获取网络信息，ip,子网掩码，网关，dns

无线网络信息可以通过api直接获取，无需特别处理，下面主要是机顶盒等android设备使用有线网络时网络信息的获取。

1.网络类型

/**
 * 获取网络类型
 * @return
 *      -1：未知网络
 *       0：无网络
 *       1：wifi网络
 *       2：移动网络
 *       3：以太网
 */
public static int getNetWorkInfo() {
    ConnectivityManager connectivityManager = (ConnectivityManager) MyApplication.getContext().getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo info = connectivityManager.getActiveNetworkInfo();
    if (info != null && info.isAvailable()) {
        if (info.getType() == ConnectivityManager.TYPE_WIFI) {
            return 1;
        }
        if (info.getType() == ConnectivityManager.TYPE_MOBILE) {
            return 2;
        }
        if (info.getType() == ConnectivityManager.TYPE_ETHERNET) {
            return 3;
        }
    } else {
        return 0;
    }
    return -1;
}

2.获取详细网络信息

static final String etName = "eth0";

@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private static NetWorkInfo getETnetwork(NetWorkInfo netWorkInfo) {
    EthernetManager mEthernetManager = (EthernetManager) MyApplication.getContext().getSystemService("ethernet");
    IpConfiguration configuration = mEthernetManager.getConfiguration();
    if (configuration == null) {
        return netWorkInfo;
    }
    IpConfiguration.IpAssignment ipAssignment = configuration.getIpAssignment();
    if (ipAssignment == null) {
        return netWorkInfo;
    }
    String ip = "";
    String mask = "";
    String gateway = "";
    String dns1 = "";
    String dns2 = "";
    if (IpConfiguration.IpAssignment.DHCP == ipAssignment) {//DHCP自动分配方式
        Log.i(TAG, "DHCP");
        ip = getSystemOsString("dhcp." + etName + ".ipaddress");//ip
        mask = getSystemOsString("dhcp." + etName + ".mask");
        gateway = getSystemOsString("dhcp." + etName + ".gateway");
        dns1 = getSystemOsString("dhcp." + etName + ".dns1");
        dns2 = getSystemOsString("dhcp." + etName + ".dns2");

    } else if (IpConfiguration.IpAssignment.STATIC == ipAssignment) {//手动设置方式
        Log.i(TAG, "STATIC");
        ip = configuration.getStaticIpConfiguration().ipAddress.getAddress().getHostAddress();
        mask = getMask(configuration.getStaticIpConfiguration().ipAddress.getPrefixLength());
        gateway = configuration.getStaticIpConfiguration().gateway.getHostAddress();
        dns1 = configuration.getStaticIpConfiguration().dnsServers.get(0).getHostAddress();
        dns2 = configuration.getStaticIpConfiguration().dnsServers.get(1).getHostAddress();
    }
    netWorkInfo.mask = mask;//子网掩码
    netWorkInfo.gateway = gateway;//网关
    netWorkInfo.dns1 = dns1;//dns1
    netWorkInfo.dns2 = dns2;//dns2
    return netWorkInfo;
}

/**
 * 计算子网掩码
 */
private static String getMask(int prefix) {
    StringBuilder stb = new StringBuilder();
    StringBuilder result = new StringBuilder();
    for (int i = 1; i <= 32; i++) {
        stb.append(i <= prefix ? "1" : "0");
        if (i % 8 == 0) {
            result.append(Integer.parseInt(stb.toString(), 2)).append(".");
            stb.setLength(0);
        }
    }
    return result.deleteCharAt(result.length() - 1).toString();
}

关于子网掩码的计算：
prefixLength最大32位，可以分成4组8个1的二进制，正好是255，255，255，255，少N位就要在末尾去掉N个1加上N个0，然后再把4组二进制数据换成十进制就得出最终结果；
例如：
30 = 255，255，255，252
26 = 255，255，255，192
最后，EthernetManager这个类是被隐藏的，可以自己把这一部分的android源码加到自己的项目里去调用，也可以用我上传的jar包直接用。
android.net.jar