Java防止SQL流入的几个途径

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01	import java.io.IOException;02	import java.util.Iterator;03	import javax.servlet.Filter;04	import javax.servlet.FilterChain;05	import javax.servlet.FilterConfig;06	import javax.servlet.ServletException;07	import javax.servlet.ServletRequest;08	import javax.servlet.ServletResponse;09	import javax.servlet.http.HttpServletRequest;10	import javax.servlet.http.HttpServletResponse;11	/**12	* 通过Filter过滤器来防SQL注入攻击13	*14	*/15	public class SQLFilter implements Filter {16	private String inj_str = "'|and|exec|insert|select|delete|update|count|*|%|chr|mid|master|truncate|char|declare|; |or|-|+|,";17	protected FilterConfig filterConfig = null;18	/**19	* Should a character encoding specified by the client be ignored?20	*/21	protected boolean ignore = true;22	public void init(FilterConfig config) throws ServletException {23	this.filterConfig = config;24	this.inj_str = filterConfig.getInitParameter("keywords");25	}26	public void doFilter(ServletRequest request, ServletResponse response,27	FilterChain chain) throws IOException, ServletException {28	HttpServletRequest req = (HttpServletRequest)request;29	HttpServletResponse res = (HttpServletResponse)response;30	Iterator values = req.getParameterMap().values().iterator();//获取所有的表单参数31	while(values.hasNext()){32	String[] value = (String[])values.next();33	for(int i = 0;i < value.length;i++){34	if(sql_inj(value[i])){35	//TODO这里发现sql注入代码的业务逻辑代码36	return;37	}38	}39	}40	chain.doFilter(request, response);41	}42	public boolean sql_inj(String str)43	{44	String[] inj_stra=inj_str.split("\\|");45	for (int i=0 ; i < inj_stra.length ; i++ )46	{47	if (str.indexOf(" "+inj_stra[i]+" ")>=0)48	{49	return true;50	}51	}52	return false;53	}54	}也可以单独在需要防范SQL注入的JavaBean的字段上过滤：1	/**2	* 防止sql注入3	*4	* @param sql5	* @return6	*/7	public static String TransactSQLInjection(String sql) {8	return sql.replaceAll(".*([';]+|(--)+).*", " ");9	}