Java防止xss攻击

首先说一下思路，防止这种类似于注入攻击，就是使用拦截器（Filter）处理特殊字符或过滤特殊字符

今天介绍一个方法，利用覆盖Servlet的getParameter方法达到处理特殊字符的目的来解决（防止）Xss攻击

web.xml

<filter> 
 <filter-name>XssEscape</filter-name> 
 <filter-class>www.ablanxue.com.filter.XssFilter</filter-class> 
</filter> 
<filter-mapping> 
 <filter-name>XssEscape</filter-name> 
 <url-pattern>/*</url-pattern> 
 <dispatcher>REQUEST</dispatcher> 
</filter-mapping>

Filter类（XssFilter.   Jav a  ）

package www.ablanxue.com.filter;

import java.io.IOException;

import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

public class XssFilter implements javax.servlet.Filter {

 @Override
 public void destroy() {
 // TODO Auto-generated method stub
 
 }

 @Override
 public void doFilter(ServletRequest request, ServletResponse response,
 FilterChain filterChain) throws IOException, ServletException {
 
 XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request);
 filterChain.doFilter(xssRequest, response);
 }

 @Override
 public void init(FilterConfig arg0) throws ServletException {
 // TODO Auto-generated method stub
 
 }

}

最关键的类（XssHttpServletRequestWrapper.java）

继承servlet的HttpServletRequestWrapper，并重写相应的几个有可能带xss攻击的方法

package www.ablanxue.com.filter;

import java.io.StringReader;
import java.io.StringWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import com.blogspot.radialmind.html.HTMLParser;
import com.blogspot.radialmind.xss.XSSFilter;

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
 
 HttpServletRequest orgRequest = null;

 public XssHttpServletRequestWrapper(HttpServletRequest request) {
 super(request);
 orgRequest = request;
 }

 /**
 * 覆盖getParameter方法，将参数名和参数值都做xss过滤。
 * 如果需要获得原始的值，则通过super.getParameterValues(name)来获取
 * getParameterNames,getParameterValues和getParameterMap也可能需要覆盖
 */
 @Override
 public String getParameter(String name) {
 String value = super.getParameter(xssEncode(name));
 if (value != null) {
 value = xssEncode(value);
 }
 return value;
 }

 /**
 * 覆盖getHeader方法，将参数名和参数值都做xss过滤。
 * 如果需要获得原始的值，则通过super.getHeaders(name)来获取
 * getHeaderNames 也可能需要覆盖
 */
 @Override
 public String getHeader(String name) {

 String value = super.getHeader(xssEncode(name));
 if (value != null) {
 value = xssEncode(value);
 }
 return value;
 }

 /**
 * 将容易引起xss漏洞的半角字符直接替换成全角字符
 * 
 * @param s
 * @return
 */
 private static String xssEncode(String s) {
 
 
 if (s == null || s.isEmpty()) {
 return s;
 }

 StringReader reader = new StringReader(s);
 StringWriter writer = new StringWriter();
 try {
 HTMLParser.process(reader, writer, new XSSFilter(), true);

 
 String result = writer.toString();
 
 System.out.println("xssEncode-------------------------" + s + " = " + result);
 
 return result;
 } catch (NullPointerException e) {
 return s;
 } catch (Exception ex) {
 ex.printStackTrace();
 }

 return null;

 }

 /**
 * 获取最原始的request
 * 
 * @return
 */
 public HttpServletRequest getOrgRequest() {
 return orgRequest;
 }

 /**
 * 获取最原始的request的静态方法
 * 
 * @return
 */
 public static HttpServletRequest getOrgRequest(HttpServletRequest req) {
 if (req instanceof XssHttpServletRequestWrapper) {
 return ((XssHttpServletRequestWrapper) req).getOrgRequest();
 }

 return req;
 }
}

 
 

  
  
依赖jar包
  
  
百度网盘下载
  
  
xssProtect-0.1.jar
  
  
antlr-runtime-3.0.1.jar
  
  


 
 
转载注明本文地址：http://www.ablanxue.com/shtml/201502/26346_1.shtml

通过重写getParameter()等方法，实现简单的过滤，从而防止Xss攻击