有的中国移动的业务需要走CMWAP接入点才能够连接网络的，在做这类应用的时候，不可避免地需要判断当前APN, 切换APN，以及成功连接到网络后连接到服务器。
首先，获取当前的APN有两种方式，一种是从当前系统的网络连接服务获取，即通过
ConnectivityManager conManager= (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = conManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
String currentAPN = info.getExtraInfo();
CurrentAPN为‘cmnet’或者’cmwap’。。。
还有一种是通过查询数据库的方式，因为我们设置的APN是存放在本地的xml中的
首先申明APN_URI:
public static final Uri CURRENT_APN_URI = Uri.parse("content://telephony/carriers/preferapn");
public static final Uri APN_LIST_URI = Uri.parse("content://telephony/carriers");
当前选中的APN记录在CURRENT_APN_URI中，而APN_LIST_URI里面是所以的APN列表。通过以下方法获取到选中的apn名字,
public static String getCurrentAPNFromSetting(ContentResolver resolver) {
Cursor cursor = null;
try {
cursor = resolver.query(CURRENT_APN_URI, null, null, null, null);
String curApnId = null;
if (cursor != null && cursor.moveToFirst()) {
curApnId = cursor.getString(cursor.getColumnIndex("apn_id"));
String apnName1 = cursor.getString(cursor.getColumnIndex("apn"));
}
cursor.close();
//find apn name from apn list
if (curApnId != null) {
cursor = resolver.query(APN_LIST_URI, null, " _id = ?", new String[]{curApnId}, null);
if (cursor != null && cursor.moveToFirst()) {
String apnName = cursor.getString(cursor.getColumnIndex("apn"));
return apnName;
}
}
} catch (SQLException e) {
Debug.error(e.getMessage());
} finally {
if (cursor != null) {
cursor.close();
}
}
return null;
}
获取到APN之后，需要判断是否是cmwap, 如果不是需要更改当前APN为cmwap. 可以通过改数据库的方式：
public static int updateCurrentAPN(ContentResolver resolver, String newAPN) {
Cursor cursor = null;
try {
//get new apn id from list
cursor = resolver.query(APN_LIST_URI, null, " apn = ? and current = 1", new String[]{newAPN.toLowerCase()}, null);
String apnId = null;
if (cursor != null && cursor.moveToFirst()) {
apnId = cursor.getString(cursor.getColumnIndex("_id"));
}
cursor.close();
//set new apn id as chosen one
if (apnId != null) {
ContentValues values = new ContentValues();
values.put("apn_id", apnId);
resolver.update(CURRENT_APN_URI, values, null, null);
} else {
//apn id not found, return 0.
return 0;
}
} catch (SQLException e) {
Debug.error(e.getMessage());
} finally {
if (cursor != null) {
cursor.close();
}
}
//update success
return 1;
}
在更改数据库之后，网络并不是立刻就能连接上的，我们需要加一个网络连接的消息监听器，发现切换成cmwap之后才开始连接服务器。NetworkChangeReceiver如下：
/*
* receiver for observing network connection change
*/
public class NetworkChangeReceiver extends BroadcastReceiver {
public void onReceive(Context context, Intent intent) {
if (ConnectivityManager.CONNECTIVITY_ACTION.equals(intent.getAction())) {
NetworkInfo info = conManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
String apn = info.getExtraInfo();
if ("cmwap".equals(apn)) {
/*
* apn change message is sent out more than once during a second, but it
* only happens once practically.
*/
if (mNChangeReceiver != null) {
updateDcdContent(mManRequest);
HwDcdCmService.this.unregisterReceiver(mNChangeReceiver);
mNChangeReceiver = null;
}
}
}
}
}
切换apn总入口如下，包括了检测当前apn, 切换，注册网络监听器：
/*
* change current network connection to cmwap if it's not.
*/
public int forceCMWapConnection() {
NetworkInfo info = conManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
oldAPN = info.getExtraInfo();
//if current apn is not cmwap, we have to switch to cmwap.
if (!"cmwap".equals(oldAPN)) {
mNChangeReceiver = new NetworkChangeReceiver();
//register receiver for wap network connection.
IntentFilter upIntentFilter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
registerReceiver(mNChangeReceiver, upIntentFilter);
MyUtil.updateCurrentAPN(getContentResolver(), "cmwap");
return 1;
}
return 0;
}
顺便值得一提的是，使用cmwap来连接网络的时候，仅仅切换接入点还不够，需要在请求头上加上http-route.default-proxy: 10.0.172:80. 代码如下：
HttpParams baseParams = new BasicHttpParams();
baseParams.setParameter("http.route.default-proxy",
new HttpHost(“10.0.0.172”, 80));
HttpConnectionParams.setConnectionTimeout(baseParams, 30 * 1000);
HttpConnectionParams.setSoTimeout(baseParams, 45 * 1000);
// establish HttpClient
DefaultHttpClient client = new DefaultHttpClient(baseParams);
备注：笔者发现ConnectionManager提供了一个conManager.startUsingNetworkFeature(type, value)，第一个设置为ConnectivityManager.TYPE_MOBILE， 第二个为”mms”的时候，也可以进行网络的切换，不涉及到setting里面的APN值的改变。第二个参数为APN接入点中的APN类型。但是这需要framework层的支持。中移动的Ophone sdk中可以使用这种方式来切换到cmwap或internet. 但是原版的android sdk中貌似不行。