统计局域网内在线机子的数量，并将这些在线机子的IP输入到数据库！之后检测这些在线IP是否提供web服务或ftp服务。
解决思路：用 ping 协议穷举，然后socket探测其 80 和 25 端口是否开放。
public class Test {
public static void main(String[] args) {
int ips[] = new int[] { 192, 168, 43, 0 };
for(int i = 1; i < 255; i++) {
String ip = ips[0] + "." + ips[1] + "." + ips[2] + "." + i;
//System.out.println("start：" + ip);
while(!runPT(ip)) {
try {
Thread.sleep(10);
} catch (InterruptedException e) {
}
}
}
}
public static class PingThread extends Thread {
private String ip;
private boolean running;
public String getIp() {
return ip;
}
public void setIp(String ip) {
this.ip = ip;
}
public boolean isRunning() {
return running;
}
public void setRunning(boolean running) {
this.running = running;
}
@Override
public void run() {
while (true) {
synchronized (this) {
// running = true;
try {
if(ip != null) {
//linux
//String cmd = "ping -c 4 " + ip;
//windows
String cmd = "ping -n 4 " + ip;
String key = "TTL";
//System.out.println(cmd);
boolean pingok = false;
java.lang.Process p = java.lang.Runtime.getRuntime().exec(cmd);
java.io.InputStream is = p.getInputStream();
java.io.BufferedReader br = new java.io.BufferedReader(new java.io.InputStreamReader(is));
String line;
int linenum=0;
while(null != (line = br.readLine())) {
linenum++;
if(line.contains(key)) {
pingok = true;
//System.out.println(linenum+" : "+line);
break;
}
if(linenum>2){
break;
}
}
p.destroy();
if(pingok) {
System.out.println("ping " + ip + " is ok...");
for(int i = 1; i < 255; i++) {
while(!runCT(ip, i)) {
try{
Thread.sleep(10);
} catch(Exception e) {
}
}
}
}else{
//System.out.println("Unknow host "+ip);
}
}
} catch(Exception e) {
} finally {
this.ip = null;
running = false;
try{
this.wait();
} catch(Exception e) {
}
}
}
}
}
}
public static class ConnectThread extends Thread {
private String host;
private int port;
private boolean running;
public boolean isRunning() {
return running;
}
public String getHost() {
return host;
}
public void setHost(String host) {
this.host = host;
}
public int getPort() {
return port;
}
public void setPort(int port) {
this.port = port;
}
public void setRunning(boolean running) {
this.running = running;
}
@Override
public void run() {
while(true){
//System.out.println("is opened");
synchronized(this) {
running = true;
try {
if(host != null) {
java.net.Socket s = new java.net.Socket(this.host, this.port);
s.close();
System.out.println("Host " + this.host + " port " + this.port + " is opened");
}
} catch(Exception e) {
} finally {
running = false;
this.host = null;
try {
this.wait();
} catch(Exception e) {
}
}
}
}
}
}
private static final Object ct_locker = new Object();
private static java.util.List<ConnectThread> ct_pool = new java.util.ArrayList<ConnectThread>();
private static int ct_pool_limit = 500;
public static boolean runCT(String host, int port) {
synchronized(ct_locker){
ConnectThread ct = null;
for(int i = 0; i < ct_pool.size(); i++) {
if(!ct_pool.get(i).isRunning()){
ct = ct_pool.get(i);
ct.setHost(host);
ct.setPort(port);
synchronized(ct) {
ct.notify();
}
break;
}
}
if(ct == null && ct_pool.size() < ct_pool_limit) {
ct = new ConnectThread();
ct.setHost(host);
ct.setPort(port);
ct.start();
ct_pool.add(ct);
}
if(ct != null) {
return true;
} else {
return false;
}
}
}
private static final Object pt_locker = new Object();
private static java.util.List<PingThread> pt_pool = new java.util.ArrayList<PingThread>();
private static int pt_pool_limit = 500;
public static boolean runPT(String ip) {
synchronized(pt_locker) {
boolean ret = false;
PingThread pt = null;
for(int i = 0; i < pt_pool.size(); i++) {
if(!pt_pool.get(i).isRunning()) {
pt = pt_pool.get(i);
pt.setIp(ip);
synchronized(pt) {
pt.setRunning(true);
pt.notify();
}
break;
}
}
if(pt == null && pt_pool.size() < pt_pool_limit) {
pt = new PingThread();
pt.setIp(ip);
pt.start();
pt.setRunning(true);
pt_pool.add(pt);
}
if(pt != null) {
ret = true;
}
return ret;
}
}
}