Struts2学习4——防sql注入过滤器

web.xml

<!-- sql Filter -->
     <filter>
        <filter-name>SqlFilter</filter-name>
        <filter-class>Utils.SqlFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>SqlFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

Utils.SqlFilter

package Utils;

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;

//过滤sql关键字的Filter
public class SqlFilter implements Filter {

    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {

        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        // 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("被匹配字符串：" + sql);
        if (sqlValidate(sql)) {
            res.sendRedirect("/error.jsp");
        } else {
            chain.doFilter(req, res);
        }
    }

    // 校验
    protected static boolean sqlValidate(String str) {
        str = str.toLowerCase();// 统一转为小写
        // String badStr = "and|exec";
        String badStr = "'|and|exec|execute|insert|select|delete|update|count|drop|chr|mid|master|truncate|char|declare|sitename|net user|xp_cmdshell|or|like";
        /*
         * String badStr =
         * "'|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]) != -1) {
                System.out.println("匹配到：" + badStrs[i]);
                return true;
            }
        }
        return false;
    }

    public void init(FilterConfig filterConfig) throws ServletException {
        // throw new UnsupportedOperationException("Not supported yet.");
    }

    public void destroy() {
        // throw new UnsupportedOperationException("Not supported yet.");
    }
}

另外程序代码中避免字符串拼接，使用PreparedStatement。