SpringMVC过滤器

今天用到了过滤器小结一下：
SpringMVC过滤器在web.xml中通常有两种配置一种是字符集过滤器（CharacterEncodingFilter），一种是自定义的过滤器（实现Filter接口）
过滤器类继承关系和实现如下：

web.xml字符集过滤器配置如下

<filter>      <filter-name>characterEncodingFilter</filter-name>      <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>      <init-param>          <param-name>encoding</param-name>          <param-value>UTF-8</param-value>      </init-param>      <init-param>          <param-name>forceEncoding</param-name>          <param-value>true</param-value>      </init-param>  </filter>  <filter-mapping>      <filter-name>characterEncodingFilter</filter-name>      <url-pattern>/*</url-pattern>  </filter-mapping> 

CharacterEncodingFilter源码如下：

package org.springframework.web.filter;import java.io.IOException;import javax.servlet.FilterChain;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.web.filter.OncePerRequestFilter;public class CharacterEncodingFilter extends OncePerRequestFilter {    private String encoding;    private boolean forceEncoding = false;    public CharacterEncodingFilter() {    }    public void setEncoding(String encoding) {        this.encoding = encoding;    }    public void setForceEncoding(boolean forceEncoding) {        this.forceEncoding = forceEncoding;    }    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {        if(this.encoding != null && (this.forceEncoding || request.getCharacterEncoding() == null)) {            request.setCharacterEncoding(this.encoding);            if(this.forceEncoding) {                response.setCharacterEncoding(this.encoding);            }        }        filterChain.doFilter(request, response);    }}

encoding属性：指定的编码格式（在该配置文件中该属性被SpringIoC注入的值为UTF-8）
forceEncoding属性：表示在response字符集是否也采用encoding属性值（源码中默认为false,所以想要项目编码格式一致，应该在web.xml中配置其初始值为true）
当属性注入完成后开始执行doFilterInternal（）函数：在this.encoding中指定了值的前提下如果指定forceEncoding=true或者发出的请求中没有指定request字符集的编码格式（request.getCharacterEncoding() == null)）那么将过滤到的request的字符集设置为encoding指定的值，并根据this.forceEncoding的值判断是否需要设置response的字符集的值，如果this.encoding为空那么直接放行.

web.xml自定义过滤器配置如下

  <filter>    <filter-name>LoginFilter</filter-name>    <filter-class>com.filter.LoginFilter</filter-class>    <init-param>      <param-name>unchecked</param-name>      <param-value>/WEB-INF/Public/login.jsp,/R33/menu/login1.do,/R33/menu/login.do,/R33/Js/jquery.sorted.js,/R33/Js/jquery.sorted.js,/R33/menu/childs1.do</param-value>    </init-param>  </filter>

注：在为param-value字段指定值时最好可一行写，换行后貌似会出现空格问题

LoginFilter代码如下

import javax.servlet.*;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import java.io.IOException;import java.util.Arrays;public class LoginFilter implements Filter{    private String[] unchecked;    //private List<User> userarr=new ArrayList<User>();    public void init(FilterConfig config) throws ServletException {        String url=config.getInitParameter("unchecked");        unchecked=url.split(",");        System.out.println(url+"==============");    }    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {        System.out.println("登陆路径===="+java.util.Arrays.toString(unchecked));        //如何获取当前的路径        HttpServletRequest request1=(HttpServletRequest)request;        HttpServletResponse response1=(HttpServletResponse)response;        HttpSession session=request1.getSession();        User user=(User) session.getAttribute("u");        String currenturl=request1.getRequestURI();        System.out.println("当前的路径====="+currenturl);        //路径放行*/        if(Arrays.asList(unchecked).contains(currenturl)||user!=null){            chain.doFilter(request,response);        }else{            response1.sendRedirect(request1.getContextPath()+"/menu/login1.do");        }    }    public void destroy() {    }}

设置项目开始运行时的跳转页（登陆页面）

  <welcome-file-list>    <welcome-file>/R33/menu/login1.do</welcome-file>  </welcome-file-list>

login1.do代码

    @RequestMapping("/login1")    public String login1(){        return "Public/login";    }

因为/R33/menu/login1.do在unchecked集合中所以直接放行，登陆页面跳转出来。

输入用户名和密码点击登录，登录按钮的action为/R33/menu/login.do，该地址也在unchecked集合中直接放行，login.do代码如下

    @RequestMapping("/login")    public String login(User user,HttpServletRequest request,HttpServletResponse responseUser,Model model){        System.out.println(user.getName()+"----"+user.getPassword());        System.out.println("=======");        User u=uservice.querybyUser(user);//查询数据库中是否有此用户        request.getSession().setAttribute("u",u);        System.out.println("=======");        if(u==null){            return "redirect:/menu/login1.do";        }else{            //获取用户一级菜单列表            List<Menu> list=aservice.querybyRoleid(u.getRole_id());            model.addAttribute("mlist",list);            model.addAttribute("u",u);            return "../index";        }    }

LoginFilter的doFilter（）函数功能是如果请求的路径在 unchecked集合中，或者用户已登录成功（user！=null）那么所有请求均放行，其他请求一律跳转到登录页面。