简单web工程创建步骤和jsp语法大全（配合代码）(8)

request.setAttribute(\您还没有登录！\

request.getRequestDispatcher(loginPage).forward(request, response); }

//放行请求 else{

chain.doFilter(request, response); } } }

web.xml文件配置Filter

authority

filter.AuthorityFilter

encoding UTF-8

loginPage /index.jsp

proLigin /proLogin.jsp

authority

/*

应用举例——日志拦截器 创建Filter处理类 package filter;

import java.io.IOException;

import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest;

public class LogFilter implements Filter{ //FilterConfig可用于访问Filter的配置信息 private FilterConfig config;

@Override //实现初始化方法

public void init(FilterConfig config){ this.config = config; }

@Override //实现销毁方法

public void destroy(){ this.config = null; }

@Override

//执行过滤的核心方法

public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain)

throws IOException,ServletException{

//-----------下面对用户请求进行预处理-------------- //获取ServletContext对象，用于记录日志

ServletContext context = this.config.getServletContext(); //将请求转换成HttpServletRequest请求

HttpServletRequest hRequest = (HttpServletRequest)request; //记录日志

context.log(\已经截获到用户的请求地址：\

//Filter只是链式处理，请求依然放行到目的地址 chain.doFilter(request, response);

//-----------下面对服务器响应执行后处理-------------- context.log(\过滤结束\

context.log(\请求被定位到\

} }

web.xml文件配置Filter

log

filter.LogFilter

log

/* 5.3.13 Listener

作用类似于load-on-startup Servlet，用于在web启动时启动某些后台