【求指教】jQuery发送Ajax请求Servlet端乱码问题

我用jquery发送ajax请求到servlet端，用IE 浏览器，servlet接受到的中文参数为乱码，火狐和谷歌浏览器中文显示正常
页面编码均为UTF-8；
<%@page contentType="text/html" pageEncoding="UTF-8"%>$(function(){
                    var word = document.getElementById("searchinput").value;
                    //alert(word);
                    $.ajax({
                        async:false,
                        dataType:'json',
                        type:"get",
                        url:"search.do?op=" + op + "&keyword=" + word,
                        success:function(json){
                        ……                      
                    });
                });servlet端代码为
        response.setContentType("text/html;charset=UTF-8");
        String keyword = request.getParameter("keyword");
        //keyword = new String(keyword.getBytes("ISO-8859-1"), "GBK");
        System.out.println("keyword-->" + keyword);
        试过keyword = new String(keyword.getBytes("ISO-8859-1"), "GBK"); 输出的keyword=?????,还是乱码 也添加了Filter，代码如下
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.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class CharsetFilter implements Filter {
private String charset = "UTF-8";    @Override
public void destroy() { }    @Override
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
if (request.getMethod().equalsIgnoreCase("post"))
request.setCharacterEncoding(charset);
else {
//System.out.println(charset);
EncodingRequest erq = new EncodingRequest(request, charset);
req = erq;
}
chain.doFilter(req, resp);
} public void init(FilterConfig config) throws ServletException {
String charset = config.getInitParameter("CHARSET");
if (charset != null && charset.equals(""))
this.charset = charset;
}
}