spring mvc出现乱码，在web.xml中加filter不起作用，如何解决？

一下是web.xml的内容
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <display-name>ss</display-name>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <filter>
        <filter-name>EncodingFilter</filter-name>
        <filter-class>org.ss.common.EncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>EncodingFilter</filter-name>
        <url-pattern>*.do</url-pattern>
    </filter-mapping>
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>redirect.jsp</welcome-file>
    </welcome-file-list>
</web-app>请问诸位大侠，原因何在？

解决方案 »

  1.   

    <%@page contentType="text/html" pageEncoding="UTF-8"%>
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
       "http://www.w3.org/TR/html4/loose.dtd"><html>
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        </head>这些是已经设置好了的，不是这里的问题
      

  2.   

    刚发现过滤器是起作用的，从.getCharacterEncoding()中得到的是正确的编码，难道说字符在进入过滤器之前就已经乱码了？
    想不明白啊
      

  3.   

    在过滤器里设置encoding之前，我调用request.getCharacterEncoding()得到的是null可是我已经在jsp页面里边设置了
    <%@page contentType="text/html" pageEncoding="UTF-8"%> 
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
      "http://www.w3.org/TR/html4/loose.dtd"> <html> 
        <head> 
            <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 
        </head>
    取到的encoding为什么是null呢？