java web 利用filter 防止 Xss 攻击

	<!--@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>>@&lt;@\'@\"@\\@#@(@)</param-value>
		</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;
	}
}