使用HttpServletRequestWrapper 实现防止xss攻击和sql注入

XSS(Cross Site Scripting)，即跨站脚本攻击，是一种常见于web application中的计算机安全漏洞。XSS通过在用户端注入恶意的可运行脚本，若服务器端对用户输入不进行处理，直接将用户输入输出到浏览器，则浏览器将会执行用户注入的脚本。

使用filter实现xss的攻击：

1：自定义一个wapper 实现 HttpServletRequestWrapper

package com.filter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

/**
 * xss过滤
 */
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 || "".equals(s)) {
            return s;
        }
        StringBuilder sb = new StringBuilder(s.length() + 16);
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            switch (c) {
                case '>':
                    sb.append('＞');//全角大于号
                    break;
                case '<':
                    sb.append('＜');//全角小于号
                    break;
                case '\'':
                    sb.append('‘');//全角单引号
                    break;
                case '\"':
                    sb.append('“');//全角双引号
                    break;
                case '&':
                    sb.append('＆');//全角
                    break;
                case '\\':
                    sb.append('＼');//全角斜线
                    break;
                case '#':
                    sb.append('＃');//全角井号
                    break;
                default:
                    sb.append(c);
                    break;
            }
        }
        return sb.toString();
    }

    /**
    * 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;
    }

    public static void main(String[] args) {
        System.out.println(XssHttpServletRequestWrapper.xssEncode(""));
    }
}

2: 自定义过滤器

package com.filter;

import java.io.IOException;

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.HttpServletRequest;

/**
 *
 * 拦截防止sql注入、xss注入 
 */
public class XssFilter implements Filter {

    /* (non-Javadoc)
     * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
     */
    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 destroy() {

    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {

    }

}

3: web.xml中配置filter

  
    XssFilter  
    com.filter  
  
  
    XssFilter  
    /*