Android检测网络状态，开启Wifi

private boolean CheckWifiNetworkStatus() {
       boolean flag = false;
       ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
       if (manager.getActiveNetworkInfo() != null){
           flag = manager.getActiveNetworkInfo().isAvailable();
       }
       if (!flag) {
           Builder b = new AlertDialog.Builder(this).setTitle("没有可用的GPRS或WIFI网络").setMessage("开启GPRS或WIFI网络连接");
           b.setPositiveButton("确定", new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int whichButton) {
                   Intent mIntent = new Intent("/");
                   ComponentName comp = new ComponentName("com.android.settings", "com.android.settings.WirelessSettings");
                   mIntent.setComponent(comp);
                   mIntent.setAction("android.intent.action.VIEW");
                   startActivity(mIntent);
               }
           }).setNeutralButton("取消", new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int whichButton) {
                   dialog.cancel();
               }
           }).create();
           b.show();
       }
       return flag;
   }

在AndroidManifest.xml中加入权限

    <!-- Internet Permissions -->
    <uses-permission android:name="android.permission.INTERNET" />

    <!-- Network State Permissions -->
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />