Avoid URL has invalid chars

CharFilter.java

package com.jst.sys.filter;

import java.io.IOException;
import java.util.Enumeration;

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;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;

/**
 * 非法字符过滤器
 * 1.所有非法字符配置在web.xml中，如需添加新字符，请自行配置
 * 2.请注意请求与相应时的编码格式设置，否则遇到中文时，会出现乱码(GBK与其子集应该没问题)
 * @author lee
 *
 */
public class CharFilter implements Filter {
	private Logger log = Logger.getLogger(CharFilter.class);
	private String encoding;
	private String[] legalNames;
	private String[] illegalChars;
	
	public void init(FilterConfig filterConfig) throws ServletException {
		encoding = filterConfig.getInitParameter("encoding");
		legalNames = filterConfig.getInitParameter("legalNames").split(",");
		illegalChars = filterConfig.getInitParameter("illegalChars").split(",");
	}
	
	public void destroy() {
		encoding = null;
		legalNames = null;
		illegalChars = null;
	}
	

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain filterChain) throws IOException, ServletException {
		
		HttpServletRequest req = (HttpServletRequest)request;
		HttpServletResponse res = (HttpServletResponse) response;
		
		//必须手动指定编码格式
		req.setCharacterEncoding(encoding);
		String tempURL = req.getRequestURI(); 
		log.info(tempURL);
		Enumeration params = req.getParameterNames();
		
		//是否执行过滤  true：执行过滤  false：不执行过滤
		boolean executable = true;
		
		//非法状态  true：非法  false；不非法
		boolean illegalStatus = false;
		String illegalChar = "";
		//对参数名与参数进行判断
		w:while(params.hasMoreElements()){
			
			String paramName = (String) params.nextElement();
			
			executable = true;
			
			//密码不过滤
			if(paramName.toLowerCase().contains("password")){
				executable = false;
			}else{
				//检查提交参数的名字，是否合法，即不过滤其提交的值
				f:for(int i=0;i<legalNames.length;i++){
					if(legalNames[i].equals(paramName)){
						executable = false;
						break f;
					}
				}
			}
			
			if(executable){
				String[] paramValues = req.getParameterValues(paramName);
				
				f1:for(int i=0;i<paramValues.length;i++){
					
					String paramValue = paramValues[i];
					
					f2:for(int j=0;j<illegalChars.length;j++){
						
						illegalChar = illegalChars[j];
						
						if(paramValue.indexOf(illegalChar) != -1){
							illegalStatus = true;//非法状态
							break f2;
						}
					}
					
					if(illegalStatus){
						break f1;
					}
					
				}
			}
			
			if(illegalStatus){
				break w;
			}
		}
		//对URL进行判断
		for(int j=0;j<illegalChars.length;j++){
			
			illegalChar = illegalChars[j];
			
			if(tempURL.indexOf(illegalChar) != -1){
				illegalStatus = true;//非法状态
				break;
			}
		}
		if(illegalStatus){
			//必须手动指定编码格式
			res.setContentType("text/html;charset="+encoding);
			res.setCharacterEncoding(encoding);
			res.getWriter().print("<script>window.alert('当前链接中存在非法字符');window.history.go(-1);</script>");
		}else{
			filterChain.doFilter(request, response);
		}
	}

}

filter comfig.xml

<filter>
        <filter-name>charFilter</filter-name>
        <filter-class>com.jst.sys.filter.CharFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>legalNames</param-name>
            <param-value>content1,ver</param-value>
        </init-param>
        <init-param>
            <param-name>illegalChars</param-name>
            <param-value>|,$,@,',&quot;,\',\&quot;,&lt;,>,(,),+,CR,LF,\&quot;,&quot;,\</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>charFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>