我正在尝试使用Android应用程序ping我的服务器，并且服务器返回其IP地址。
到目前为止，我已经与服务器和服务器进行通信以发回数据包，但是，我需要重新发送服务器IP地址。
UDPService.java（服务器）
package mySystem.server;
import java.net.*;
public class UDPService implements Runnable {
public static void main(String args[]) {
}
@Override
public void run() {
System.out.println("Starting");
try {
int port = 1989;
// Create a socket to listen on the port.
DatagramSocket dsocket = new DatagramSocket(port);
// Create a buffer to read datagrams into. If a
// packet is larger than this buffer, the
// excess will simply be discarded!
byte[] receiveData = new byte[1024];
byte[] sendData = new byte[1024];
// Create a packet to receive data into the buffer
DatagramPacket packet = new DatagramPacket(receiveData, receiveData.length);
System.out.println("loop start");
// Now loop forever, waiting to receive packets and printing them.
while (true) {
// Wait to receive a datagram
System.out.println("receive packet");
dsocket.receive(packet);
System.out.println("populate sentence");
String sentence = new String(packet.getData());
System.out.println("RECEIVED: " + sentence);
// Convert the contents to a string, and display them
System.out.println("send packet");
dsocket.send(packet);
// Reset the length of the packet before reusing it.
System.out.println("setlength");
packet.setLength(receiveData.length);
}
} catch (Exception e) {
System.err.println(e);
}
}
}
Discoverer.java（电话应用）
package com.krathsilvercloud.app;
import java.net.*;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketTimeoutException;
import java.net.UnknownHostException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import android.net.DhcpInfo;
import android.net.wifi.WifiManager;
import android.util.Log;
import android.util.Log;
import android.widget.Toast;
public class Discoverer extends Thread {
private static final String TAG = "Discovery";
private static final String REMOTE_KEY = "b0xeeRem0tE!";
private static final int DISCOVERY_PORT = 1989;
private static final int TIMEOUT_MS = 5000;
private InetAddress addr;
private static final String mChallenge = "wuffwuff";
private WifiManager mWifi;
interface DiscoveryReceiver {
void addAnnouncedServers(InetAddress[] host, int port[]);
}
Discoverer(WifiManager wifi) {
mWifi = wifi;
try {
addr = getBroadcastAddress();
} catch (IOException e) {
Log.e(TAG, "Could not get bind address", e);
}
}
public String DiscoverRun() {
try {
DatagramSocket socket = new DatagramSocket(DISCOVERY_PORT);
socket.setBroadcast(true);
socket.setSoTimeout(TIMEOUT_MS);
sendDiscoveryRequest(socket);
return listenForResponses(socket);
} catch (IOException e) {
Log.e(TAG, "Could not send discovery request", e);
return null;
}
}
private void sendDiscoveryRequest(DatagramSocket socket) throws IOException {
String data = String.format(mChallenge);
Log.d(TAG, "Sending data " + data);
DatagramPacket packet = new DatagramPacket(data.getBytes(), data.length(),
addr, DISCOVERY_PORT);
socket.send(packet);
}
private InetAddress getBroadcastAddress() throws IOException {
DhcpInfo dhcp = mWifi.getDhcpInfo();
if (dhcp == null) {
Log.d(TAG, "Could not get dhcp info");
return null;
}
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 String listenForResponses(DatagramSocket socket) throws IOException {
byte[] buf = new byte[1024];
try {
while (true) {
DatagramPacket packet = new DatagramPacket(buf, buf.length);
socket.receive(packet);
Log.d(TAG, packet.getAddress().getHostAddress());
String s = new String(packet.getData(), 0, packet.getLength());
Log.d(TAG, "Received response " + s);
String IPAddress2 = new String(packet.getAddress().getHostAddress());
return IPAddress2;
}
} catch (SocketTimeoutException e) {
Log.d(TAG, "Receive timed out");
return null;
}
}
private String getSignature(String challenge) {
MessageDigest digest;
byte[] md5sum = null;
try {
digest = java.security.MessageDigest.getInstance("MD5");
digest.update(challenge.getBytes());
digest.update(REMOTE_KEY.getBytes());
md5sum = digest.digest();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
StringBuffer hexString = new StringBuffer();
for (int k = 0; k < md5sum.length; ++k) {
String s = Integer.toHexString((int) md5sum[k] & 0xFF);
if (s.length() == 1)
hexString.append('0');
hexString.append(s);
}
return hexString.toString();
}
public static void main(String[] args) {
new Discoverer(null).start();
while (true) {
}
}
}
search.java（电话应用）
Button Submit = (Button) findViewById(R.id.SearchBtn);
Submit.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
Socket socket;
PrintWriter out;
BufferedReader in;
String Results;
String SearchStr = ((EditText) findViewById(R.id.SearchEntryTxt)).getText().toString().trim();
String AndroidID = Secure.getString(getBaseContext().getContentResolver(), Secure.ANDROID_ID);
dis = new Discoverer((WifiManager)getSystemService(WIFI_SERVICE));
IPAddress = dis.DiscoverRun();
Toast toast = Toast.makeText(getApplicationContext(), "IP Address: >" + IPAddress + "<", 2000);
toast.show();
此后有相当多的代码，但它只是基于IPAddress为空时会发生什么的if语句