Servlet 过滤器两种配置方法

方法一（注解）

/**
* 使用注解标注过滤器
* @webfilter将一个实现了javax.servlet.filte接口的类定义为过滤器
* 属性filtername声明过滤器的名称,可选
* 属性urlpatterns指定要过滤 的url模式,也可使用属性value来声明.(指定要过滤的url模式是必选属性)
*/
@webfilter(filtername="testfilter",urlpatterns="*.action")

方法二（配置web.xml文件）

<filter>
    <filter-name>loginfilter</filter-name>
    <filter-class>cn.edu.njit.filter.loginfilter</filter-class>
    <init-param>
        <param-name>loginui</param-name>
        <param-value>/home/loginui</param-value>
    </init-param>
    <init-param>
        <param-name>loginprocess</param-name>
        <param-value>home/login</param-value>
    </init-param>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>utf-8</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>loginfilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

例：servlet3.0 以上注解式配置方法

package com.tunny.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.annotation.webfilter;

// servlet3.0 以上注解式配置方法
@webfilter(filtername="encodingfilter",urlpatterns="*.action")
public class encodingfilter implements filter{

    public void destroy() {
        
    }

    // 主要的业务逻辑都写在此方法中
    public void dofilter(servletrequest req, servletresponse resp,
            filterchain chain) throws ioexception, servletexception {
        req.setcharacterencoding("utf-8");
        resp.setcharacterencoding("utf-8");
        resp.setcontenttype("text/html;charset=utf-8");
        system.out.println("过滤器帮你转换码完毕");
        chain.dofilter(req, resp);  // 放行或者向后继续执行 
    }

    public void init(filterconfig config) throws servletexception {
        
    }

}

listener监听器

// session="false"  关闭session
<%@ page language="java" import="java.util.*" pageencoding="utf-8" session="false" %>