檢查，如果Android設備連接到網絡

-2

如果將它連接，用戶應該能夠登錄。

如果不是這樣，用戶應該得到一個錯誤信息，告訴：

首次登錄前連接到網絡......

下面是我的代碼：

login.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 


       username = user.getText().toString(); 
       password = pass.getText().toString(); 
       DatabaseOperations dop = new DatabaseOperations(ctx); 
       Cursor cr = dop.getInformation(dop); 
       cr.moveToFirst(); 
       boolean loginstatus=false; 
       String Name= ""; 
       do 
       { 
        if(username.equals(cr.getString(2))&& (password.equals(cr.getString(3)))) 
        { 
         loginstatus=true; 
         Name = cr.getString(0); 
        } 


       }while(cr.moveToNext()); 
       if(loginstatus) 
       { 
        Toast.makeText(ctx, "Welcome \n" + Name, Toast.LENGTH_LONG).show(); 
        Intent i = new Intent(ctx, MainActivity.class); 
        startActivity(i); 
        finish(); 
       }else 
       { 
        Toast.makeText(ctx, "Check your Credentials..", Toast.LENGTH_LONG).show(); 
       } 
       } 

     });

來源

2017-04-20 kim gonzales

你的問題是重複的：（http://stackoverflow.com/questions/1560788/how-to-check-internet-access-on-android-inetaddress-never-times-out） –

[如何檢查網絡連接的可能的複製在Android上訪問？ InetAddress類永不超時（http://stackoverflow.com/questions/1560788/how-to-check-internet-access-on-android-inetaddress-never-times-out） –

創建廣播接收器從操作系統接收網絡事件：

public class ConnectivityReceiver extends BroadcastReceiver { 
    private boolean isConnected = false; 

    @Override 
    public void onReceive(Context context, Intent intent) { 
     if (intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION)) { 
      ConnectivityManager cm = 
        (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); 

      NetworkInfo activeNetwork = cm.getActiveNetworkInfo(); 
      isConnected = activeNetwork != null && 
        activeNetwork.isAvailable(); 

      if (isConnected) { 
       onConnectionRestored(); 
      } else { 
       onConnectionInterrupted(); 
      } 
     } 
    } 

    private void onConnectionRestored() { //implement me } 
    private void onConnectionInterrupted() { //implement me } 

}

然後將其註冊您的活動/片段/主持人的onStart()方法來啓動監聽：

connectivityReceiver = new ConnectivityReceiver(); 
IntentFilter intentFilter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION); 
registerReceiver(connectivityReceiver, intentFilter);

不要忘記註銷當您完成：

@Override 
protected void onStop() { 
    unregisterReceiver(connectivityReceiver); 
    super.onStop(); 
}

來源

2017-04-20 00:39:02 feresr

太感謝你了，現在我會嘗試。 –

方法getApplicationContext（）未定義類型ConnectivityReceiver isConnected無法解析爲變量 onConnectionRestored（）方法未定義類型ConnectivityReceiver 爲什麼我得到此錯誤？我似乎無法找到問題 –

用'上下文'替換'getApplicationContext（）'。編輯我的回答 – feresr

您可以使用廣播接收機檢查互聯網連接或不在下面。

MainActivity.Java

import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.content.IntentFilter; 
import android.graphics.Color; 
import android.net.ConnectivityManager; 
import android.net.NetworkInfo; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.widget.TextView; 

public class MainActivity extends AppCompatActivity { 
    private static TextView internetStatus; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     internetStatus = (TextView) findViewById(R.id.internet_status); 

     // At activity startup we manually check the internet status and change 
     // the text status 
     ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); 
     NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo(); 
     if (networkInfo != null && networkInfo.isConnected()) { 
      changeTextStatus(true); 
     } else { 
      changeTextStatus(false); 
     } 
    } 
    // Method to change the text status 
    public void changeTextStatus(boolean isConnected) { 

     // Change status according to boolean value 
     if (isConnected) { 
      internetStatus.setText("Internet Connected."); 
      internetStatus.setTextColor(Color.parseColor("#00ff00")); 
     } else { 
      internetStatus.setText("Internet Disconnected."); 
      internetStatus.setTextColor(Color.parseColor("#ff0000")); 
     } 
    } 

    @Override 
    protected void onPause() { 

     super.onPause(); 
     MyApplication.activityPaused();// On Pause notify the Application 
    } 

    @Override 
    protected void onResume() { 

     super.onResume(); 
     MyApplication.activityResumed();// On Resume notify the Application 
    } 
}

Receiver.Java

import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.net.ConnectivityManager; 
import android.net.NetworkInfo; 
import android.util.Log; 

/** 
* Created by root on 7/4/17. 
*/ 
public class Receiver extends BroadcastReceiver { 
    @Override 
    public void onReceive(Context context, Intent intent) { 
     try { 

      boolean isVisible = MyApplication.isActivityVisible();// Check if 
      // activity 
      // is 
      // visible 
      // or not 
      Log.i("ActivityVisible ", "visible : " + isVisible); 

      // If it is visible then trigger the task else do nothing 
      if (isVisible == true) { 
       ConnectivityManager connectivityManager = (ConnectivityManager) context 
         .getSystemService(Context.CONNECTIVITY_SERVICE); 
       NetworkInfo networkInfo = connectivityManager 
         .getActiveNetworkInfo(); 

       // Check internet connection and accrding to state change the 
       // text of activity by calling method 
       if (networkInfo != null && networkInfo.isConnected()) { 

        new MainActivity().changeTextStatus(true); 
        Log.i("ActivityVisible ", "visible : " + isVisible); 
       } else { 
        new MainActivity().changeTextStatus(false); 
       } 
      } 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 


    } 
}

MyApplication.Java

public class MyApplication extends Application { 
    // Gloabl declaration of variable to use in whole app 

    public static boolean activityVisible; // Variable that will check the 
    // current activity state 

    public static boolean isActivityVisible() { 
     return activityVisible; // return true or false 
    } 

    public static void activityResumed() { 
     activityVisible = true;// this will set true when activity resumed 

    } 

    public static void activityPaused() { 
     activityVisible = false;// this will set false when activity paused 

    } 

}

Manifest.Java

<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.theme.broadcastreceiver"> 

    <uses-permission android:name="android.permission.INTERNET" /> 
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> 
    <!-- This permissions are neccessary for broadcast receiver --> 
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> 

    <application 
     android:allowBackup="true" 
     android:icon="@mipmap/ic_launcher" 
     android:label="@string/app_name" 
     android:supportsRtl="true" 
     android:theme="@style/AppTheme"> 
     <activity android:name=".MainActivity"> 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
     <receiver 
      android:name=".Receiver" 
      android:enabled="true" > 
      <intent-filter> 

       <!-- Intent filters for broadcast receiver --> 
       <action android:name="android.net.conn.CONNECTIVITY_CHANGE" /> 
       <action android:name="android.net.wifi.WIFI_STATE_CHANGED" /> 
       <action android:name="android.net.wifi.STATE_CHANGE" /> 
      </intent-filter> 
     </receiver> 
    </application> 

</manifest>

來源

2017-04-20 06:12:15 pradeep

檢查，如果Android設備連接到網絡

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