Java防止SQL注入的几个途径

Java防SQL注入，最简单的办法是杜绝SQL拼接，SQL注入攻击能得逞是因为在原有SQL语句中加入了新的逻辑，如果使用PreparedStatement来代替Statement来执行SQL语句，其后只是输入参数，SQL注入攻击手段将无效，这是因为PreparedStatement不允许在不同的插入时间改变查询的逻辑结构，大部分的SQL注入已经挡住了，在WEB层我们可以过滤用户的输入来防止SQL注入比如用Filter来过滤全局的表单参数。

import java.io.IOException;import java.util.Iterator;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;/*** 通过Filter过滤器来防SQL注入攻击**/public class SQLFilter implements Filter {private String inj_str = "'|and|exec|insert|select|delete|update|count|*|%|chr|mid|master|truncate|char|declare|; |or|-|+|,";protected FilterConfig filterConfig = null;/*** Should a character encoding specified by the client be ignored?*/protected boolean ignore = true;public void init(FilterConfig config) throws ServletException {this.filterConfig = config;this.inj_str = filterConfig.getInitParameter("keywords");}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {HttpServletRequest req = (HttpServletRequest)request;HttpServletResponse res = (HttpServletResponse)response;Iterator values = req.getParameterMap().values().iterator();//获取所有的表单参数while(values.hasNext()){String[] value = (String[])values.next();for(int i = 0;i < value.length;i++){if(sql_inj(value[i])){//TODO这里发现sql注入代码的业务逻辑代码return;}}}chain.doFilter(request, response);}public boolean sql_inj(String str){String[] inj_stra=inj_str.split("\\|");for (int i=0 ; i < inj_stra.length ; i++ ){if (str.indexOf(" "+inj_stra[i]+" ")>=0){return true;}}return false;}}

也可以单独在需要防范SQL注入的JavaBean的字段上过滤：

/*** 防止sql注入** @param sql* @return*/public static String TransactSQLInjection(String sql) {return sql.replaceAll(".*([';]+|(--)+).*", " ");}