Ehcache 使用SimplePageCachingFilter进行页面缓存，中文出现乱码?

Ehcache 使用SimplePageCachingFilter进行页面缓存，中文出现乱码，未用之前是正常的。我增加了过滤器也不好用，见code：

/**
     * The default character encoding to set for requests that pass through this
     * filter.
     * 字符集编码设置
     */
    protected String encoding = null;

    /* (non-Javadoc)
     * @see net.sf.ehcache.constructs.web.filter.CachingFilter#doFilter(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain)
     */
    @Override
    public void doFilter(HttpServletRequest request,
            HttpServletResponse response, FilterChain chain)
            throws AlreadyGzippedException, AlreadyCommittedException,
            FilterNonReentrantException, LockTimeoutException, Exception {
        if (encoding != null)
        {
            request.setCharacterEncoding(encoding);
        }
        super.doFilter(request, response, chain);
    }
    

    /* (non-Javadoc)
     * @see net.sf.ehcache.constructs.web.filter.CachingFilter#doInit(javax.servlet.FilterConfig)
     */
    @Override
    public void doInit(FilterConfig filterConfig) throws CacheException {
        this.encoding = filterConfig.getInitParameter("encoding");
        super.doInit(filterConfig);
    }

使用环境：ubuntu14.04 ,weblogic 9.24,java 1.5,eclipse