当我在没有连接 WiFi 的情况下打开我的 android 应用程序时，它显示没有连接 WiFi，正如我在代码中给出的那样答案

【问题标题】：when i open my android app when no WiFi connected it show no WiFi connected as i given in the code当我在没有连接 WiFi 的情况下打开我的 android 应用程序时，它显示没有连接 WiFi，正如我在代码中给出的那样
【发布时间】：2018-11-08 06:45:12
【问题描述】：

但是当我用 WiFi 连接我的应用程序时，它仍然显示没有连接 WiFi，所以我必须关闭应用程序并在连接 WiFi 的情况下再次打开它。

if (wifimanager.setWifiEnabled(true)) {
      punchin.setOnClickListener {

          if ((conMgr.activeNetworkInfo != null) && (wifi.isAvailable == true && wifi.isConnected == true)) {

              Log.v("MAc", "mac=" + wMAC + "\n" + wbssid + "\n" + wssid)

              if ((wbssid == "") && (wssid.equals(""))
                      && conMgr.activeNetworkInfo != null && conMgr.activeNetworkInfo.isAvailable
                      && conMgr.activeNetworkInfo.isConnected) {

                  textView.text = "Connected to correct Wifi"
                  punchout.visibility = View.VISIBLE

              } else if (wbssid!="") {

                  Toast.makeText(applicationContext, "Connect To Correct Wifi", Toast.LENGTH_LONG).show()
              }
          } else {

              Toast.makeText(this, "No Wifi Connection", Toast.LENGTH_LONG).show()
          }
      }
  }

【问题讨论】：

WiFi 连接时是否显示消息？
你从哪里调用这些代码？

标签： android android-connectivitymanager

【解决方案1】：

如果你想监听连接变化状态，你需要添加一个接收器。检查下面的代码 -

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


    private void registerBroadCastReceiver() {
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);
        registerReceiver(receiver, intentFilter);
    }

    private void checkWifiConnectionStatus() {
        WifiManager wifiMgr = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);

        if (wifiMgr.isWifiEnabled()) {
            WifiInfo wifiInfo = wifiMgr.getConnectionInfo();

            if (wifiInfo.getNetworkId() == -1) {
                Toast.makeText(this, "Disconnected", Toast.LENGTH_SHORT).show();
                return;
            }
            Toast.makeText(this, "Connected", Toast.LENGTH_SHORT).show();
            return;
        } else {
            Toast.makeText(this, "Disconnected", Toast.LENGTH_SHORT).show();
            return;
        }
    }

    BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            checkWifiConnectionStatus();
        }
    };

【讨论】：

【解决方案2】：

在您的活动中注册广播接收器，并在该接收器中通过连接管理器监视连接状态，当连接状态更改时调用该方法来执行您的任务。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
       BroadcastReceiver  netReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
                NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
                boolean isConnected = activeNetwork != null && activeNetwork.isConnectedOrConnecting();
                if (isConnected) {
                    try {
                        performTask(isConnected);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                } else {
                    performTask(isConnected);
                }
            }
        };
    }



public void performTask(boolean isConnected) {
    if (isConnected) {
        Log.i("test", "connection successfull");
    } else {
        Log.i("test", "connection failed");
    }
}

并在清单中添加以下权限

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />

【讨论】：