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" %>