判断网络是否可用并打开WIFI设置

        ConnectivityManager manager = (ConnectivityManager) this
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo info = manager.getActiveNetworkInfo();
        if (info != null && info.isAvailable()) {
            Toast.makeText(this, "网络可用", Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(this, "网络不可用", Toast.LENGTH_SHORT).show();
            Intent intent = new Intent();
            intent.setAction(Settings.ACTION_WIFI_SETTINGS);
            this.startActivity(intent);
        }

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />