Android application setting connection type

问题

I'm writing an application for android. My problem is that I want it to force the connection in GPRS and not use wi fi. I have a solution like below, but this causes the crash of the application at start.

ConnectivityManager CM = 
    (ConnectivityManager) this.getSystemService(Context.CONNECTIVITY_SERVICE);
CM.setNetworkPreference(ConnectivityManager.TYPE_MOBILE);

I also added the below setting lines into manifest file.

uses-permission android:name="android.permission.WRITE_SETTINGS" 
uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" 
uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"
uses-permission android:name="android.permission.CHANGE_CONFIGURATION" 
uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS" 

Does anyone know the problem, or an answer to set connection type?

回答1:

My problem is that I want it to force the connection in GPRS and not use wi fi.

That is not possible in Android today, sorry.

回答2:

You are able to check to see if the Wi-Fi is on, and in Android 2.0 and above you are able to enable or disable the Wi-Fi programmatically. In Android 1.x, the best you can do is tell the user that they must disable it and point them to the Settings page.

/**
 * Checks if Wi-Fi is on. 
 * 
 * @return true, if Wi-fi is on.
 */
public static boolean isWiFiOn()
{
    WifiManager wifi = (WifiManager) MyAccountApplication.getContext().getSystemService(Context.WIFI_SERVICE);

    if (wifi == null)
        return false;

    List<WifiConfiguration> config = wifi.getConfiguredNetworks();

    if (config != null)
        for (int i = 0; i < config.size(); i++)
        {
            if (config.get(i).status == WifiConfiguration.Status.CURRENT)
            {
                return true;
            }
        }
    return false;
}

public static void setWiFi(Context context, boolean enabled)
{
    WifiManager wifi = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);

    if (wifi != null)
        wifi.setWifiEnabled(enabled);
}

来源：https://stackoverflow.com/questions/2230389/android-application-setting-connection-type