servlet乱码问题~~~

servlet出现乱码改了也不行！！
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        response.setContentType("text/html;charset=GB2312");
        request.setCharacterEncoding("gb2312");
        PrintWriter out = response.getWriter();
加上这两行也不行啊，为什么呢？？
怎么改呀
----------------解决方案--------------------------------------------------------
直接new String (request.getParameter("要获取的对象").getBytes("ISO-8859-1"),"gbk");   
再不就写过滤器
其实就两行核心代码
public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain arg2) throws IOException, ServletException {
         request.setCharacterEncoding("gbk");
         response.setCharacterEncoding("gbk");
         arg2.doFilter(request,response);

    }
记住过滤器要继承Filter
----------------解决方案--------------------------------------------------------
打快了,打错了，是要implements Filter 实现这个接口
----------------解决方案--------------------------------------------------------