android WifiMange获取IP为负

通过WifiMange获得ip步骤如下：

WifiManager wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);  WifiInfo wifiInfo = wifiManager.getConnectionInfo();       int ipAddress = wifiInfo.getIpAddress();   String ip = String.format("%d.%d.%d.%d", (ipAddress & 0xff), (ipAddress >> 8 & 0xff), (ipAddress >> 16 & 0xff), (ipAddress >> 24 & 0xff));

目前还不清楚什么原因，某些设备获取wifiInfo.getIpAddress()返回值是个负数值；

所以查看android源码【AbstractIpAddressPreferenceController.java】

  @Override    protected void updateConnectivity() {        String ipAddress = getDefaultIpAddresses(mCM);        if (ipAddress != null) {            mIpAddress.setSummary(ipAddress);        } else {            mIpAddress.setSummary(R.string.status_unavailable);        }    }    /**     * Returns the default link's IP addresses, if any, taking into account IPv4 and IPv6     style     * addresses.     * @param cm ConnectivityManager     * @return the formatted and newline-separated IP addresses, or null if none.     */    private static String getDefaultIpAddresses(ConnectivityManager cm) {        LinkProperties prop = cm.getActiveLinkProperties();        return formatIpAddresses(prop);    }    private static String formatIpAddresses(LinkProperties prop) {        if (prop == null) return null;        Iterator iter = prop.getAllAddresses().iterator();        // If there are no entries, return null        if (!iter.hasNext()) return null;        // Concatenate all available addresses, newline separated        StringBuilder addresses = new StringBuilder();        while (iter.hasNext()) {            addresses.append(iter.next().getHostAddress());            if (iter.hasNext()) addresses.append("\n");        }        return addresses.toString();    }

可以看到，系统源码是用ConnectivityManager 方法获取，从中提取后方法如下：

ConnectivityManager conMann =(ConnectivityManager)this.getSystemService(Context.CONNECTIVITY_SERVICE);            NetworkInfo mobileNetworkInfo = conMann.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);            NetworkInfo wifiNetworkInfo = conMann.getNetworkInfo(ConnectivityManager.TYPE_WIFI);if (mobileNetworkInfo.isConnected()) {    System.out.println("ip ==== " + getLocalIpAddress());}

经过测试，可以获得正确IP地址；

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