如何防止web项目中的sql注入

通过一个Filter来防止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;
}
}



复制上边的代码可以直接生产包和Java对象
<!--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>