android - Android手动开启3G连接，并保持开启

Question

如何在打开WiFi的同时在Android中启动3G数据连接？我试过了

IConnectivityManager.setMobileDataEnabled(enabled); // via reflection

它在模拟器中工作，但在我的真实手机 (Droid 2) 中，它会短暂打开然后再次关闭。

来自 shell (adb shell)，ip link提供 3G 连接的详细信息:

15: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 3 link/ppp

但是，它仅在 WiFi 关闭时可用。当 WiFi 打开并且我尝试手动打开它时，它会提示 ppp0 设备不存在。

bash-3.2# ip link set ppp0 up
ip link set ppp0 up
Cannot find device "ppp0"

当我尝试列出设备时，我什至找不到它

bash-3.2# ls /dev/ppp*
ls /dev/ppp*
/dev/ppp

Answer 1

据我了解，如果不修改 Android 平台源代码(至少版本 2.3 和 4)，则不可能同时连接 3g 和 WiFi。主要问题是 frameworks/base/core/res/res/values/config.xml 中定义的硬编码连接优先级:

<!-- This string array should be overridden by the device to present a list of network
attributes. This is used by the connectivity manager to decide which networks can coexist
based on the hardware -->
    <!-- An Array of "[Connection name],[ConnectivityManager connection type],
[associated radio-type],[priority] -->
 <!--                   ^^^^^^^^^^---------- Connection priority -->

    <string-array translatable="false" name="networkAttributes">
        <item>"wifi,1,1,1"</item>
        <item>"mobile,0,0,0"</item>
        <item>"mobile_mms,2,0,2"</item>
        <item>"mobile_supl,3,0,2"</item>
        <item>"mobile_hipri,5,0,3"</item>
    </string-array>

此 config.xml 然后由 ConnectivityService 读取它订阅了连接/断开连接事件。在连接处理程序中，它决定应该如何处理其他连接:

private void handleConnect(NetworkInfo info) {

        //------------8-<--------------------------

        // if this is a default net and other default is running
        // kill the one not preferred
        if (mNetAttributes[type].isDefault()) {
            if (mActiveDefaultNetwork != -1 && mActiveDefaultNetwork != type) {
                if ((type != mNetworkPreference &&
                        mNetAttributes[mActiveDefaultNetwork].mPriority >
                        //                                    ^^^^^^^^^ --- From config.xml
                        mNetAttributes[type].mPriority) ||
                        //                   ^^^^^^^^^-------- From config.xml
                        mNetworkPreference == mActiveDefaultNetwork) {
                        // don't accept this one
                        if (DBG) Slog.v(TAG, "Not broadcasting CONNECT_ACTION " +
                                "to torn down network " + info.getTypeName());
                        teardown(thisNet);
                        return;
          //------------8-<--------------------------