[Android]获取局域网广播地址的两种方法

[Android]获取局域网广播地址的两种方法

private InetAddress calcBroadcastAddress(InetAddress mask, InetAddress ip)
throws IOException {
int ipaddress = getIntAddress(ip);
int maskaddress = getIntAddress(mask);
int broadcast = ipaddress & maskaddress | ~maskaddress;
byte[] quads = new byte[4];
for (int k = 0; k < 4; k++) {
quads[k] = (byte) ((broadcast >> k * 8) & 0xFF);
}
return InetAddress.getByAddress(quads);
}

private InetAddress getBroadcastAddress() throws IOException {
// 自动获取
String strIp = getCommandResult("/system/bin/getprop",
"dhcp.eth0.ipaddress");
String strMask = getCommandResult("/system/bin/getprop",
"dhcp.eth0.mask");
if (!strIp.equals("\n")) {
InetAddress mask = InetAddress.getByName(strMask);
InetAddress ip = InetAddress.getByName(strIp);
Log.v("ws-discovery", "auto ip:" + strIp);
return calcBroadcastAddress(mask, ip);

} else {
// 手动配置
String strManual = getCommandResult("/system/bin/ifconfig", "eth0");
String[] netInfo = strManual.split(" ");
if (netInfo.length >= 5) {
InetAddress mask = InetAddress.getByName(netInfo[4]);
InetAddress ip = InetAddress.getByName(netInfo[2]);
Log.v("ws-discovery", "manual ip:" + netInfo[2]);
return calcBroadcastAddress(mask, ip);
}
}
// wifi
WifiManager wifi = (WifiManager) mContext
.getSystemService(Context.WIFI_SERVICE);
DhcpInfo dhcp = wifi.getDhcpInfo();
Log.v("ws-discovery", "wifi ip:" + Integer.toString(dhcp.ipAddress));
int broadcast = (dhcp.ipAddress & dhcp.netmask) | ~dhcp.netmask;
byte[] quads = new byte[4];
for (int k = 0; k < 4; k++) {
quads[k] = (byte) ((broadcast >> k * 8) & 0xFF);
}
return InetAddress.getByAddress(quads);
}
private int getIntAddress(InetAddress address) {
byte[] addrs = address.getAddress();
int addr = 0;
addr = ((addrs[3] & 0xff) << 24) | ((addrs[2] & 0xff) << 16)
| ((addrs[1] & 0xff) << 8) | (addrs[0] & 0xff);
return addr;
}

private String getCommandResult(String commands, String args) {
Process process = null;
String inet = null;
try {
process = new ProcessBuilder().command(commands, args)
.redirectErrorStream(true).start();
InputStream in = process.getInputStream();
int count = 0;
while (count == 0) {
count = in.available();
}
byte[] b = new byte[count];
in.read(b);
inet = new String(b);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (process != null)
process.destroy();
}
return inet;
}

public static String getBroadcast() throws SocketException {
System.setProperty("java.net.preferIPv4Stack", "true");
for (Enumeration<NetworkInterface> niEnum = NetworkInterface.getNetworkInterfaces(); niEnum.hasMoreElements();) {
NetworkInterface ni = niEnum.nextElement();
if (!ni.isLoopback()) {
for (InterfaceAddress interfaceAddress : ni.getInterfaceAddresses()) {
if (interfaceAddress.getBroadcast() != null) {
return interfaceAddress.getBroadcast().toString().substring(1);
}
}
}
}
return null;
}