代码如下：
package com.liufeng.sys.filter;涛涛电脑知识网
涛涛电脑知识网
import java.io.IOException;
import java.io.PrintWriter;
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;
public class IllegalCharacterFilter implements Filter {
private String[] characterParams = null;
private boolean OK=true;
public void destroy() {
// TODO Auto-generated method stub
}
/**
* 此程序块主要用来解决参数带非法字符等过滤功能
*/
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain arg2) throws IOException, ServletException {
HttpServletRequest servletrequest = (HttpServletRequest) request;
HttpServletResponse servletresponse = (HttpServletResponse) response;
boolean status = false;
java.util.Enumeration params = request.getParameterNames();
String param="";
String paramValue = "";
servletresponse.setContentType("text/html");
servletresponse.setCharacterEncoding("utf-8");
while (params.hasMoreElements()) {
param = (String) params.nextElement();
String[] values = request.getParameterValues(param);
paramValue = "";
if(OK){//过滤字符串为0个时 不对字符过滤
for (int i = 0; i < values.length; i++)
paramValue=paramValue+values[i];
for(int i=0;i<characterParams.length;i++)
if (paramValue.indexOf(characterParams[i]) >= 0) {
status = true;
break;
}
if(status)break;
}
}
// System.out.println(param+"="+paramValue+";");
if (status) {
PrintWriter out = servletresponse.getWriter();
out
.print("<script language='javascript'>alert(\"对不起！您输入内容含有非法字符。如：\\\"'\\\".等\");"
// + servletrequest.getRequestURL()
+ "window.history.go(-1);</script>");
}else
arg2.doFilter(request, response);
}
public void init(FilterConfig config) throws ServletException {
if(config.getInitParameter("characterParams").length()<1)
OK=false;
else
this.characterParams = config.getInitParameter("characterParams").split(",");
}
}
二。在web.xml文件中加入如下内容：
<!-- 非法字符过滤器 -->
<filter>
<filter-name>IllegalCharacterFilter</filter-name>
<filter-class>
com.liufeng.sys.filter.IllegalCharacterFilter
</filter-class>
<init-param>
<param-name>characterParams</param-name>
<param-value>',@</param-value><!-- 此处加入要过滤的字符或字符串，以逗号隔开 -->
</init-param>
</filter>
<filter-mapping>
<filter-name>IllegalCharacterFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
重启你的服务器就OK了。
这样，增加此过滤器后能提高网站的安全，防止SQL注入，防止跨站脚本XSS等。
