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(".*([';]+|(--)+).*", " "); } |