import Java.io.IOException;
import java.util.StringTokenizer;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;
public class IPFilter implements Filter {
private FilterConfig config;
public final static String IP_RANGE = "192.168";
public IPFilter() {
}
public void init(FilterConfig filterConfig) throws ServletException {
this.config = filterConfig;
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
String ip = request.getRemoteAddr();
HttpServletResponse httpResp = null;
if (response instanceof HttpServletResponse)
httpResp = (HttpServletResponse) response;
StringTokenizer toke = new StringTokenizer(ip, ".");
int dots = 0;
String byte1 = "";
String byte2 = "";
String client = "";
while (toke.hasMoreTokens()) {
++dots;
//if we've reached the second dot, break and check out the indx
// value
if (dots == 1) {
byte1 = toke.nextToken();
} else {
byte2 = toke.nextToken();
break;
}
}//while
//Piece together half of the client IP address so it can be compared
// with
//the forbidden range represented by IPFilter.IP_RANGE
client = byte1 + "." + byte2;
if (IP_RANGE.equals(client)) {
httpResp.sendError(HttpServletResponse.SC_FORBIDDEN,
"That means goodbye forever!");
} else {
chain.doFilter(request, response);
}
}// doFilter
public void destroy() {
/*
* called before the Filter instance is removed from service by the web
* container
*/
}
}
（出处：http://www.knowsky.com）