在Android 5 (L)上以编程方式更改WiFi配置

Question

在Android 5 (L)上以编程方式更改WiFi配置

6

在Android 4.0.2..4.4.4上工作的代码存在一些问题，但在Android 5上并没有真正起作用，我不知道为什么。基本上，以下代码允许设置新的WiFi IP分配类型：STATIC或DHCP。我使用的代码完全涵盖在这个答案中：https://dev59.com/mGkv5IYBdhLWcg3w40wY#10309323

我将尝试在此处放置代码的最重要部分和输出信息。

...
WifiConfigurator.setIpAssignment("STATIC", wifiConf);
...

其中wifiConf是

public static WifiConfiguration getCurrentWiFiConfiguration(Context context) {
    WifiConfiguration wifiConf = null;
    ConnectivityManager connManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
    if (networkInfo.isConnected()) {
        final WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
        final WifiInfo connectionInfo = wifiManager.getConnectionInfo();
        if (connectionInfo != null && !TextUtils.isEmpty(connectionInfo.getSSID())) {
            List<WifiConfiguration> configuredNetworks = wifiManager.getConfiguredNetworks();
            if(configuredNetworks != null){
                for (WifiConfiguration conf : configuredNetworks) {
                    if (conf.networkId == connectionInfo.getNetworkId()) {
                        wifiConf = conf;
                        break;
                    }
                }
            }
        }
    }
    return wifiConf;
}

所以WifiConfigurator.setIpAssigment()调用了以下代码：

public static void setIpAssignment(String assign, WifiConfiguration wifiConf)
        throws SecurityException, IllegalArgumentException, NoSuchFieldException, IllegalAccessException {

    setEnumField(wifiConf, assign, "ipAssignment");
}

public static void setEnumField(Object obj, String value, String name)
        throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
    Log.d("myApp", obj.getClass().toString());
    Field f = obj.getClass().getField(name);
    f.set(obj, Enum.valueOf((Class<Enum>) f.getType(), value));
}

但是由于某些原因，无法找到“ipAssignment”字段：

11-30 12:40:54.343    5941-5941/com.myApp D/myApp﹕ class android.net.wifi.WifiConfiguration
11-30 12:40:54.344    5941-5941/com.myApp D/myApp﹕ Can't update network configuration. java.lang.NoSuchFieldException: ipAssignment
            at java.lang.Class.getField(Class.java:1048)
            at com.myApp.WifiConfigurator.setEnumField(WifiConfigurator.java:141)
            at com.myApp.WifiConfigurator.setIpAssignment(WifiConfigurator.java:25)
            at com.myApp.WifiConfigurator.updateWifiNetwork(WifiConfigurator.java:220)
            at com.myApp.ui.MainScreen.onAsyncTaskCompleted(MainScreen.java:251)
            at com.myApp.myAPI$UpdateIPTask.onPostExecute(myAPI.java:257)
            at com.myApp.myAPI$UpdateIPTask.onPostExecute(myAPI.java:194)
            at android.os.AsyncTask.finish(AsyncTask.java:632)
            at android.os.AsyncTask.access$600(AsyncTask.java:177)
            at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

起初，我认为谷歌改变了该字段的名称。然后我检查了Android L预览源代码，发现该字段确实存在。我不明白为什么会出现这种情况。

更新：

感谢Matiash提供的一些信息，我能够更新ipAssignment类型，但我无法更新DNS。要更新DNS，ipAssigment应该是静态的。根据这个，谷歌停止使用LinkProperties进行静态配置，现在使用StaticIpConfiguration类。

所以我该怎么做：

public static void setDNS(InetAddress dns1, InetAddress dns2, WifiConfiguration wifiConf)
        throws SecurityException, IllegalArgumentException, NoSuchMethodException, InvocationTargetException,
        NoSuchFieldException, IllegalAccessException {

    Object linkProperties = null;
    ArrayList<InetAddress> mDnses;

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        staticIpConf = wifiConf.getClass().getMethod("getStaticIpConfiguration").invoke(wifiConf);
        mDnses = (ArrayList<InetAddress>) getDeclaredField(staticIpConf, "dnsServers");
    }
    else{
        linkProperties = getField(wifiConf, "linkProperties");
        mDnses = (ArrayList<InetAddress>) getDeclaredField(linkProperties, "mDnses");
    }

    mDnses.clear();
    mDnses.add(dns1);
    mDnses.add(dns2);
}
public static Object getDeclaredField(Object obj, String name)
        throws SecurityException, NoSuchFieldException,
        IllegalArgumentException, IllegalAccessException {

    Field f = obj.getClass().getDeclaredField(name);
    f.setAccessible(true);
    Object out = f.get(obj);
    return out;
}

下一步我在错误日志中看到的是:

12-22 09:00:49.854  25815-25815/com.myapp D/myapp﹕ Can't update network configuration. java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
            at com.myapp.WifiConfigurator.getDeclaredField(WifiConfigurator.java:245)
            at com.myapp.WifiConfigurator.setDNS(WifiConfigurator.java:78)
            at com.myapp.WifiConfigurator.updateWifiNetwork(WifiConfigurator.java:356)

我的猜测是在调用staticIpConfiguration时它不存在。我必须以某种方式初始化它。有什么想法如何更新DNS？

- KennyPowers

为了确保你正在查看正确的源代码，也许你可以尝试在一个快速测试中读取该类中的所有字段，并查看它具有哪些字段。 - Ingo Bürk

1个回答

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可以查看英文原文，
原文链接

- matiash · Accepted Answer

尽管在L版本（至少在grepcode中的版本）中仍然存在 ipAssignment 字段，但在发布版本中已经不存在，您可以在源代码的“master”分支或Github镜像中看到。

枚举定义和字段现在都在一个内部对象 IpConfiguration （也是新的）中。这就是使用反射访问未记录水域的危险所在... :)

但是，将代码进行微调以通过反射访问并在那里设置它非常简单：

public static void setIpAssignment(String assign, WifiConfiguration wifiConf)
        throws SecurityException, IllegalArgumentException, NoSuchFieldException, IllegalAccessException, InvocationTargetException, NoSuchMethodException {

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        Object ipConfiguration = wifiConf.getClass().getMethod("getIpConfiguration").invoke(wifiConf);
        setEnumField(ipConfiguration, assign, "ipAssignment");
    } else {
        setEnumField(wifiConf, assign, "ipAssignment");
    }
}

这段代码“有效”（在不抛出异常的情况下），但我没有进一步测试它。

< p >< em >请参阅如何为Android 5.x（Lollipop）为WiFi连接以编程方式配置静态IP地址、子网掩码、网关和DNS，以获取更详细的解决方案。