JAVA Web中过滤器

package com.svse.filter; 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.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class DemoFilter implements Filter { private String str = null; public void init(FilterConfig config) throws ServletException { this.str = config.getInitParameter("xmlname"); // xmlname来自配制文件中的init-param节点中的。。。。 } public void doFilter(ServletRequest req, ServletResponse res, FilterChain dochina) throws IOException, ServletException { // 第一步，强制转换 HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; request.setCharacterEncoding("gbk");// // response.setContentType("text/html;charset=gbk"); //在使用过滤器时，如果要处理字符编码的问题，那么一定要求 //提交的页面中的提交方式是post String name = request.getParameter("textname"); System.out.println("name=" + name); String[] s = str.split(","); boolean f = false; for (int i = 0; i < s.length; i++) { if (name.equals(s[i])) { f = true; } }// end for if (f) { request.getRequestDispatcher("error.jsp").forward(req, res); } else { // request.getRequestDispatcher("show.jsp").forward(req, res); dochina.doFilter(req, res); } } // 要建一个过滤器，一定要实现Filter接口，但不一定要继承HttpServlet public void destroy() { // TODO Auto-generated method stub } }