java类过滤器，防止页面SQL注入

package com.tarena.dingdang.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;  
  
public class AntiSqlInjectionfilter implements Filter {  
  
    public void destroy() {  
        // TODO Auto-generated method stub  
    }  
      
    public void init(FilterConfig arg0) throws ServletException {  
        // TODO Auto-generated method stub  
    }  
      
    public void doFilter(ServletRequest args0, ServletResponse args1,  
            FilterChain chain) throws IOException, ServletException {  
        HttpServletRequest req=(HttpServletRequest)args0;  
        HttpServletRequest res=(HttpServletRequest)args1;  
         //获得所有请求参数名  
        Enumeration params = req.getParameterNames();  
        String sql = "";  
        while (params.hasMoreElements()) {  
            //得到参数名  
            String name = params.nextElement().toString();  
            //System.out.println("name===========================" + name + "--");  
            //得到参数对应值  
            String[] value = req.getParameterValues(name);  
            for (int i = 0; i < value.length; i++) {  
                sql = sql + value[i];  
            }  
        }  
        //System.out.println("============================SQL"+sql);  
        //有sql关键字，跳转到error.html  
        if (sqlValidate(sql)) {  
            throw new IOException("您发送请求中的参数中含有非法字符");  
            //String ip = req.getRemoteAddr();  
        } else {  
            chain.doFilter(args0,args1);  
        }  
    }  
      
    //效验  
    protected static boolean sqlValidate(String str) {  
        str = str.toLowerCase();//统一转为小写  
        String badStr = "'|and|exec|execute|insert|select|delete|update|count|drop|*|%|chr|mid|master|truncate|" +  
                "char|declare|sitename|net user|xp_cmdshell|;|or|-|+|,|like'|and|exec|execute|insert|create|drop|" +  
                "table|from|grant|use|group_concat|column_name|" +  
                "information_schema.columns|table_schema|union|where|select|delete|update|order|by|count|*|" +  
                "chr|mid|master|truncate|char|declare|or|;|-|--|+|,|like|//|/|%|#";//过滤掉的sql关键字，可以手动添加  
        String[] badStrs = badStr.split("\|");  
        for (int i = 0; i < badStrs.length; i++) {  
            if (str.indexOf(badStrs[i]) >= 0) {  
                return true;  
            }  
        }  
        return false;  
    }  
}  
  
  
<!--在web.xml文件中的配置-->  
<!-- 防止SQL注入的过滤器 -->  
    <filter>  
        <filter-name>antiSqlInjection</filter-name>  
        <filter-class>com.tarena.dingdang.filter.AntiSqlInjectionfilter</filter-class>  
    </filter>  
    <filter-mapping>  
        <filter-name>antiSqlInjection</filter-name>  
        <url-pattern>/*</url-pattern>  
    </filter-mapping>