android - 在 android 中检查互联网连接

Question

我正在开发一个检查互联网是否可用的应用程序...

我正在从 this 获得帮助.

这是我的连接类:

  public class ChechConnection {

private Context _context;

public ChechConnection(Context context){
    this._context = context;
}

public boolean isConnectingToInternet(){
    ConnectivityManager connectivity = (ConnectivityManager) _context.getSystemService(Context.CONNECTIVITY_SERVICE);
      if (connectivity != null) 
      {
          NetworkInfo[] info = connectivity.getAllNetworkInfo();
          if (info != null) 
              for (int i = 0; i < info.length; i++) 
                  if (info[i].getState() == NetworkInfo.State.CONNECTED)
                  {
                      return true;
                  }

      }
      return false;
}
}

我正在使用这段代码进行检查:这是充值 Activity 类的代码

ChechConnection cDetactor;
Boolean isInternetPresent = false;

如果有人点击一个按钮，如果有互联网连接，它应该会显示一些东西。

 cDetactor=new ChechConnection(getApplicationContext());
 isInternetPresent = cDetactor.isConnectingToInternet();


   btn_recharge.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
         if (isInternetPresent){
        Toast.makeText(mContext,"Button Pressed",Toast.LENGTH_LONG).show();
        }
        else
            alert.showAlertDialog(mContext,"Check Connection","Check Your Connection Setting",false);
    }
});

这是我自己的对话管理器:

公共(public)类 ALertDialogManager {

public void showAlertDialog(final Context context, String title, String message,
        Boolean status) {
    final Dialog alertDialog = new Dialog(new ContextThemeWrapper(context, android.R.style.Theme_Translucent));
    alertDialog.requestWindowFeature(Window.FEATURE_NO_TITLE); 
    alertDialog.setCancelable(true);
    alertDialog.setContentView(R.layout.dialog);
    alertDialog.setTitle(title);

   Button ok=(Button) alertDialog.findViewById(R.id.btncancel);
   Button cancel=(Button) alertDialog.findViewById(R.id.btnsearch);
   ok.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {

        Activity activity=(Activity) context;
        activity.finish();
    }
});
   cancel.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        alertDialog.dismiss();
    }
});

    alertDialog.show();
}

但是如果有 Internet 连接，它会给我一个错误。请检查我的 logcat 值:

04-29 11:26:15.011: E/AndroidRuntime(2177): Process: com.example.lifegoal, PID: 2177
04-29 11:26:15.011: E/AndroidRuntime(2177): java.lang.NullPointerException: Attempt to invoke virtual method 'void com.lifegoal.eshop.helper.ALertDialogManager.showAlertDialog(android.content.Context, java.lang.String, java.lang.String, java.lang.Boolean)' on a null object reference
04-29 11:26:15.011: E/AndroidRuntime(2177):     at com.lifegoal.eshop.Recharge_Activity$1.onClick(Recharge_Activity.java:51)

但如果有 Internet 连接，它会转到其他部分并给我那个 logcat 值

谢谢!

Answer 1

使用这个方法:

public static boolean isDeviceOnline(Context context) {
        boolean isConnectionAvail = false;
        try {
            ConnectivityManager cm = (ConnectivityManager) context
                    .getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo netInfo = cm.getActiveNetworkInfo();
            if(netInfo != null)
            return netInfo.isConnected();
            else 
                return isConnectionAvail;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return isConnectionAvail;
    }