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>