Java 使用过滤器过滤非法字符

package com.iapppay.wap.common;

import java.io.IOException;
import java.io.PrintWriter;

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.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.iapppay.wap.control.LoginControl;

/**
 * Servlet Filter implementation class CharFilter
 */
@WebFilter("/CharFilter")
public class CharFilter implements Filter {

    private String[] characterParams = null;
    private boolean OK = true;
     private static Logger logger = LoggerFactory.getLogger(LoginControl.class);
    /**
     * Default constructor.
     */
    public CharFilter() {
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Filter#destroy()
     */
    public void destroy() {
        // TODO Auto-generated method stub
    }

    /**
     * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
     */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest servletrequest = (HttpServletRequest) request;
        HttpServletResponse servletresponse = (HttpServletResponse) response;
        boolean status = false;
        java.util.Enumeration params = request.getParameterNames();
        String param = "";
        String paramValue = "";
        servletresponse.setContentType("text/html");
        servletresponse.setCharacterEncoding("utf-8");
        while (params.hasMoreElements()) {
            param = (String) params.nextElement();
            String[] values = request.getParameterValues(param);
            paramValue = "";
            if (OK) {// 过滤字符串为0个时 不对字符过滤
                for (int i = 0; i < values.length; i++)
                    paramValue = paramValue + values[i];
                for (int i = 0; i < characterParams.length; i++)
                    if (paramValue.indexOf(characterParams[i]) >= 0) {
                        status = true;
                        break;
                    }
                if (status)
                    break;
            }
        }
        // System.out.println(param+"="+paramValue+";");
        
        if (status) {
            logger.warn("输入的值不合法："+paramValue);
            StringBuffer url = servletrequest.getRequestURL();
            servletresponse.sendRedirect(servletrequest.getContextPath()+"/v/login/illegalchar?url="+url.toString());
        } else
            chain.doFilter(request, response);

    }

    /**
     * @see Filter#init(FilterConfig)
     */
    public void init(FilterConfig fConfig) throws ServletException {
        String str=fConfig.getInitParameter("characterParams");
        if(str==null||"".equals(str)){
            OK = false;
        }else{
            this.characterParams = fConfig.getInitParameter("characterParams").split(",");
        }

    }

}

WEB.XML

<filter>
          <filter-name>charFilter</filter-name>
          <filter-class>com.iapppay.wap.common.CharFilter</filter-class>
          <init-param>
              <param-name>characterParams</param-name>
              <param-value>|,&amp;,;,$,%,',&quot;,\',\&quot;,\,&lt;,&gt;,(,),+,CR,LF,BS</param-value>
          </init-param>
  </filter>
  <filter-mapping>
      <filter-name>charFilter</filter-name>
      <url-pattern>/v/*</url-pattern>
  </filter-mapping>