利用Filter实现IP过滤

　2007-12-23 12:35:42　来源：WEB开发网　闂傚倷绶氬ḿ褍螞閹绢喖绠柨鐕傛嫹

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核心提示：import java.io.IOException;import java.util.StringTokenizer;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;impor

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
　　 */
　}

}

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