package com.pdsu.filter;import java.io.IOException;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.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;/*** 类说明：HTML特殊字符过滤器* * @author 作者: LiuJunGuang* @version 创建时间：2011-11-18 下午07:36:44*/
public class HTMLCharacterFilter implements Filter {public void init(FilterConfig filterConfig) throws ServletException {}public void doFilter(ServletRequest req, ServletResponse resp,FilterChain chain) throws IOException, ServletException {HttpServletRequest request = (HttpServletRequest) req;HttpServletResponse response = (HttpServletResponse) resp;chain.doFilter(new HTMLCharacterRequest(request), response);}public void destroy() {}
}// html特殊字符处理类
class HTMLCharacterRequest extends HttpServletRequestWrapper {public HTMLCharacterRequest(HttpServletRequest request) {super(request);}@Overridepublic String getParameter(String name) {return filter(super.getParameter(name));}@Overridepublic String[] getParameterValues(String name) {String[] values = super.getParameterValues(name);if (values == null || values.length == 0)return values;for (int i = 0; i < values.length; i++) {String str = values[i];values[i] = filter(str);}return values;}/*** 对特殊的html字符进行编码* * @param message* @return*/private String filter(String message) {if (message == null)return (null);char content[] = new char[message.length()];message.getChars(0, message.length(), content, 0);StringBuilder result = new StringBuilder(content.length + 50);for (int i = 0; i < content.length; i++) {switch (content[i]) {case '<':result.append("&lt;");break;case '>':result.append("&gt;");break;case '&':result.append("&amp;");break;case '"':result.append("&quot;");break;default:result.append(content[i]);}}return (result.toString());}
}

在web.xml中添加如下内容：

<!-- HTML特殊字符过滤器 --><filter><filter-name>HTMLFiter</filter-name><filter-class>com.pdsu.filter.HTMLCharacterFilter</filter-class></filter><filter-mapping><filter-name>HTMLFiter</filter-name><url-pattern>/*</url-pattern></filter-mapping>