Go语言视频零基础入门到精通

javalearner

1. import java.io.IOException;
   
2. import java.util.StringTokenizer;
   
3. import javax.servlet.Filter;
   
4. import javax.servlet.FilterChain;
   
5. import javax.servlet.FilterConfig;
   
6. import javax.servlet.ServletException;
   
7. import javax.servlet.ServletRequest;
   
8. import javax.servlet.ServletResponse;
   
9. import javax.servlet.http.HttpServletResponse;
   
10. public class IPFilter implements Filter {
    
11.   private FilterConfig config;
    
12.   public final static String IP_RANGE = "192.168";
    
13.   public IPFilter() {
    
14.   }
    
15.   public void init(FilterConfig filterConfig) throws ServletException {
    
16.     this.config = filterConfig;
    
17.   }
    
18.   public void doFilter(ServletRequest request, ServletResponse response,
    
19.       FilterChain chain) throws IOException, ServletException {
    
20.     String ip = request.getRemoteAddr();
    
21.     HttpServletResponse httpResp = null;
    
22.     if (response instanceof HttpServletResponse)
    
23.       httpResp = (HttpServletResponse) response;
    
24.     StringTokenizer toke = new StringTokenizer(ip, ".");
    
25.     int dots = 0;
    
26.     String byte1 = "";
    
27.     String byte2 = "";
    
28.     String client = "";
    
29.     while (toke.hasMoreTokens()) {
    
30.       ++dots;
    
31.       //if we"ve reached the second dot, break and check out the indx
    
32.       // value
    
33.       if (dots == 1) {
    
34.         byte1 = toke.nextToken();
    
35.       } else {
    
36.         byte2 = toke.nextToken();
    
37.         break;
    
38.       }
    
39.     }//while
    
40.     //Piece together half of the client IP address so it can be compared
    
41.     // with
    
42.     //the forbidden range represented by IPFilter.IP_RANGE
    
43.     client = byte1 + "." + byte2;
    
44.     if (IP_RANGE.equals(client)) {
    
45.       httpResp.sendError(HttpServletResponse.SC_FORBIDDEN,
    
46.           "That means goodbye forever!");
    
47.     } else {
    
48.       chain.doFilter(request, response);
    
49.     }
    
50.   }// doFilter
    
51.   public void destroy() {
    
52.     /*
    
53.      * called before the Filter instance is removed from service by the web
    
54.      * container
    
55.      */
    
56.   }
    
57. }

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