2个有用的过滤器示例

【2个有用的过滤器示例】给出了一些有用的过滤器示例。
仅通过过滤器发送响应的示例
MyFilter.java

import java.io.*; import javax.servlet.*; public class MyFilter implements Filter{ public void init(FilterConfig arg0) throws ServletException {} public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { PrintWriter out=res.getWriter(); out.print("< br/> this site is underconstruction.."); out.close(); } public void destroy() {} }

单页访问者计数示例
MyFilter.java

import java.io.*; import javax.servlet.*; public class MyFilter implements Filter{ static int count=0; public void init(FilterConfig arg0) throws ServletException {} public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { PrintWriter out=res.getWriter(); chain.doFilter(request, response); out.print("< br/> Total visitors "+(++count)); out.close(); } public void destroy() {} }

在过滤器中检查总响应时间的示例
MyFilter.java

import java.io.*; import javax.servlet.*; public class MyFilter implements Filter{ static int count=0; public void init(FilterConfig arg0) throws ServletException {} public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { PrintWriter out=res.getWriter(); long before=System.currentTimeMillis(); chain.doFilter(request, response); long after=System.currentTimeMillis(); out.print("< br/> Total response time "+(after-before)+" miliseconds"); out.close(); } public void destroy() {} }