMTS, etc.)；
2. 当网络连接改变时发送Intent；
3. 当连接到一个网络失败时，尝试用其他网络补救；
4. 提供API给应用查询有效网络粗略或者精确的状态；
5. 提供API给应用为它们的数据传输请求和选择网络；

实践概要

NetworkInfo 实践详解

<font size=10 face=STHupo color=red>注意: </font>

• isConnected() 和 isAvailable() 都为true 不能保证能正常连接到服务器，解决方案用ping命令，参考：

//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源码getState等到的值为

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

• getExtrInfo() WIFI链接返回SSID名称，移动网络返回APN（Access Point Name）,电信物联网得卡到列如：ctnet或ctwap

ConnectivityManager 实践详解

ConnectivityManager类按照其主要职能，常用方法大致可分为三类：

• 获取网络链接信息getXXX如getActiveNetwork，getDefaultProxy
• 多网络链接绑定指定网络 bindsocket和bindprocesstonetwork（6.0的系统 api>23）
• 监听类型 registerDefaultNetworkCallback/registerNetworkCallback

cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);    cm.addDefaultNetworkActiveListener(new ConnectivityManager.OnNetworkActiveListener() {      @Override public void onNetworkActive() {        Log.e(TAG, "Active ==>"); //无论是否成功链接外网，只要有一定量的数据传输就会间隔有回调      }    });

应用场景：

• 手机同时连接移动网络和本地局域网，手机所有的连接默认访问移动网络，需要手机连接本地局域网：

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP/*5.0*/) {      ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);      // 请注意这里会有一个版本适配bug，所以请在这里添加非空判断      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(){          /**           * 网络可用的回调连接成功           * */          @Override public void onAvailable(Network network) {            super.onAvailable(network);            Log.e(TAG, "onAvailable ==>" + network.toString());          }          /**           * 实践中在网络连接正常的情况下，丢失数据会有回调           * */          @Override public void onLosing(Network network, int maxMsToLive) {            super.onLosing(network, maxMsToLive);            Log.e(TAG, "onLosing ==>" + network.toString() + " max==>" + maxMsToLive);          }          /**           * 网络不可用时调用和onAvailable成对出现           */          @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 新连接网络           * @param networkCapabilities 新连接网络的一些能力参数           */          @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]          }                  /**           * 和上面类似，但是没有试出效果           */          @Override          public void onLinkPropertiesChanged(Network network, LinkProperties linkProperties) {            super.onLinkPropertiesChanged(network, linkProperties);            Log.e(TAG, "onLinkPropertiesChanged ==>" + linkProperties.toString());          }        });      }    }

更多监听内容设置请访问官网

Network 浅析

从源码中可以得出Network就是一个Parcelable数据，最重要的参数是

public final int netId;

在回想一下Network什么时候第一次获得

@Override public void onAvailable(Network network)

如果到这里还啥都不get代码意图，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网络连接onAvailable成功后,返回基于netId的底层网络标识，可以基于这个Network建立一些特殊的URL访问；

实用工具

//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; /**   * 判断网络是否可用   * 
需要异步 ping，如果 ping 不通就说明网络不可用
   *   * @param ip ip 地址（自己服务器 ip），如果为空，ip 为阿里巴巴公共 ip   * @return {@code true}: 可用
{@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;  }  /**   * 判断移动数据是否打开   *   * @return {@code true}: 是
{@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;  }  /**   * 打开或关闭移动数据   *   * @param enabled {@code true}: 打开
{@code false}: 关闭   */  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 网    NETWORK_4G,    // 3G 网    NETWORK_3G,    // 2G 网    NETWORK_2G,    // 未知网络    NETWORK_UNKNOWN,    // 没有网络    NETWORK_NO  }  /**   * 获取当前网络类型   *   * @return 网络类型   * 
   
       * 
    
{@link NetworkType#NETWORK_WIFI   } 
   * 
    
{@link NetworkType#NETWORK_4G     } 
   * 
    
{@link NetworkType#NETWORK_3G     } 
   * 
    
{@link NetworkType#NETWORK_2G     } 
   * 
    
{@link NetworkType#NETWORK_UNKNOWN} 
   * 
    
{@link NetworkType#NETWORK_NO     } 
   * 
   
   */  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();            //  中国移动 联通 电信 三种 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;  }

转载地址：https://liwangjiang.blog.csdn.net/article/details/88354233 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！