import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.io.PrintWriter; import java.util.ArrayList; import java.util.Iterator; public class CountServlet extends HttpServlet { private static String htmlHead = ""; private static String htmlTail = ""; private static class CountInfo { String host; int port; int seqNo; CountInfo( String host, int port, int seqNo ) { this.host = host; this.port = port; this.seqNo = seqNo; } public String toString() { return host + ":" + port + " " + seqNo; } } private int count = 0; private ArrayList sites = new ArrayList(); private synchronized int nextCount() { return count++; } private synchronized void report( HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println( htmlHead ); out.println( "
    " ); Iterator it = sites.iterator(); while ( it.hasNext() ) { out.println( "
  1. " + it.next() + "
    2. " ); } out.println( "
" ); out.println( htmlTail ); } protected void doGet( HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String path = request.getPathInfo(); if ( path != null ) { if ( path.equals("/report") ) { report( request, response ); return; } } int seq = nextCount(); CountInfo info = new CountInfo( request.getRemoteHost(), request.getRemotePort(), seq ); synchronized( this ) { sites.add( info ); } response.setContentType("text/xml"); PrintWriter out = response.getWriter(); out.println( "" ); out.println( "" + seq + "" ); } }