java web 利用filter 防止 Xss 攻击（1）

<!--@分隔 -->
    <filter>
        <filter-name>xssFilter</filter-name>
        <filter-class>com.yoro.core.web.XssFilter</filter-class>
        <init-param>
            <param-name>SplitChar</param-name>
            <param-value>@</param-value>
        </init-param>
        <init-param>
            <param-name>FilterChar</param-name>
            <param-value>>@<@\'@\"@\\@#@(@)</param-value>//但大于号在xml不行，需要注意
        </init-param>
        <init-param>
            <param-name>ReplaceChar</param-name>
            <param-value>＞'@＜@‘@“@＼@＃@（@）</param-value>
        </init-param>
    </filter>

 <filter-mapping>

        <filter-name>xssFilter</filter-name>

  <url-pattern>/*</url-pattern>

    </filter-mapping>

package com.yoro.core.web;

/**
 * @author zoro
 */
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;

public class XssFilter implements Filter {

    private String filterChar;
    private String replaceChar;
    private String splitChar;
    FilterConfig filterConfig = null;
    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterChar=filterConfig.getInitParameter("FilterChar");
        this.replaceChar=filterConfig.getInitParameter("ReplaceChar");
        this.splitChar=filterConfig.getInitParameter("SplitChar");
        this.filterConfig = filterConfig;
    }

    public void destroy() {
        this.filterConfig = null;
    }

    public void doFilter(ServletRequest request, ServletResponse response,

    FilterChain chain) throws IOException, ServletException {
        chain.doFilter(new XssHttpServletRequestWrapper((HttpServletRequest) request,filterChar,replaceChar,splitChar), response);
    }
}

package com.yoro.core.web;



import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;

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


/**
 * @author zoro
 */
public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
    private String[]filterChars;
    private String[]replaceChars;
    public XssHttpServletRequestWrapper(HttpServletRequest request,String filterChar,String replaceChar,String splitChar) {
        super(request);
        if(filterChar!=null&&filterChar.length()>0){
            filterChars=filterChar.split(splitChar);
        }
        if(replaceChar!=null&&replaceChar.length()>0){
            replaceChars=replaceChar.split(splitChar);
        }
    }
    public String getQueryString() {
        String value = super.getQueryString();
        if (value != null) {
            value = xssEncode(value);
        }
        return value;
    }

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

    public String[] getParameterValues(String name) {
        String[]parameters=super.getParameterValues(name);
        if (parameters==null||parameters.length == 0) {
            return null;
        }
        for (int i = 0; i < parameters.length; i++) {
            parameters[i] = xssEncode(parameters[i]);
        }
        return parameters;
    }

    /**
     * 覆盖getHeader方法，将参数名和参数值都做xss过滤。<br/>
     * 如果需要获得原始的值，则通过super.getHeaders(name)来获取<br/> getHeaderNames 也可能需要覆盖
     */
    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  String xssEncode(String s) {
        if (s == null || s.equals("")) {
            return s;
        }
        try {
            s = URLDecoder.decode(s, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        for (int i = 0; i < filterChars.length; i++) {
            if(s.contains(filterChars[i])){
                s=s.replace(filterChars[i], replaceChars[i]);
            }
        }
        return s;
    }
}